Material Selection

Engineering Encyclopedia Saudi Aramco DeskTop Standards

MATERIAL SELECTION

Note: The source of the technical material in this volume is the Professional Engineering Development Program (PEDP) of Engineering Services. Warning: The material contained in this document was developed for Saudi Aramco and is intended for the exclusive use of Saudi Aramco’s employees. Any material contained in this document which is not already in the public domain may not be copied, reproduced, sold, given, or disclosed to third parties, or otherwise used in whole, or in part, without the written permission of the Vice President, Engineering Services, Saudi Aramco.

Chapter : Mechanical File Reference: MEX-101.02

For additional information on this subject, contact PEDD Coordinator on 874-6556

Engineering Encyclopedia

Piping, Pipelines & Valves Material Selection

Section

Page(s)

INFORMATION................................................................................................................5 INTRODUCTION .............................................................................................................5 FACTORS THAT AFFECT MATERIAL SELECTION ......................................................6 PHYSICAL PROPERTIES ...............................................................................................8 Yield and Tensile Strength ....................................................................................8 Creep Strength....................................................................................................11 Material Toughness.............................................................................................13 Charpy V Notch Testing ......................................................................................14 Effect of Temperature on Toughness..................................................................16 Effect of Carbon on Toughness...........................................................................18 Effect of Heat Treatment and Grain Size ............................................................19 Effect of Chemical Composition or Alloying Elements.........................................19 Fatigue Strength .......................................................................................................20 Effects of Hardness ..................................................................................................21 Fabrication................................................................................................................21 CORROSION RESISTANCE .........................................................................................23 Suitability for Wet, Sour Service ...............................................................................26 Hydrogen Blistering.............................................................................................27 Hydrogen-Induced Cracking (Stepwise Cracking)...............................................29 Sulfide Stress Cracking .......................................................................................31 Stress Corrosion Cracking ..................................................................................32 AVAILABILITY AND COST............................................................................................34 PRIMARY PIPE MANUFACTURING PROCESSES......................................................35 Seamless Pipe..........................................................................................................36 Electric Resistance-Welded Pipe..............................................................................39 Submerged Arc-Welded Pipe ...................................................................................43 Spiral-Welded Pipe...................................................................................................44 Furnace-Welded Pipe...............................................................................................44 Joint Quality Factor...................................................................................................44 SAUDI ARAMCO LIMITATIONS ON METALLIC PIPE..................................................45 SAES and SAMSS General Limitation ................................................................45 Pipe Grade Specified Minimum (SMYS) .............................................................46 Pipe Size .............................................................................................................46 Manufacturing Process of Line Pipe....................................................................47 Low Temperature Limitation on Line Pipe & Components ..................................47 MATERIAL SELECTION PROCESS .............................................................................49

Saudi Aramco DeskTop Standards

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Basic Material for Pipe Systems, SAES-L-032....................................................50 Nelson Chart for Hydrogen Service.....................................................................50 Sample Problem1: SAES-L-032 - Crude Pipeline....................................................53 Sample Problem 2: Steam Line ...............................................................................54 Sample Problem 3: Nelson Chart ............................................................................55 Basic Material for Valves, SAES-L-008 ............................................................56 Sample Problem 4: Valve Selection.........................................................................57 Determining Applicable SAES and SAMSS for Pipe and Piping Components ....58 Industry Standards for Pipe and Piping Components..........................................58 Material Designation by Industry Standard .........................................................59 Material Selection for Low-Temperature Service ................................................61 Material Designation for Components .................................................................62 Material Selection for Lined, Coated, and Nonmetallic Piping.............................62 SAES-L-005 Piping Specification ........................................................................63 SUMMARY ....................................................................................................................65 ADDENDUM ..................................................................................................................66 ADDENDUM A: APPLICABLE SAUDI ARAMCO MATERIAL SPECIFICATIONS FOR PIPE AND PIPING COMPONENTS .......................................69 ADDENDUM B...............................................................................................................74 INDUSTRY STANDARDS APPLICABLE FOR PIPE AND PIPING COMPONENTS.....74 ADDENDUM C...............................................................................................................82


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LIST OF FIGURES Figure 1. Typical Stress-Strain Diagram for Steel ...........................................................9 Figure 2. Yield Strength (0.2% Offset Proof).................................................................10 Figure 3. Typical Curve Showing Three Stages of Creep .............................................12 Figure 4. Typical Rupture Strength of Incoloy Alloy 800HT, Also Effect of Temperature on Tensile and Yield Strength is Clear....................................................................13 Figure 5. Line pipe rupture, crack propagated at the speed of sound ..........................15 Figure 6. Charpy V Notch Testing Machine ..................................................................16 Figure 7. Absorbed Energy Versus Temperature..........................................................17 Figure 8. Effects of Carbon Content on the Transition Curves for Steel ......................18 Figure 9. Design Fatigue Curve .....................................................................................20 Figure 10. Hydrogen Atom Diffusion Through the Steel Wall........................................27 Figure 11. Typical Hydrogen Blistering and HIC in the Wall of a Tank........................28 Figure 12. Stepwise Cracking of a Low-Strength Pipeline Steel Exposed to H2S .......30 Figure 13. Stepwise Cracking of a Low-Strength Pipeline Steel Exposed to H2S .......30 Figure 14. Mechanism of Sulfide Stress Cracking ........................................................32 Figure 15. External Stress Corrosion Cracking in a Line Pipe ......................................33 Figure 16A. Typical Seamless Pipe Manufacturing Process........................................37 Figure 16B. Typical Seamless Pipe Manufacturing Process.........................................38 Figure 17. Electric Resistance-Welding Process of the Pipe .........................................40 Figure 18A. Typical Electric Resistance-Welding Process............................................41 Figure 18B. Electric Resistance-Welding Process of the Pipe ......................................42 Figure 19. Typical Submerged Arc-Welding Process....................................................43 Figure 20. Nelson Chart For Selecting Carbon Steel And Low Alloy Steel per API Publication 941. ......................................................................................................51


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LIST OF TABLES Table 1. Corrosion That May Occur in All Piping Systems............................................24 Table 2. Common Corrosion Types In Plant Piping ......................................................25


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INFORMATION INTRODUCTION The previous module discussed the primary types of piping systems and the ASME/ANSI B31 codes that apply to them. This module reviews another early step in the design of a piping system, which is material selection. Selection of the appropriate material sets parameters for the other facets of piping design and is required to determine the allowable stresses for the design. In many cases, the material engineer will select the basic material chemistry, and material type that will be on the process diagram. However, if there are any modifications, the engineer will need to know how to select materials. This module discusses the factors that influence material selection, the methods of pipe manufacturing and their influence on material selection, and how to use SAES and SAMSS requirements to select material for components in a particular service. Achieving the objectives of this module requires the engineer to know the purpose and organization of SAES's and SAMSS's. The purpose of these standards was discussed in MEX 101.01. In selecting materials, the engineer must also have knowledge of the following: •

The basic principles of material science.

•

The type of piping system and applicable codes (covered in MEX 101.01).

•

The fluid characteristics (temperature, corrosivity, H2S content, etc.) obtained from the process engineer.

Several topics are not covered in detail. These topics are either infrequently used and the participant should already possess sufficient knowledge of the subject, or the topics beyond the scope of this introductory course. Should the participant wish to pursue these topics further; there are many resources that can be consulted. These include textbooks and other Saudi Aramco courses such as COE-101 “Corrosion Basics”, and COE-110 “Material Selection & Failure Analysis”. Because of the short time available for this course, this module will cover the applications and topics participants use most frequently.


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FACTORS THAT AFFECT MATERIAL SELECTION The Saudi Aramco engineer must recognize the factors that determine the applicable SAMSS's, and the concerns associated with particular services and the use of certain materials. Identifying factors that affect material selection helps the engineer make an optimal choice if more than one material is suitable. It also helps the engineer to specify appropriate SAMSS requirements based on fluid characteristics and additional information that is required in material selection (i.e., chemistry, product form). Several factors influence the selection of material for a particular piping service. The most important factors include the following: •

Mechanical Strength.

•

Corrosion resistance.

•

Suitability for wet, sour and hydrogen services.

•

Fabrication

•

Availability.

•

Cost.

A discussion of the first four of these factors appears below. The remaining two factors, availability and cost, are outside the scope of this course. The assessment of these factors will prepare the Saudi Aramco engineer for the materials selection process. Service environment and design conditions govern this process. However, Saudi Aramco Standards (SAES) and Material Specifications (SAMSS) govern selecting material for any Saudi Aramco facilities through the following steps: 1) Picking a basic material chemistry a) For piping refer to SAES-L-032, “Materials Selection for Piping Systems” and SAES-L-033. b) For fittings refer to SAES-L-007, “Selection of Metallic Pipe Fittings.” Saudi Aramco DeskTop Standards

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c) For valves refer to SAES-L-008, “Selection of Valves.” d) For flanges, gaskets and bolts refer to SAES-L-009, “Metallic Flanges, Gaskets and Bolts for Low and Intermediate Temperatures.” 2) Identify limitations on pipe and piping components from and SAES-L-006,” Metallic Pipe selection.” 3) Specifying the applicable of SAMSS's. 4) Use industry standards to determine material designations for piping components. This process has been already completed and put together as to make material selection easy and accurate in the standard SAES-L-005’” Piping Material Specification”. This process will be discussed in detail later in other sections of this module. In order to set the basic engineering understanding and the importance of the factors mentioned above, the following sections will provide more details on these factors.


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PHYSICAL PROPERTIES The mechanical strength of a material can be identified by the following mechanical properties: •

Yield strength.

•

Tensile strength.

•

Creep strength.

•

Toughness strength.

•

Hardness.

•

Fatigue strength.

Yield and Tensile Strength Engineering materials are selected for various applications on the basis of the physical properties of the materials. In construction, two of the most important properties that determine whether a material is appropriate for an application include tensile strength and yield strength. Design engineers compare the rated tensile strength and yield strength of candidate materials to the expected loads on the structural members of the projects they design. The material ratings must exceed the calculated loads with sufficient safety margins before they can be selected. Some information, such as Modulus of Elasticity, Yield Strength, Tensile Strength, Percent Elongation, Percent Reduction in Area, can be determined from a Stress-Strain Diagram produced by the standard tensile test. Using a sample machined to certain dimensions, a unidirectional load is applied to elongate or lengthen the sample at a constant rate. The load is usually applied until the sample fractures. The force or load to elongate the sample to failure is continuously measured during the test. A stress-strain diagram is produced from this standard tensile test, which is covered by ASTM A-370. A typical stress-strain diagram for steel is illustrated in Figure 1. It shows that as the stress in a material increases, its deformation also increases. Eventually a value known as the yield strength, Point A in Figure 1, is reached. This value is the stress that is required to produce permanent deformation in the material. If the stress is further increased, the permanent


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deformation continues to increase until the material fails. The maximum stress the material attains is known as the tensile strength and is shown by Point B in Figure 1. If a large amount of strain occurs in going from Point A to Point C, the rupture point, the material is called a ductile material. Steel is an example of a ductile material. If the strain in going from Point A to Point C is small, the material is classified as brittle. Gray cast iron is an ideal example of a brittle material. The Yield strength is defined as the stress required to cause permanent deformation in a metal or alloy. Since the stressstrain curves for many materials are smooth, there is no precise point at which elastic behavior ends and plastic behavior begins. By convention, the yield stress (often called the “proof stress”) is chosen as the stress corresponding to 0.2 percent offset strain on the engineering stress-strain curve, as shown in Figure 2. In design work, the yield strength of metals and alloys is of critical importance.

Figure 1. Typical Stress-Strain Diagram for Steel


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The ultimate Tensile strength of a metal or alloy is obtained by drawing a horizontal line from the maximum point on the stressstrain curve to the vertical stress values on the left. The value obtained is called the ultimate tensile strength, or just tensile strength. During a tensile test the material may fracture at this point or upon further loading the specimen may begin to neck down resulting in a reduction of tensile load prior to failure. Note how the stress values on the curve in Figure 2 begin to decrease after reaching the ultimate tensile strength. If the specimen necks down with a reduction in tensile load, the material is ductile. If little or no necking occurs prior to failure, the material is brittle and will fracture when the ultimate tensile strength is reached. Ductility of the material is an important mechanical property that must be considered during the selection of material. It is measured by Percent Elongation and Percent Reduction in Area.

80 0.2% offset yield strength

60

500

400

50 300

40 30

0.2% offset construction line

200

20 10

0

0.002 in. x 100% = 0.2% in. offset 0.002 0.004 0.006 0.008 0.010

Engineering stress, MPa

Engineering stress, 1000 psi

70

100

0

Engineering strain, in./in.

Figure 2. Yield Strength (0.2% Offset Proof)


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Creep Strength Both the yield and tensile strengths decrease as temperature increases and these strengths control the allowable stress that is used for piping component design at temperatures below the creep range. For a given stress, the strain in most materials remains constant with time at about or below 400°C (750°F). Above this temperature, even with constant stress, the strain in the material will increase with time. This behavior is known as creep. The temperatures above 400°C (750°F) are known as the creep range. Metals and alloys under continuous stress at elevated temperatures may deform by creep. Figure 3, Typical Creep Curve, shows the relationship between strain versus time for a tensile specimen under constant load at a constant elevated temperature. As shown in Figure 3, the three stages of creep are: •

Primary (decreasing strain rate)

•

Secondary (constant strain rate)

•

Tertiary (strain accelerates to failure).

From Figure 3it can be seen that the creep rate will vary during primary creep, will reduce to a smaller but relatively constant rate during secondary creep, and then will increase during tertiary creep until material rupture occurs. Allowable stresses for piping materials that operate at temperatures that are in the creep range are typically based on the material strength in the secondary creep stage where the creep rate is constant, and also on the stress at rupture.


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Figure 3. Typical Curve Showing Three Stages of Creep The creep strength, like the yield and tensile strengths, varies with temperature. For a particular temperature, the creep strength of a material is the minimum stress that will rupture the material during a specified period of time. For a specific stress level and temperature, the time-to-rupture is determined in a stress-rupture test. It is important to recognize that the time-torupture is strongly dependent upon the temperature and stress level of the material. The time-to-rupture increases as either stress or temperature or both are lowered. Conversely, if the temperature or stress level is increased, the time-to-rupture decreases. Stress-rupture data can be presented in either tabular or graphical form as shown in Figure 4. The data is generated by subjecting a series of material specimens to stresses at elevated temperature and measuring the time-torupture. The stress and temperature are held constant throughout the duration of the test. To allow extrapolation of rupture data out to 100,000 hours, tests are usually performed for at least 10,000 hours. Stress-Rupture curves are generated by plotting stress versus rupture time for each test temperature. The completed graph consists of a series of approximately


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parallel stress versus rupture time curves, with each curve representing a different test temperature. 100

600

Stress, 1000 psi

10

1

100 Stress, MPa

1200 F (6 00C) 1300 F (7 05C) 1400 F (7 60C) 1500 F (8 15C) 1600 F (8 70C ) 1700 F (925C ) 1800 F (980C ) 1900 F (1 038C) 2000 F (1095C )

10

1 01 1 10

1001.00

10.00

100.00 Rupture Life. h

Figure 4. Typical Rupture Strength of Incoloy Alloy 800HT, Also Effect of Temperature on Tensile and Yield Strength is Clear. Material Toughness Although a metal may be hard and have high tensile strength, it may not be able to withstand sudden impact loads. It is important to recognize that some materials are very susceptible to brittle fracture under conditions of impact loading. A good example of this is cast iron. Consequently, a very important property of a metal is toughness, which is a measure of its ability to absorb energy and deform plastically prior to fracture. Fracture of common carbon and low-alloy steels occurs in either shear or cleavage, which depends on the state of stress, the temperature, and the strain rate. The primary characteristics of these fracture types are as follows:


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Shear fracture, or ductile fracture, exhibits yielding and deformation and will occur at some point well beyond the Yield Point, refer to Figure 1.

Cleavage fracture, or brittle fracture, lacks the yielding and deformation that is found in a shear fracture. A cleavage fracture often occurs soon after first yielding of the material. Because brittle fracture occurs with little or no prior deformation, there is little warning before it occurs. Brittle fracture of materials must be avoided.

Charpy V Notch Testing Regular carbon steel pipe if it does not have enough capacity to absorb impact energy, cracks that may develop in a line pipe could propagate at the speed of sound until the crack is arrested or the energy driving the crack dissipate. Extensive studies were made to correlate Charpy V Notch value to the capacity of the line to arrest cracks. Figure 5shows a line pipe that was wide opened when the crack propagated. One way to characterize the fracture behavior of a material is the amount of energy that is necessary to initiate and propagate a crack in the material at a given temperature. This is known as the material's toughness. Tough materials require a relatively large amount of energy to initiate and propagate a crack. Brittle materials require less energy to initiate and propagate a crack.


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Figure 5. Line pipe rupture, crack propagated at the speed of sound Even though the area under the stress-strain curve gives an indication of toughness, the speed at which the force or load is applied and notch sensitivity must also be considered. Although there are a number of methods to measure toughness, the Charpy V Notch (CVN) test is one of the most commonly used. This test is illustrated in Figure 6. Using this machine, the toughness of the metal can be determined by measuring the energy required to fracture the sample. The amount of energy is usually specified in joules or ft-lbs.


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Figure 6. Charpy V Notch Testing Machine Effect of Temperature on Toughness Toughness as determined by impact tests is a very useful property in evaluating whether a metal will fail in a brittle or ductile mode. The toughness of BCC (body centered cubic) metals, which includes the ferritic steels, is adversely affected by low temperature. As the temperature is reduced, the toughness of the steel decreases. Further reductions in temperature will cause a change in fracture characteristics, from ductile to brittle. The temperature at which this change occurs is known as the ductile-to-brittle transition temperature. To avoid potential brittle fracture problems in equipment, plots of impact energy vs. temperature are generated for the steels used in fabrication. These “Transition Curves” are used to verify that the steels have adequate toughness at the minimum design metal temperature.


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As Figure 7shows, a material's temperature affects the amount of energy that is required to initiate and propagate a crack. The lower the temperature, the easier it is to have a brittle fracture in a material. The energy versus temperature curve that is shown in Figure 7has three zones: a brittle fracture zone, a transition zone, and a ductile fracture zone. The transition zone defines the temperature at which the material behavior changes from brittle to ductile. The beginning of the transition zone is normally taken at about 20 joules (15 ft-lb.) of absorbed energy. Brittle Fracture Zone

Transition Zone

Ductile Fracture Zone

Mixed Mode Behavior

Upper Shelf

Shear

Clevage

Difficult Crack Initiation and Propagation

Easy Crack Initiation 20 joules (15 ft.-lbs) Lower Shelf TEMPERATURE

Figure 7. Absorbed Energy Versus Temperature


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Effect of Carbon on Toughness Carbon has an adverse effect on the toughness property of carbon steel, the higher the carbon content in the steel the lower impact resistance (toughness) the steel will have. High carbon content has two detrimental effects on toughness. It raises the transition temperature, and lowers the maximum absorbed energy. This can be seen in Figure 8, Transition Curves for Steels. This figure shows the relationship between impact strength (energy) versus temperature for various carbon steels.

Figure 8. Effects of Carbon Content on the Transition Curves for Steel


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Effect of Heat Treatment and Grain Size Heat treatment affects both strength and toughness. Heat treatment will improve the toughness properties of steel. However, as the yield strength increases, the effectiveness of heat treatment on toughness decreases. Steels with a small grain size (fine-grained) must be used for low-temperature pipe, as required by 01-SAMSS-036. Effect of Chemical Composition or Alloying Elements The major chemical elements that affect a material's toughness and their effect are as follows: •

Manganese.

This element improves the material's toughness when used in concentrations of up to 1.4%. 01-SAMSS-036 contains requirements for carbon-manganese steel pipe in lowtemperature service. •

Nickel.

This element significantly increases the toughness of a material. Up to 3% nickel is allowed by 01-SAMSS-036 for pipe. However, for sound service, the nickel content must be less than 1% per NACE MR-01-175. •

Oxygen, Sulfur, Molybdenum.

These elements have a detrimental effect on a material's toughness. The amount of each of these elements is controlled in steels that require good toughness qualities. Fully deoxidized steel is required for pipe based on 01-SAMSS-036.


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Fatigue Strength The fatigue strength is an important strength factor that influences material selection. The fatigue strength is important for piping systems that experience either mechanical or thermal cyclic loading. A piping system that contains a reciprocating pump or reciprocating compressor is an example of a piping system that experiences cyclic loading. Figure 9 shows the allowable fatigue stress (Sa) versus the number of loading cycles for materials that would include ASTM A106, Gr. B carbon steel seamless pipe. The allowable fatigue stress decreases as the number of cycles increase. Piping systems must be designed such that a fatigue failure will not occur during their design life.

Figure 9. Design Fatigue Curve


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Effects of Hardness Engineering materials used in many construction applications are subjected to indenting stresses, which could potentially result in structural failures. For these applications, designers evaluate the hardness of candidate materials to determine whether the materials are suitable for use. The hardness property of a material is a measure of its ability to resist deformation by an indenter. Hardness data are often used to assess a material’s ductility. In general, for a given material the lower the hardness the greater the ductility. To perform a hardness test, a known load is applied to an indenter (spherical, pyramidal, or conical) in direct contact with the metal surface. The dimensions of the resulting indentation are measured and the data converted to provide an indication of hardness. The most commonly used hardness measurement methods include Brinell, Vickers, Rockwell, Knoop, and Shore.

Fabrication For a material to be useful in the construction of a piping system, it must be available in the shapes or forms that are required. In piping systems, some common shapes and forms include the following: •

Seamless pipe.

•

Plate that is used for welded pipe.

•

Wrought elbows, tees, reducers, and crosses.

•

Forged flanges, couplings, and valves.

•

Cast valves.

For welded pipe, the used plate must be ductile enough to permit rolling. For cross-country pipelines, the material must be ductile to allow bending during construction to conform to moderate changes in elevation or lateral end points.


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The weldability of materials includes consideration of the effect of welding on the following material properties: •

Reduction in strength.

•

Reduction in toughness or ductility.

•

Increase in hardness of the weld and the heat-affected zone (HAZ).

•

Inducement of residual stresses.

•

Risk of stress-corrosion cracking.


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CORROSION RESISTANCE Corrosion of materials involves the destruction of the metal by chemical or electrochemical attack. Corrosion of materials takes many forms. Table-1 briefly describes some of the most common forms of corrosion that may affect all piping systems. Table-2 describes the forms of corrosion that are present mainly in plant piping systems, which are usually associated with the higher temperatures and greater concentrations of corrosive substances that occur in plant piping. The methods that are used to protect piping systems from the effects of corrosion depend on the type of piping system. Buried liquid and gas transportation piping systems are usually coated and have cathodic protection systems installed to prevent external corrosion. Also, coatings are sometimes used to protect against internal corrosion, or corrosion inhibitors may also be used to protect against internal corrosion. During the design, transportation piping should not be designed to be corroded due to the high initial investment cost in the material and installation and due to complexity and high cost for replacement and repair. For plant piping systems that are in corrosive service, the protection against corrosion usually comes by using alloys that resist corrosion. The most common alloys that are used for this purpose are chromium and nickel. Low-alloy steels, with chromium content of 1-1/4% to 9%, and stainless steels, increase corrosion resistance for a large number of environments. A notable exception is austenitic stainless steel in an environment that contains chlorides or polythionic acid where stress-corrosion cracking may occur. Selecting a resistant alloy, modifying the corrosive environment, and lowering or removing chlorides overcome cracking problems.


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Table 1. Corrosion That May Occur in All Piping Systems Characterized by a uniform metal loss over the entire surface of General or the material. Uniform corrosion could be accelerated if Uniform Corrosion combined with erosion which continuously removing the protecting oxidized layers. Erosion is another kind of metal loss due to high-velocity fluids, Erosion or moving fluids that contain abrasive materials such as sand. Most of the time erosion happens at preferred directions and locations such as elbows, turns and obstructions. Pitting A form of localized metal loss randomly located on the material Corrosion surface. Occurs most often in stagnant areas or areas of lowflow velocity, particularly under deposits. Occurs when two dissimilar metals contact each other in a Galvanic corrosive electrolytic environment. One of the two metals, Corrosion known as the anodic metal corrodes whilst the other “cathodic” material does not corrode. Electrons flow from the anode to the cathode through the material A localized corrosion that is similar to pitting. Crevice corrosion Crevice Corrosion occurs at places such as gaskets, lap joints, and bolts, where a crevice can exist. This type of corrosion affects materials that are generally noted for resistance to uniform corrosion. Occurs when the material experiences high cyclic stresses in Corrosion Fatigue the presence of a corrosive environment. The cyclic stresses initiate small cracks in the metal surface. Corrosion occurs rapidly at the crack tip, which is anodic, because the anodic area is much smaller than the crack sides and the outer surface, which are cathodic. Occurs in cast iron that is exposed to salt water or weak acids. Graphitic The iron in the cast iron corrodes away, and leaves the Corrosion graphite in place. The result is a material that is extremely soft but shows no apparent metal loss. Hydrogen Occurs when atomic hydrogen at a high temperature and Blistering and pressure diffuses into steel and collects at discontinuities. The Hydrogen Induced atomic hydrogen then forms molecular hydrogen. Since Cracking molecular hydrogen will not diffuse through steel, pressure builds up inside the voided area and causes rupture of the metal in a local area. The ruptured area appears as a blister on the surface of the metal.


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Stress Corrosion

Occurs when the material contains high applied or residual tensile stresses in the presence of a corrosive environment. Stress corrosion results in small-localized cracks that have little, if any, ductility.

Table 2. Common Corrosion Types In Plant Piping A high-temperature reaction that occurs between certain material alloys in an environment that contains compounds Carburization such as carbon dioxide or methane. The carbon is absorbed on the surface of the metal and diffuses inward. This results in loss in ductility, weld ability, and creep strength. Occurs in an oxidizing or reducing environment in the absence of carbon in the atmosphere. In decarburization, Decarburization carbon in the steel combines with oxygen or hydrogen to form carbon monoxide or hydrocarbons. The diffusion of the carbon out of the steel leaves the steel softer and weaker. A metallurgical behavior that occurs in carbon and lowGraphitization alloy steels at temperatures above 450°C (800°F). When this occurs, the carbon that is normally present in steel as Fe3C is gradually converted to graphite. Occurs when hydrogen diffuses into steel and reacts with High Temperature iron carbides to form methane. The methane then collects Hydrogen at grain boundaries, and causes high intergranular Embrittlement stresses, which ultimately leads to fissuring of the metal at the grain boundary. Occurs when the material contains high applied or residual tensile stresses in the presence of a corrosive Stress Corrosion environment. Stress corrosion results in small-localized cracks that have little, if any, ductility. A reduction in the toughness of low-chrome alloys (below Temper 3% chrome) that are exposed to temperatures above Embrittlement 400°C (750°F). Generally attributed to a weakening effect caused by segregation at grain boundaries of elements that are present in trace quantities.


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Suitability for Wet, Sour Service In the hydrocarbon industries, the material selected should be suitable for wet sour service because the damage that could occur in such service is sometimes catastrophic. In order to identify whether the service is wet sour or not, SAES-L-033 provide the criteria in this matter. SAES-L-033 contains general corrosion protection requirements for pipelines and plant piping systems and provides the specific requirements for welded line pipe in wet, sour service. Examples of wet sour services are the following: •

Wet-sour gas.

•

Wet, sour, multiphase service.

•

Wet-sour crude or condensate.

•

Sour water.

•

Dry-sour gas, where a process upset could result in water entering into or forming in the pipe.

The form of damage to the material due to hydrogen could occur in one or more of the following forms listed below. Figure 11 shows typical failure due to HIC. •

Hydrogen Blistering

•

Hydrogen-Induced Cracking (Stepwise Cracking) (HIC)

•

Sulfide Stress Cracking (SSC)

Saudi Aramco Standard 01-SAMSS-016 sets the requirements to insure that carbon steel line pipe purchased is HIC resistant. These requirements provide acceptance criteria for the following: Material Composition, Hydrogen Induced Cracking (HIC) Sensitivity Tests, and Nondestructive Testing.


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Hydrogen Blistering Hydrogen blistering is localized deformation of a metal. Some metal structures contain voids, inclusions, and other defects. When hydrogen atoms diffuse through metal, some of them collect at these defects. Hydrogen blistering occurs most often in low-strength steels that have high sulfur content. Hydrogen blistering occurs when hydrogen atoms combine to form hydrogen gas inside voids or at defects in a metal. Figure 10 show hydrogen blistering occurs in the wall of a tank. The exterior of the tank is exposed to the atmosphere. The interior of the tank contains an acid electrolyte. Hydrogen atoms are present on the interior surface. They are produced by corrosion reactions between the acid electrolyte and the metal. Diffusion of hydrogen atoms into the steel tank wall is promoted by sulfides in the acidic water. Within the metal, the hydrogen atoms combine to form hydrogen gas at a void or other defect. The hydrogen gas molecules are too large to diffuse through the metal. Therefore, hydrogen gas becomes permanently trapped at the defect.

Figure 10. Hydrogen Atom Diffusion Through the Steel Wall


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Tremendous pressure builds up as hydrogen gas gathers within a void. This causes large blisters to form; however, hydrogen blisters seldom lead to rupture of metal walls and they rarely cause brittle failure. Low-strength steels of poor quality are susceptible to hydrogen blistering. Figure 11 shows typical Hydrogen blistering developed in a line pipe.

Figure 11. Typical Hydrogen Blistering and HIC in the Wall of a Tank.


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Hydrogen-Induced Cracking (Stepwise Cracking) Hydrogen-induced cracking (HIC) occurs when microscopic blisters form at inclusions and other discontinuities, i.e., grain boundaries. It occurs in low-strength steels in wet sour service. Low strength steels (tensile strength < 90,000 psi) are used to make piping, vessels, and tanks. Wet sour service includes hydrocarbon streams that have a separate water phase, which contains at least 50 ppm H2S. Saudi Aramco has also experienced HIC in pipelines in wet sour gas service. Hydrogen is produced by the corrosion of steel in wet sour environments. The steel absorbs some of the hydrogen atoms. Atomic hydrogen accumulates at non-metallic inclusions and other discontinuities. At these defects, hydrogen atoms combine to form molecular hydrogen. Molecular hydrogen is too large to pass through the steel. It becomes trapped and forms small blisters. As the concentration of hydrogen increases, the pressure inside the blisters builds up. Stepwise cracking occurs when short blisters at varying depths within the steel link together to form a series of steps. The cracks may reach the surface and cause the metal to fail. Figure 12 and Figure 13 shows a typical failure in a line pipe due to HIC.

Manufacturing practices greatly influence the sensitivity of steels to HIC. Hydrogen cracking sensitivity tests by Saudi Aramco show that HIC susceptibility is a function of composition and deoxidization practice. The most important factor that affects HIC sensitivity of steels is the structure of any manganese sulfide (MnS) inclusions. Steels with elongated MnS inclusions are the most susceptible to HIC. HIC is more likely in steels that are deoxidized with silicon (Si) or aluminum (Al) because Si and Al deoxidizers change the shape of the sulfide inclusions and determine the temperature at which the sulfur comes out of solution. Si and Al deoxidizers are used in fully killed steels. Semi-killed steels, in which MnS remains in globular form, appear to be less susceptible to HIC. The shape of MnS is now being controlled with calcium. The rolling process and the addition of steel alloy elements also influences the structure of MnS inclusions.


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Figure 12. Stepwise Cracking of a Low-Strength Pipeline Steel Exposed to H2S

Figure 13. Stepwise Cracking of a Low-Strength Pipeline Steel Exposed to H2S


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Sulfide Stress Cracking Hydrogen diffusion into a metal can cause the metal to loose ductility and tensile strength. This can result in sudden failure with only a little loss of metal. Sulfide stress cracking (SSC) affects high-strength carbon steels with hardness above 22 Rockwell C in sour oil field environments. Other alloys have different hardness limits in sour environments. SSC is a special case of hydrogen stress cracking, which may also be referred to as hydrogen embrittlement. Sulfide stress cracks may begin at surface notches or pits on the metal surface as shown in Figure 14. Cracks can also begin within the metal at discontinuities or defects such as inclusions, carbides, or grain boundaries. Both tensile stresses and hydrogen entry into the steel are required for SSC to occur. Hydrogen enters the steel when the metal corrodes in sour oil field waters. Hydrogen entry may be increased by cathodic protection in sour environments. We do not know the exact interaction between hydrogen atoms and the metal structure that causes SSC. We know that SSC is related to stresses in the metal. SSC does not occur below a certain threshold stress for a particular metal structure. Increasing the hydrogen pressure within the metal increases the chances for SSC. Also, SSC is most likely to occur at temperatures of about 20°C (70°F). Failures due to SSC do not always occur rapidly.


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Figure 14. Mechanism of Sulfide Stress Cracking Stress Corrosion Cracking Stress corrosion cracking (SCC) is caused by a combination of localized corrosion and metal tensile stress. Nearly all metals are susceptible to SCC in certain environments. For example, stainless steels may crack in chloride solutions. Ordinary steels are susceptible to SCC in hot solutions that contain high hydroxide concentrations or carbonates and bicarbonates. Figure 15 shows a case of line pipe failure due to SSC, which starts externally.


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Corrosion product film

M 2+

Metal

M 2+

Tensile

Tensile

Forces

Forces advancing crack

Cracks developing in the parent metal due to external SCC

Cracked pipe due to SCC

Figure 15. External Stress Corrosion Cracking in a Line Pipe


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AVAILABILITY AND COST After discussing the basic engineering aspects that would direct the selection of a specific material, now we consider two interrelated items, which are availability and cost. When a material is selected, the engineer should plan ahead if that particular material is not readily available. As an example regular Carbon steel pipe grade B are most of the time are readily available. In the other hand, high alloy steel may not be readily available. Therefore, lead-time for material procurement must be considered. Cost is one of the most important factors, after safety that must be considered. There are exotic materials, which will perform perfect in the environment, but their cost may not be justified for the life cycle of the piping system. Also, a material could be cheap as initial cost, but its maintenance cost and downtime associated wit the extended maintenance could counteract the initial cost savings.


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PRIMARY PIPE MANUFACTURING PROCESSES A description of pipe should include the manufacturing process. When the engineer is selecting material, the pipe manufacturing process will help him determine the potential overall quality of the pipe. Because of the hazards with some fluids, certain manufacturing processes are prohibited. The Saudi Aramco engineer needs to determine the most suitable pipe manufacturing process for a piping system. Prohibited manufacturing processes are specified in SAES-L-006. Metallic line pipes are usually manufactured using one of the following five processes: •

Seamless pipe.

•

Electric resistance-welded pipe (HFW).

•

Submerged arc-welded pipe.

•

Spiral-welded pipe.

•

Furnace-welded pipe.

The quality of the manufacturing processes varies, with seamless pipe having the probability of fewest defects and furnace-welded pipe the worst. A brief description of each process follows.


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Seamless Pipe Seamless pipe is one of the oldest methods for manufacturing line pipe. A schematic diagram of the process is shown in Figure 16. The hot, rotary piercing process is usually used to produce seamless pipe as follows: 1. The pipe starts as a round billet of high quality, killed steel. 2. The billet is heated to a forging temperature of 1,2001,315°C (2,200-2,400°F), and forced over the rounded nose of a hardened piercing mandrel. This gives a thick-walled tube. 3. A plug or ball is inserted in the pierced hole. 4. The tube then passes through a series of rollers that shape the billet to the final outside diameter of the pipe and reduce its wall thickness to the desired value. 5. Finally the pipe goes through beveling machine and hydro testing.


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Figure 16A. Typical Seamless Pipe Manufacturing Process


37



Figure 16B. Typical Seamless Pipe Manufacturing Process


38



Electric Resistance-Welded Pipe Electric resistance-welded pipe typically is another manufacturing process to produce line pipes. The welded pipe usually begins as a plate and goes through several steps until finally become an acceptable pipe. Figure 18 shows a schematic diagram of the manufacturing process for pipe of 24” and smaller. The flat plate becomes a pipe through several steps that may include rolling or forming, tack welding, final welding, cold expanding, end beveling, and external and/or internal coating. A typical operation for a largediameter pipe would include the following steps: 1. A plate of the proper thickness is sheared to the desired width and shot-blasted or pickled. 2. A set of dies is used to first form the plate into a "U" shape. The U-shaped plate is then formed into a circular shape with a second set of dies. 3. Alternatively, the plate is rolled into the circular shape. 4. The circular shape is then welded into a pipe. The welding machine has adjustable rollers that force the open edges of the formed plate together. It also has two circular electrodes to place a current across the gap between the open edges of the plate. The current across the edges heats the metal while the rolls force the edges together to complete the weld under pressure. Figure 17shows conceptually what happens in the welding machine 5. While the weld is still hot, the pipe passes between rollers and over a mandrel to smooth the weld area and remove the extra weld metals. 6. The pipe is sized, as it is cold-contracted to its final outside diameter and wall thickness. 7. The ends of the pipe are beveled as required. Then it passes through beveling the hydro testing stand. 8. Finally the pipe is externally coated or internally lined, as required.


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9. Inspection of the product usually occurs at various steps throughout the process of changing a plate into a pipe. Generally ERW pipe are cheaper and faster to produce than the seamless pipes because the production process requires less energy and the forming machinery’s last longer. The dimension control of ERW could be close to perfect. However, manufacturing quality controls and inspection procedures to identify defects are very critical to insure high quality pipes. The nature of manufacturing of ERW pipe could lead to gross defects in the weld seam where lack of fusion is always possible as shown in Figure 18. Saudi Aramco standard SAES-L-006 allows using ERW line pipe for pipelines but it prohibits the use of ERW pipe for hazardous service for plant piping.

Figure 17. Electric Resistance-Welding Process of the Pipe


40



Figure 18A. Typical Electric Resistance-Welding Process


41



Figure 18B. Electric Resistance-Welding Process of the Pipe


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Submerged Arc-Welded Pipe The submerged arc-welding process is the most common for manufacturing carbon steel pipe. Pipe that is made through the use of the submerged arc welding (SAW) process also goes through a welding machine. Figure 19 illustrates the process. With this process, the open ends of the formed plate have either a single (single-submerged arc, SSAW) or double (doublesubmerged arc, DSAW) bevel. While rollers force the beveled edges together, a consumable electrode adds metal to the weld. A blanket of granulated flux covers the arc and the molten metal. The flux creates a protective atmosphere and a slag that shields the weld metal until it solidifies. If required, the internal bead is ground flush with the inside surface of the pipe. Electric resistance-welded pipe and submerged arc-welded pipe are high-quality pipes that are suitable for most services. Most cross-country pipelines consist of one of these two types of pipe. Since they contain a longitudinal seam, however, they may not be as high a quality as seamless pipe. The joint quality factor for these two processes is usually taken between 0.8 and 1.0, depending on the piping design code, the material specification, and the degree of inspection.

Figure 19. Typical Submerged Arc-Welding Process


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Spiral-Welded Pipe Spiral-welded pipes are made by winding narrow coils of steel into cylinders with the edges forming a helix. Then, the edges are welded together using either double-submerged arc-welds, which is more common, or using High Frequency/ Electric resistance. Spiral-welded pipe is used primarily for crosscountry pipeline services, where the specifications and weld details that are used result in a joint quality factor of 1.0. SAESL-006 prohibits the use of spiral-welded pipe for hazardous services, unless it is manufactured and tested in accordance with an applicable SAMSS.

Furnace-Welded Pipe Furnace-welded pipe is generally the lowest cost (and lowest quality) pipe that few oil industries permit using in their facilities. The process that is used to make furnace-welded pipe is similar to that used for ERW pipe. The free edges of formed plate are forced together and heated in a furnace. The heat causes the free edges to fuse together. The quality of the welded joint is not as high as in the ERW or SAW processes. SAES-L-006 prohibits the use of furnace-welded pipe for hazardous services.

Joint Quality Factor Different pipe manufacturing type would produce different quality of pipe. Therefore, piping Codes assign a factor that represent a safety factor in relation to the type of manufacturing and the risk involved with the particular piping system. This factor is called Joint Quality Factor. This joint quality factor is assigned to the pipe during the design stage to calculate the required wall thickness. This factor is a measure of the quality of the manufactured pipe. It is dependent on the piping manufacturing process and the level of inspection conducted over the pipe joint. Also, this factor is code dependent. The highest possible value for this factor is 1.0 and it could be as low 0.6 for furnace welded pipes. Because there is no seam in the seamless pipe the joint quality factor is 1.0. Spiral-welded has a joint quality factor of between 0.75 and 1.0, which depends on the material specification and welded joint detail as well as the applicable code. The usage of this factor is addressed more in MEX-101.03.


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SAUDI ARAMCO LIMITATIONS ON METALLIC PIPE Material selection process is a result of many years of collective experiences accumulated by Saudi Aramco as well all other petrochemical industries and pipeline operators. Also, research for new development of new products and new manufacturing processes is a continuous activity. Various companies would have relatively different approach to using material for a specific service. In general, Saudi Aramco approach lean to the conservative side when it comes to material selection. This conservative approach is found in the extra specifications imposed on common industry practice. SAES and SAMSS General Limitation Saudi Aramco engineer must be familiar with requirements of SAES L series and the SAMSS 01, 02 and 04 classes, because these standards are the starting point for selecting material to be used in Saudi Aramco facilities. The industry Codes allow broader range of materials and sometimes less tight requirements, therefore, in addition to the minimum requirements of the industry Codes and Specification, SAES and SAMSS have added more stringent requirements. The limitation will be related to one or more of the following topics: •

Limitation on specific grades and materials, either for inventory purposes or to avoid technical problems with some grades or due to lack of confidence and experience in a specific grade.

•

Limitations on usage of specific manufacturing processes into specific service or a facility.

•

Extra limitation on the chemistry of the carbon steel line pipe, in particular the carbon content equivalent and other alloying elements.

•

Limitation on the operating range of some materials, that otherwise will be used for different range per industry practices.

•

Limitation with the objective to be in the more conservative side in order to avoid potential risks that its consequences


45



far exceed the initial savings. These risks could involve people life, environmental impact and huge capital damages. •

Historic limitations that have been introduced into the standards and specification based on a single incident. Maybe, the reasons for the specification are not applicable any more, but revision to this requirement has not been made, because people tend to accept thing as they are without and try to avoid the effort to change them.

We should note that, the material industry is improving and the standards keeps changing, therefore, the engineers should always refer to the latest editions of the standards and consult with the material and piping engineers for the latest. In the following sections important issues will be highlighted for their importance in relation to material limitations imposed by Saudi Aramco. SAES-L-006 is the standard in L series that impose limitations on the usage of metallic piping. Some of the limitations are also imposed in SAES-L-005. Following sections provide guidelines about some of the major limitations that should be emphasized and understood by those involved in piping material selection. Pipe Grade Specified Minimum (SMYS) The Saudi Aramco line pipe is standardized on two grades ASTM A106 or API 5L Grade B and API 5L Grade X60. This limitation applies to stocked line pipe in the Saudi Aramco Material System (SAMS). The main purpose for this is to limit the inventory and avoid mixing up grades. Also, higher-grade pipe would require more stringent requirement for field welding, which would add more cost during construction. However, if there are enough economical justifications to use higher grade such as X65, the Standards do not completely prohibit doing so. Pipe Size In order to reduce the inventory and to insure availability, SAESL-006 requires that pipe outside diameters must be in accordance with API Specification 5L. Intermediate sizes and the sizes 1/8, 1/4, 3/8, 1-1/4, 2-1/2, 3-1/2, and 5 inches shall not be used except when necessary to match vendor equipment connections. Pipe sizes smaller than 3/4 in. shall not be used


46



for hazardous services (including vents and drains) except for instrument connections and on vendor-supplied, skid-mounted equipment or other applications when in the pipe is protected against mechanical damage. Manufacturing Process of Line Pipe SAES-L-006 also states the following limitations. •

Iron pipe specifications shall not be used for hazardous services and only steel pipe specifications shall be used to handle flammable fluids.

•

HF/ERW line pipe shall not be used in on-plot piping, due to the high risk and consequences if a catastrophic failure occurs. Also, there are no economic incentives for using ERW pipe inside plant area.

•

Furnace butt-welded pipe shall not be used for hazardous service.

Low Temperature Limitation on Line Pipe & Components As discussed in earlier section, carbon steel pipe behave differently at low temperature condition, therefore more control over the material has been specified when the line pipe will be considered operating at low temperature. The main points to be understood in this matter are the following: •

For transportation pipelines in gas, liquefied gas, and multiphase services, the requirements of 01-SAMSS-022 shall be applied for fracture control.

•

For in plant piping, temperature below –18°C is considered low temperature even though ASME B31.3 specifies below 20° as low temperature.

•

Therefore, pipe in accordance with 01-SAMSS-036 shall be used when the design minimum temperature is between 45°C and -18°C (-50°F and 0°F). 01-SAMSS-033 imposes additional requirements that are aimed at improving the toughness properties of pipe in low-temperature services.


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•

•

•

Pipe in accordance with specifications listed in ASME/ANSI B31.3, with a minimum temperature of -45°C (-50°F), maybe used when the design minimum temperature is between 29°C and -18°C (-20°F and 0°F). This requirement forces the pipe material to have better toughness properties than would otherwise be needed at temperatures between -29°C and -18°C (-20°F and 0°F). Pipe in accordance with 01-SAMSS -035 can be used when the design minimum temperature (as defined in SAES-L002) is at -18°C (0°F) and above. Also, there other exceptions to the impact testing listed in SAES-L-006. However, these are always subject to change and review. An example is that impact testing is not required when the design minimum temperature is below -18°C (0°F) but at or above -29°C (-20°F), and if: - The maximum operating pressure of the pipe will not exceed 25% of the maximum design pressure allowed by ASME/ANSI B31.3 at ambient temperature, and, - The combined longitudinal stress due to pressure, dead weight, and displacement strain does not exceed 41.4 MPa (6,000 psi) for any temperature within this range.

Industry experience has found that brittle fracture is not a concern unless the stress levels in the pipe are above these values. Therefore, impact testing is not necessary. The mechanical design of the piping system would have to be very conservative in order to meet these requirements.


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MATERIAL SELECTION PROCESS The material selection process for Saudi Aramco piping system is already defined and almost completed to be directly used for specifying the adequate material for the service and application. The final product of an accumulative experience by Saudi Aramco and other Industries in the area of selecting material is summarized in the standard SAES-L-005, Piping Material Specification. This standard provides all piping material required for a specific piping system to a specific service. More details will be discussed on this standard later in this section. However, for completeness and better understanding of the basis of the SAES-L-005, the general engineering practices followed in the material selection process must be explained. The material selection process requires the following steps: 1. Identify the piping system whether it is transportation, process plants or utilities. Accordingly the applicable piping Code, ASME B31.1, B3.3, B31.4 or B31.8 will be defined. This has been covered in MEX 101.01. 2. Identify the service in terms of fluid type, temperature and presence of air. These will be given by process engineers. 3. Select a basic material chemistry from the applicable as follows: a) Line pipe: SAES-L-032, Material Selection of Piping Systems b) Valves: SAES-L008, Selection of Valves c) Fittings: SAES-L-009, Metallic Flanges, Gaskets and Bolts for Low and Intermediate Temperature service. 4. Identify the applicable Saudi Aramco standards, SAES’s and SAMSS's, and the applicable industry standards and specification. 5. Designate a material specification using industry and Saudi Aramco standards.


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Basic Material for Pipe Systems, SAES-L-032 The starting point as far as knowing the basic material composition is SAES-L-032. As stated earlier, the service environment and the design conditions govern the selection of the basic material chemistry. These are detailed in Table 1of SAES-L-032 as shown in Addendum C. This table contains a list of service environments, design conditions, and basic material chemistry. The required service environment and design conditions will be known information that is based on the specified process design requirements. This information will consist of the primary service fluid and its concentration, design temperature, whether air is present or not, and the fluid flow velocity. Table 1 of SAES-L-032 is then entered with this information, and the basic material that is required for the pipe and piping components other than valves is selected. An equivalent or better material may also be used, subject to the approval of the assigned engineering specialist in the Consulting Services Department. For service conditions, which differ from those, that are listed, the assigned engineering specialist must be consulted. Sample problems 1 and 2 will show are examples of how to use this table. There are some specific design conditions and service type that has no material specified in the Table-1 of SAES-L-032, but referral to Nelson Chart id dictated. The following section provides some guidelines on how to use this chart. Nelson Chart for Hydrogen Service For high temperature hydrogen service, the Nelson Chart from API 941 is used. Hydrogen attacks the metal differently from other corrosive substances as explained earlier in this module. API 941 Publication Steels for Hydrogen Service at Elevated Temperature and Pressure in Petroleum Refineries and Petrochemical Plants provides guideline on steel selection for such service. The Nelson Chart provides the means for selection the material based on the temperature and the Hydrogen partial pressure. The Nelson Chart, shown in Figure 20, contains curves for various material chemistries. These curves show the maximum combination of temperature and


50



hydrogen partial- pressure permissible. Use of a material at conditions that are above its curve could result in hydrogen embrittlement and eventual failure. To use the Nelson Chart, the design temperature and hydrogen partial pressure must both be known. After plotting the two values on the Nelson Chart, the basic material to use is the one associated with the curve above the plotted point. For example, the point for an environment that contains hydrogen at a temperature of 371°C (700°F) and a hydrogen partial pressure of 10.34 MPa (absolute) (1,500 psia) is shown plotted as Point A in Figure 20. The line above Point A is the one for 2.25 Cr 1.0 Mo Steel. Thus, this would be the basic material chemistry needed to prevent material damage due to hydrogen attack. Sample Problem-3 will illustrate how to use it.

A

Figure 20. Nelson Chart For Selecting Carbon Steel And Low Alloy Steel per API Publication 941. Several items should be noted with respect to the material chemistries that are shown on the Nelson Chart. •

Material chemistries C-0.25 Mo, C-0.5 Mo, and 1.0 Cr-0.5 Mo are shown. Neither C-0.25 Mo nor C-0.5 Mo materials would be used in a hydrogen environment since there is concern about their long-term reliability even at conditions


51



that are within their Nelson Chart limits. The 1.0 Cr-0.5 Mo material is often not readily available. Therefore, from a practical standpoint, if carbon steel is not acceptable for the specified conditions, the first higher alloy material that would be considered is 1.25 Cr-0.5 Mo. •

A 2.0 Cr-0.5 Mo material is shown above the 1.25 Cr-0.5 Mo curve. This material would not be specified for the same reason that the 1.0 Cr-0.5 Mo material is not used. Therefore, if 1.25 Cr-0.5 Mo material is not adequate for the specified design conditions, the 2.25 Cr-1.0 Mo material would be the next alloy considered.

•

The material cost on a per pound basis increases as the alloy content increases. Therefore, the lowest alloy material that is acceptable for the specified design conditions should be used.


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Sample Problem1:

SAES-L-032 - Crude Pipeline A pipeline will transport crude oil cross-country at a temperature of 80°C (176°F). No air will be present in the crude oil. To select the basic chemistry of the piping material: 1. Go to SAES-L-032, 2. Table 1 (Addendum C). Then look for "Crude Oil or Products" under the first column, heading "ENVIRONMENT”. You will be directed to go to “Hydrocarbon”. 3. Next, move to the right to the column headed "TEMP DEGREES C" and check that the fluid temperature is below the maximum permitted. Because this is the case, move to the right to the column heading "BASIC MATERIAL". 4. The basic material is carbon steel. 5. The "REMARKS" column references paragraph 4.4. Paragraph 4.4 of SAES-L-032 provides the requirement for all material in wet, sour service. For example, the material must meet the requirements of NACE Standard MR-01-75. This is to insure that the material will be resistant to Hydrogen Induced Cracking (HIC) and Stress Sulfide Cracking (SSC).


53



Sample Problem 2:

Steam Line

Piping in a refinery will contain process steam at a temperature of 450°C (842°F). No air will be present with the steam. To select the basic chemistry of the piping material: 1. Go to the line "Steam" under the first column of SAES-L-032, Table 1 (Addendum C-1). Move to the right. There are three temperature ranges listed. The steam in this case is in the third temperature range, 400-500°C (752-932°F). 2. Move across to the right on the line that contains this temperature range. Under the heading "BASIC MATERIAL," the basic piping material is 1-1/4 Cr – 1/2 Mo alloy steel. 3. There are no additional considerations in the "REMARKS" column in this case.


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Sample Problem 3:

Nelson Chart

Piping in a refinery will contain hydrocarbon with hydrogen at a temperature of 371°C (700°F). No air will be present with the steam. The Hydrogen partial pressure is 2200 psig. Select the proper material for the service. To select the basic chemistry of the piping material: 1. Go to SAES-L-032, Table 1 (Addendum C). Then look for "Hydrocarbon gas with hydrogen" under the first column, heading "ENVIRONMENT”. 2. Next, move to the right to the column headed "TEMP DEGREES C”. There is no temperature limits specified. 3. Under the Basic Material Column, the note states “ Per Nelson Chart’. 4. The "REMARKS" column references API Publication 941. 5. Using Nelson Chart, Figure 20, the basic material is low alloy carbon steel, 2.0 Cr 0.5 Mo Steel. 6. However, due to the fact the above material is not available, the next higher low alloy carbon steel shall be used which is 2.25 Cr 1.0 Mo.


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Basic Material for Valves, SAESL-008 Similar to the procedure for selecting material for pipe and fittings, the starting point for selecting the basic material composition for valve body and components is SAES-L-008, Valves Selection. This Standard contains tables similar to those in SAES-L-032. An extract of the table is shown Addendum C. The valves types, selection and testing will be discussed in more details in MEX-101.06.


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Sample Problem 4:

Valve Selection

A valve is required to be installed on a piping system at a gas plant. The service is ADIP (Amino Diisoppropanol), with 25% concentration and design temperature of 100 °C (212). To select the basic chemistry of the valve body and trim material: 1. Go to SAES-L-008 Table 1 (Addendum C). Then look for " Amino Diisoppropanol " under the first column, heading "ENVIRONMENT”. 2. Next, move to the right to the column headed "TEMP DEGREES C”. The 100 °C is within the range. 3. Under the Valve Material Column: 4. The valve body material is carbon steel 5. The valve trim material is 316 SS 6. The "REMARKS" column states that no copper alloys allowed.


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Determining Applicable SAES and SAMSS for Pipe and Piping Components Saudi Aramco and industry standards specify material requirements for pipe and piping components. A complete material specification needs to include the applicable industry standard. The Saudi Aramco engineer must determine the standard that governs the design and fabrication of the particular component. This determination will allow him to designate the industry standard that is applicable to a component for a particular service, and specify the SAES's and SAMSS's that give additional requirements. Saudi Aramco specifies materials requirements in the Saudi Aramco Engineering Standards (SAES's), the Saudi Aramco Materials System Specifications (SAMSS's), and in Mandatory Saudi Aramco Standard Drawings. These standards serve two purposes, first they set the acceptable Industry Standards for Saudi Aramco pipe and pipe fittings, also, and they provide additional requirement to those Industry Codes and specifications. Addendum A gives listing of the Saudi Aramco SAES's and SAMSS's that apply to pipe, valves and piping components. The scope of each standard is shown in the table. Industry Standards for Pipe and Piping Components The ASME/ANSI B31 piping codes each provide a list of acceptable industry standards that cover the materials and design for piping and piping components. Some of the common organizations that issue industry standards are as follows: •

American National Standards Institute (ANSI).

•

American Society of Mechanical Engineers (ASME).

•

American Petroleum Institute (API).

•

American Society for Testing and Materials (ASTM).


58



•

American Welding Society (AWS).

•

American Water Works Association (AWWA).

•

Manufacturers Standardization Society of the Valve and Fittings Industry (MSS).

•

National Association of Corrosion Engineers (NACE).

The ASME/ANSI B31 piping codes contain tables that list acceptable industry standards for pipe components as follows: •

ASME/ANSI B31.3 - Table 326.1, Component Standards (for metallic components). Table A326.1, Component Standards (for nonmetallic components).

•

ASME/ANSI B31.4 - Table 423.1, Material Standards and Table 426.1, Dimensional Standards.

•

ASME/ANSI B31.8 - Appendix B.

To assist in identifying applicable Industry Standards, lists of these are provided in Addendum B. Material Designation by Industry Standard Once the basic material chemistry is selected, the specific material standards designations for the pipe, fittings, flanges, valves, and bolting must be determined. The material standard designation will usually include an ASTM, API, or BS material designation and a material grade. A list A few useful industry references that contain materials designations versus chemistry are as follows: •

Appendix A (Allowable Stress Tables) in ASME/ANSI B31.3.

•

Table 1A, "List of Materials Specifications" in ASME/ANSI B16.5.

•

Table 1, "List of Materials Specifications" in ASME/ANSI B16.34.

Addendum B-2 is a summary table that gives material chemistry versus product forms for some of the metallic materials that are used by Saudi Aramco. If the basic material and product form


59



have both been determined, this table can be used to find the applicable material specification. ASTM and API materials standards cover most of the metallic pipe that is used by Saudi Aramco. The most often used metallic pipe materials include the following designations: •

API 5L, Gr. B.

•

ASTM A333, seamless, Gr. 6 or Gr. 7.

•

ASTM A671, Gr. CC65 or Gr. CF65, Class 22, or Gr. S2.

The major material designation for transportation line pipe used by Saudi Aramco is API 5L. Acceptable grades are Gr. B and Gr. X-42 or higher. The numerical value in the "X-Grades" of the API 5L specification indicated the yield strength of the specific grade. For example, X-42 has a 42,000 psi Specified Minimum Yield Strength, X-52 has a 52,000 psi Specified Minimum Yield Strength, etc. The line pipe may be manufactured through the use of either a seamless or a welded process. For some of the more exotic or proprietary materials, it is usually sufficient to specify the alloy type and the piping component, such as "Hastelloy C-276 Seamless Pipe." However, it is important to realize that alloy pipe and non-metallic pipe systems may not be designed using the customary factors for carbon steel pipe. Examples of such materials are: •

Hastelloy B-2.

•

Hastelloy C-22.

•

Hastelloy C-276.

•

Monel 400.

•

Alloy 20.

•

Alloy 600.

•

254 SMO Stainless Steel.

Nonmetallic pipe for utility piping within Saudi Aramco usually consists of either Poly-Vinyl Chloride (PVC) or Reinforced


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Material Selection for LowTemperature Service The SAMSS for low-temperature valves, 04-SAMSS-003, allows the following component materials to be used without additional impact testing: •

Materials manufactured of austenitic stainless steel or copper-, nickel-, and aluminum-based alloys.

•

Materials that comply with one of the following specifications, or those with superior impact properties: - Castings: ASTM A352, Gr. LC2. - Forging: ASTM A350, Gr. LF3. - Pipe: ASTM A333, Gr. 3. - Plate: ASTM A203, Gr. B, D, or E. - Bolts: ASTM A320, Gr. L7. -Nuts: ASTM A194, Gr. 4

•

•Materials manufactured to fine-grain practice and normalized for use in services with a minimum design temperature of -12.2°C (10°F) or higher.

04-SAMSS-003 prohibits the use of NBR and other nitrile rubbers. The specification also requires that stem packing be PTFE-lubricated inhibitor-impregnated braided-asbestos packing, or a specified graphite-type packing system. Gaskets for flanges in low-temperature service shall be spiralwound stainless steel non-asbestos-filled, such as Flexitallic Type CG. Bolting shall be ASTM A193, Gr. B7 or B7M with ASTM A194, Gr. 2HM nuts, or A320, Gr. 7 with A194, Gr. 4 or 7 nuts (depending on the specified temperatures). See SAES-L009 for details on gasket and bolting requirements. In addition to giving the material standards designation, the SAMSS's that cover materials for low-temperature service presents the detailed impact test requirements and acceptance criteria for the components.


61



Material Designation for Components Butt-Welded Fittings — ASTM A234, Gr. WPB. The requirements of 02-SAMSS-005 must also be met by the fittings for transportation piping. Flanges and Other Forged Components Used in Transportation Piping — Flanges for transportation piping systems are also selected in accordance with SAES-L-009 and 02-SAMSS-011 requirements. Flange material is selected to be of comparable strength to that of the higher strength steels that are typically used in transportation pipeline systems. Refer to SAES-L-009 and 02-SAMSS-011 for specific requirements. Bolting for Transportation Piping — ASTM A193, Gr. B7 stud bolts with ASTM A194, Gr. 2H nuts should be used. Sour, Wet Service or Services Where the Bolting Will Be Deprived of Atmospheric Exposure — Gr. B7M stud bolts and Gr. 2HM nuts should be used. Gaskets — Type 316 stainless steel, spiral wound, and nonasbestos-filled gaskets are typically used. Flanges, gaskets, and bolting materials must meet the requirements of SAES-L009. Material Selection for Lined, Coated, and Nonmetallic Piping In many instances, it is necessary to use internal linings or external coatings on metallic pipe. Some Saudi Aramco water piping systems use internal cement lining for protection from corrosion. Submarine transportation piping must be coated externally with cement to provide additional mass to compensate for buoyancy. Transportation line pipe must be externally coated with fusion-bonded epoxy (FBE) for corrosion protection.


62



Piping in some services may be made of nonmetallic materials. Examples of such nonmetallic piping systems are as follows: •

Reinforced thermosetting resin (RTR) piping for use in unpressurized sewers.

•

RTR piping used for pressure services.

•

PVC, CPVC, and RTRP piping for use in acidic or caustic services.

In most cases, the materials selection for linings and coatings will be determined in an applicable SAMSS. Nonmetallic pipe material selection will be determined using SAES-L-060 and applicable SAMSS's. SAES-L-005 Piping Specification It should be clear from the previous discussions that a piping system will consist of several different types of components (such as the pipe, valves, flanges, and fittings). Selection of the basic material chemistry that is required for these components are relatively straightforward as previously discussed. However, the specific material standards and other engineering requirements that each of these components are to meet must also be specified in order to correctly design, fabricate, and erect the system. These additional requirements come from a variety of industries and Saudi Aramco documents. In many cases, there will also be more than one technically acceptable option from which to choose. The final selection will also include considerations such as cost, availability, and the desire to standardize. Standardization is desirable in order to simplify future field maintenance and repair activities, to reduce the likelihood of incorrect material being used in the field, and to minimize the number of different types of items that must be stored in Saudi Aramco warehouses. It is possible to go directly to each industry and Saudi Aramco document every time that it is necessary to determine the detailed requirements for a specific component in a particular situation, but this approach is neither practical nor economical. Therefore, standard "piping specifications" are developed for specific projects or locations. A piping specification will typically


63



specify the following items for each particular fluid service and set of design conditions: •

Pipe: Material standard and required wall thickness.

•

Fittings: Type, design standard, and material specification.

•

Valves: Type, design standard, and material specification.

•

Flanges: Type, design standard, type of face, material specification.

•

Gaskets: Type, design standard, and material specification.

•

Bolting: Material specification.

•

Any special fabrication and testing requirements that are associated with the particular service application.

The requirements that are specified in a piping specification are selected to meet all applicable industry and Owner Company requirements for a specific fluid service and set of design conditions. The overall piping specification for a project or location will contain many individual-piping specifications. Each individual piping specification will be for only one general material chemistry; and may include more than one service fluid (as long as each fluid have the same technical requirements); will encompass an appropriate range of design temperature and design pressure conditions; and will be valid for one specified corrosion allowance. SAES-L-005, Piping Material Specification, is almost a complete document of all needed piping system to be used for Saudi Aramco facilities. It covers general piping system, such as transportation piping, process piping systems and utilities piping system. Addendum C-3 is an extract from this document explaining the line designation method followed for Saudi Aramco piping. Also, extracts of typical line classes are in Addendum C-4 to C-6.


64



SUMMARY MEX 101.02 discussed how to select material for pipe and piping components. This includes addressing the factors that influence material selection (such as material strength and toughness), pipe manufacturing processes and their relative qualities, and the applicable industry and Saudi Aramco standards. The selection process requires the engineer to determine material chemistry for pipe and piping components for particular services. There are special requirements specified in Saudi Aramco standards for low-temperature services, coated, and nonmetallic piping. The module concluded with a discussion of general piping specifications that include the specific material requirements for all components in a piping system. MEX 101.03 discusses how to determine pipe thickness.


65



ADDENDUM


66



Section

Page

ADDENDUM ......................................................ERROR! BOOKMARK NOT DEFINED. ADDENDUM A: APPLICABLE SAUDI ARAMCO MATERIAL SPECIFICATIONS FOR PIPE AND PIPING COMPONENTS.................................................................... 699 ADDENDUM B: INDUSTRY STANDARDS APPLICABLE FOR PIPE AND PIPING COMPONENTS....................................................... 744 ADDENDUM C: EXTRACTS FROM SAUDI ARAMCO STANDARDS ............ 822 LINE CLASS DESIGNATOR SYSTEM (SAES-L-005) ..................................... 877 8 BRANCH CONNECTION .............................................................................. 922

LIST OF TABLES

Table A- 1. SAES-L Series Applicable to Piping ........................................................... 69 Table A-1. SAES-L Series Applicable to Piping (Continued)....................................... 70 Table A-2. 01- SAMSS Series Applicable to Piping ..................................................... 71 Table A- 3. 02- SAMSS Series Applicable to Piping Fittings ........................................ 72 Table A- 4. 04- SAMSS Series Applicable to Valves.................................................... 73 Table B- 1. Summary of Mechanical Properties for Materials and Information Sources75 Table B- 2. Material Chemistries for Various Product Forms ....................................... 76 Table B- 3. Industry Standards for Pipe ....................................................................... 77 Table B- 4. Industry Standards for Fittings ................................................................... 78 Table B- 5. Industry Standards for Flanges.................................................................. 79 Table B- 6. Industry Standards for Valves.................................................................... 79 Table B- 7. Standards for Gaskets and Bolting ............................................................ 80 Table B- 8. Industry Standards for Non Metallic Pipe and Piping Components............ 81 Table C-1. Piping Materials Selection -SAES-L-032 .................................................... 83 Table C-1. Piping Materials Selection-SAES-L-032 (Continued).................................. 84 Table C-1. Piping Materials Selection -SAES-L-032 (Continued)................................. 85 Table C-2. Materials Appendix Table I - Service & Application Requirements Valve Body and Trim Materials ........................................................................................ 86


67



Table C-3. Line Class 3CS1P1 .................................................................................... 93 Table C-3. Line Class 3CS1P1 (Continued)................................................................ 94 Table C-4. Line Class 9CJ9P ....................................................................................... 95 Table C-4. Line Class 9CJ9P (Continued) .................................................................. 96 Table C-5. Line Class 12PU0U .................................................................................... 97


68



ADDENDUM A: APPLICABLE SAUDI ARAMCO MATERIAL SPECIFICATIONS FOR PIPE AND PIPING COMPONENTS Table A- 1. SAES-L Series Applicable to Piping Standard

Title

Scope

L-005

Limitations on Piping Components

Covers the selection of compatible pipe material items that are used together in a specific system or service and that are listed in a Piping Specification under a code number.

L-006

Metallic Pipe Selection

Covers limitations on the selection of metallic pipe and tubing for pressure services in plant piping and transportation piping.

L-007

Selection of Metallic Pipe Fittings

Covers limitations on the selection of metallic pipe fittings for pressure services in plant piping and transportation piping.

L-008

Selection of Valves

Covers limitations on the selection of all valves that are normally classified under Saudi Aramco Materials System Class 04. This standard contains tables of applicable materials for valves and valve components. It also contains a section on materials limitations.

L-009

Metallic Flanges, Gaskets, and Bolts

Covers limitations on the selection of metallic pipe flanges, gaskets, and bolting for pressure services in plant piping and transportation piping. This standard references ASTM material standards for specific applications.

L-010

Limitations on Piping Joints

Covers limitations on the selection of piping joints.


69



Table A-1. SAES-L Series Applicable to Piping (Continued) Standard

Title

Scope

L-030

Material for LowTemperature Service

Covers toughness requirements for carbon steels that are used in refrigerated fluid service at a minimum design temperature that is within the range -18°C to 45°C (0°F to -50°F). These requirements, which are more restrictive than the requirements in ASME/ANSI B31.3, supplement that standard.

L-031

Material for LowTemperature Service

Covers toughness requirements for carbon steels that are used in refrigerated fluid service at a minimum design temperature that is within the range -18°C to 45°C (0°F to -50°F). These requirements, which are more restrictive than the requirements in ASME/ANSI B31.3, supplement that standard.

L-032

Material Selection for Piping Systems

Specifies, based on the fluid to be transported, the basic pipe material chemistry for piping systems. Contains a table that lists service fluid (environment), concentration of the fluid transported, service temperature, and whether air is present.

L-060

Nonmetallic Piping

Covers requirements and limitations for the design, installation, and testing of nonmetallic piping, except for plumbing.

L-061

Technically Acceptable RTR Piping

Lists specific RTR pipe and fittings, in accordance with 01-SAMSS-029 or 01-SAMSS-034 that have undergone and passed an evaluation by Saudi Aramco and are acceptable for use in Saudi Aramco installations.


70



Table A-2. 01- SAMSS Series Applicable to Piping Standard

Title

Scope

005

Pipe, CementLined, Shop Applied

Provides references, including material specifications, covering the manufacture, inspection, and testing of cement-lined pipe.

010

Fabricated Carbon Steel Piping

Covers applicable material standards and the minimum requirements for the fabrication of carbon steel pipe spools.

016

Sour, Wet Service Line Pipe

Defines additional requirements that are necessary to obtain welded line pipe that is resistant to Hydrogen Induced Cracking (HIC) in wet, sour environments.

017

Auxiliary Piping for Mechanical Equipment

Defines the minimum requirements that govern the design, fabrication, installation, and inspection of auxiliary piping that is associated with compressors, pumps, fans, turbines, engines, and gears.

035

API Line Pipe

Defines requirements that supplement API specification 5L for beveled end, seamless, or submerged arc-welded (straight seam or spiral seam) carbon steel pipe.

036

LowTemperature Pipe

Covers the requirements for seamless pipe, 25 mm (1 in) nominal size or larger, and for straight seam, submerged arc-welded pipe, 400 mm (16 in.) nominal size and larger, for service with minimum design temperatures between 0°C and -46°C (32°F and 50°F).


71



Table A- 3. 02- SAMSS Series Applicable to Piping Fittings Standard

Title

Scope

001

Piping components for LowTemperature Service

Covers the requirements that apply to piping components for use in refrigerated natural gas liquid (NGL) service with minimum design temperatures between 0°C and -46°C (32°F and -50°F). This specification supplements ASME/ANSI B16.11 and ASME/ANSI B16.14.

005

Butt-Welded Pipe Fittings

Supplements the requirements of ASME/ANSI B16.9 and ASTM A234 Gr. WPB for wrought carbon steel pipe fittings. Also supplements the requirements of MSS SP-75 for high-strength fittings. In addition, it covers fittings suitable for wet, sour service. Does not include cast fittings or corrosion-alloy steel pipe fittings.

010

Flanged Insulating Joints/Spools for Cathodic Protection

Describes the requirements for insulating joints and spools with bolted flanges and any standard pressure rating and pipe diameter.

011

Forged Steel Weld-Neck Flanges for Low- and IntermediateTemperature Service

Covers requirements for forged steel weld-neck flanges for low- and intermediatetemperature services. Included are certain lapped joint and swivel ring assemblies. Also included are special forging such as anchor flanges, long weld-neck flanges, contour-forged (integrally reinforced) and out-size flanges. High-temperature flanges, such as ASTM A182 F5 and F11, and extra-low-temperature flanges, such as ASTM A350 LF3 and LF9, are not covered. This standard supersedes Saudi Aramco Drawing AB036028.


72



Table A- 4. 04- SAMSS Series Applicable to Valves Standard

Title

Scope

011

Additional Requirements for LowTemperature Valves

Contains specific information concerning material requirements for valves in lowtemperature service.

035

General Requirements for Valves

Defines general requirements for valves that are normally classified under Saudi Aramco Materials System (SAMS) Class 04.

048

Valve Inspection and Testing Requirements

Covers the minimum requirements for inspection and testing of metallic and nonmetallic valves that are normally classified under Saudi Aramco Materials System (SAMS) Class 04. Such valves include gate, globe, angle, check, needle, ball, plug, piston, butterfly, choke, diaphragm, etc., that are used for on/off, manual control service or for prevention of reverse flow, as appropriate. Specifically excluded from the scope are: control, safety-relief, relief, surge relief, solenoid, pilot, and other valves that are classified under SAMS Class 34; and wellhead valves that are classified under SAMS Class 45.

049

Inspection and Testing Requirements

Establishes the minimum quality control and testing requirements for API 6A 10,000 psi valves and chokes, 1-13/16 inch and larger, which may be used in sour, wet services downstream of the wellhead and tree assembly. In addition, each of the major valve types used by Saudi Aramco has an SAMSS that lists the necessary industry standards for the particular valve type.


73



ADDENDUM B INDUSTRY STANDARDS APPLICABLE FOR PIPE AND PIPING COMPONENTS


74



Table B- 1. Summary of Mechanical Properties for Materials and Information Sources Mechanical Property Tensile and Yield Strength

Information Source ASME B&PV Code Section II, Parts A&B ASTM Specifications

Use Used to calculate allowable stresses in ASME, Section VIII, Div 1. These are used to calculate wall thickness of pressure vessels.

Percent Elongation and Reduction of Area

ASME B&PV Code Section II, Parts A&B ASTM Specifications Tensile Test Data ASM Metals Handbook

A qualitative measure of ductility. Data are used to compare the relative ductility of several materials. This enables the designer to select the most suitable material for the particular application.

Creep Strength And StressRapture

Material Supplier Mechanical Test Data

Used to establish allowance stresses for elevated term pressure service when the material is in the creep range. A good example is furnace tube designs for high-temperature ethylene pyrolysis and reformer heaters.

ASM Metals Handbook Hardness

ASME B&PV Code Section II, Parts A&B ASTM Specifications ASM Metals and Handbook Hardness Test Data

Toughness

ASME B&PV Code Section II, Parts A&B ASTM Specifications Material Supplier Mechanical Test Data ASM Metals Handbook Impact Test Data


Used to check the effectiveness of PWHT Materials with high hardness usually exhibit good erosion resistance. Low hardness values generally indicative that the material has good ductility. Hardness data can be used to estimate a material’s approximate tensile strength. Refer to ASTM A370. Used to ensure that materials meet the requirements of NACE MR-01-75 when in sour service. Materials that exhibit superior toughness, such as normalized carbon steel, 2 ½ / 3-1/2 / 9% nickel steels and the 300 series austenitic stainless steels are used to fabricate equipment for cryogenic service. Examples of such services include LNG Plants, Gas Liquefaction Units, Ethylene Plants, light olefin units, refrigerated LPG (propane), and liquid nitrogen. Good toughness is needed to prevent brittle fractured of materials in extremely cold services.

75



Table B- 2. Material Chemistries for Various Product Forms Basic Material Pipe Chemistry Carbon Steel API 5L, Gr. B; A106, Gr. B; or A53 Gr. B (seamless)

Forged Fittings A105

API 5L, Gr. B; A333 A350, Gr. (seamless), Gr. 6 or 7; LF 3 A671, Gr. CC 65 or CF 65 C1.22, or Gr. S2 API 5L, Gr. X42 A105 (Pipeline applications only)

C-1/2 Mo

API 5L, Gr. X52 (Pipeline applications only)

—

API 5L, Gr. X60 (Pipeline applications only)

—

A335, Gr. P1

1 1/4 Cr-1/2 Mo

A335, Gr. P11

2 1/4 Cr-1 Mo

A335, Gr. P22

18 Cr-8 Ni (Stainless Steel) 16 Cr-12 Ni-2 Mo (Stainless Steel)

A312, TP304 A312, TP316

A182, Gr. F1 A182, Gr. F11 C1.1 or C1.2 A182, Gr. F22 C1.2 or C1.3 A182, Gr. F304 A182, Gr. F316

Wrought Fittings A234, Gr. WPB

Castings A216, Gr. WCB

A420, Gr. WPL3 or WPL6

A352 Gr. LC2

MSS SP75. See 02SAMSS005. MSS SP75. See 02SAMSS005. MSS SP75. See 02SAMSS005. A234, Gr. WP1 A234, Gr. WP11b C1.1 or WP11 C1.2 A234, Gr. WP22 C1.1

A216 Gr. WCB

A403, Gr. WP304 A403, Gr. WP316

Flanges A350, Gr. LF2; A105N; or A266 Cl 4. See SAES-L-009 & 02-SAMSS-011 A350, Gr. LF2 or A266 Cl 4. See SAES-L-009 & 02-SAMSS-011 A707, Gr. L3 Cl..1 See 02-SAMSS-011.

—

A350, Gr. LF 6 Cl.1. See 02-SAMSS-011.

—

A350, Gr. LF 6 Cl.6. See 02-SAMSS-011.

A217, Gr. WC1 A217, Gr. WC6

A182, Gr. F1

A217, Gr. WC9

A182, Gr. F22 C1.2 or C1.3

A351, Gr. CF 8 A351, Gr. CF 8M

A403, Gr. WP304 A403, Gr. WP316

A182, Gr. F11 C1.1 or C1.2

Note: In cases where multiple material specifications and/or grades are shown, the final selection will be made during detailed engineering based on specific design requirements, cost, schedule, and standardization considerations.


76



Table B- 3. Industry Standards for Pipe Standard

Title

ASTM A106

Seamless Carbon Steel Pipe for High-Temperature Service.

ASTM A53

Pipe, Steel, Black and HotDipped, Zinc Coated, Welded and Seamless.

API 5L

Specification for Line Pipe.

ASTM A333

Seamless and Welded Steel Pipe for Low-Temperature Service.

ASTM A335

Seamless Ferritic Alloy Steel Pipe for High-Temperature Service.

ASTM A312

Seamless and Welded Austenitic Stainless Steel Pipe.

ASTM D2996

Filament-Wound Fiberglass RTR Pipe.

ASTM D2997

Centrifugally Cast RTR Pipe.

ASTM D3517

Fiberglass RTR Pressure Pipe.

ASTM D3754

Fiberglass RTR Sewer and Industrial Pressure Pipe.


Scope

77



Table B- 4. Industry Standards for Fittings Standard

Title

ASME/ANSI B16.9

Factory-Made Wrought Steel Butt-Welded Fittings.

ASME/ANSI B16.11

Forged Steel Fittings, Socket-Welded and Threaded.

ASME/ANSI B16.12

Cast Iron Threaded Drainage Fittings.

ASTM A74

Cast Iron Soil Pipe and Fittings.

ASTM D2665

Polyvinyl Chloride Plastic Drain, Waste, and Vent Pipe Fittings.

(nonmetallic PVC fittings) ASTM D3311 (nonmetallic PVC fittings) ASTM F439 (nonmetallic PVC fittings)

Scope

Drain, Waste, and Vent (DWV) Plastic Fittings. Socket-Type CPVC Plastic Pipe Fittings, Schedule 80.

DIN 8063


78



Table B- 5. Industry Standards for Flanges Standard

Title

ASME/ANSI B16.1

Cast Iron Pipe Flanges and Flanged Fittings, Class 25, 125, 250, and 800.

ASME/ANSI B16.5

Pipe Flanges and Flanged Fittings.

ASME/ANSI B16.47

Large-Diameter Steel Flanges, NPS 26 through NPS 60.

API 605

Large-Diameter Carbon Steel Flanges.

MSS SP-44

Steel Pipe Line Flanges.

API 6A

Wellhead Equipment.

Scope

Table B- 6. Industry Standards for Valves Standard

Title

ASME/ANSI B16.34

Valves–Flanged, Threaded, and Welding End.

API 599

Steel and Ductile Iron Plug Valves.

API 600

Steel Gate Valves – Flanged and Butt-Welding Ends.

API 602

Compact Steel Gate Valves.

API 606

Compact Steel Gate Valves-Extended Body.

API 608

Metal Ball Valves – Flanged and Butt-Welding Ends.

API 609

Lug- and Wafer-Type Butterfly Valves.


Scope

79



Table B- 7. Standards for Gaskets and Bolting Standard

Title

Scope

ASME/ANSI B16.20

Ring Joint Gaskets and Grooves for Steel Pipe Flanges.

Soft iron gaskets in this standard are used by Saudi Aramco for flanged joints requiring an octagonal ringtype gasket.

ASME/ANSI B16.21

Nonmetallic Flat Gaskets Pipe Flanges.

Gaskets in this standard are used by Saudi Aramco for non-hazardous services where sheet gaskets are acceptable.

API 601

Metallic Gaskets for Piping, Double-Jacketed Corrugated and Spiral Wound.

Gaskets in this standard are used for flanged joints in most Saudi Aramco services.

API 6A Type RX

Gaskets for flanges per API 6A.

ASTM D1418

Gasket materials for flanges in acid and other corrosive services.

ASTM A193

Stud Bolts with A194 Nuts.

Used for most services.

ASTM A320

Stud Bolts.

Used for low-temperature services.

ASTM A307

Machine Bolts.

Used for flat-faced cast iron or nonmetallic flanges in non-corrosive service.


80



Table B- 8. Industry Standards for Non Metallic Pipe and Piping Components Standard

Title

ASTM D1785

PVC Plastic Pipe, Sch 40, 80 and 120.

ASTM D2996

Filament-Wound Fiberglass RTR Pipe

ASTM D2997

Centrifugally Cast RTR Pipe

ASTM D3517

Fiberglass RTR Pressure Pipe

ASTM D3754

Fiberglass RTR Sewer and Industrial Pressure Pipe

ASTM D2665

Polyvinyl Chloride Plastic Drain, Waste, and Vent Pipe Fittings.

(PVC fittings) ASTM D3311 PVC fittings) ASTM F439 (PVC fittings)

Scope

Drain, Waste, and Vent (DWV) Plastic Fittings. Socket-Type CPVC Plastic Pipe Fittings, Schedule 80.

DIN 8063


81



ADDENDUM C EXTRACTS FROM SAUDI ARAMCO STANDARDS


82



Table C-1. Piping Materials Selection -SAES-L-032 Environment

Conc. %

Temp. (Deg. C)

Air Present

Velocity (M/S) #

Basic Material

Remarks

Freons

100

0 - 70

N/A

0-3

Carbon steel

See SAES-L-030

Hydraulic Oil

100

-

N/A

0-4

Type 304 or 304L S/S 316L S/S

Type 316L S/S or Monel 400 offshore. See 01-SAMSS-017.

Hydrocarbons Sweet & Sour

100

0 - 280

No

Para. 5

Carbon steel

See para. 4.4 for erosion resistance

100

-

N/A

Para. 5

Type 316L S/S

100

280 - 340

No

Para. 5

5 Cr-1/2 Mo

-

-

No

Para. 5

Per Nelson Chart

See API Publication 941.

Hydrogen

100

-

No

Para. 5

Per Nelson Chart

See API Publication 941

Hydrogen Sulfide, dry

100

0 - 260

No

Para. 5

Carbon steel

See para. 4.4

Hydrogen Sulfide, wet

100

0 - 260

No

Para. 5

Carbon steel Type 316L S/S

Use 316L for high velocity and erosion resistance

5

0 - 49

N/A

0 - 2.4

CPVC

5

0 - 49

N/A

0 - 2.4

RTRP

5

0 - 49

N/A

0-4

Hastelloy C-276

100

Above 0

No

0-4

Carbon steel

See SAES-L-030

100

-

N/A

0-6

Type 304/304L

See 01-SAMSS-017

100

-

N/A

0-6

Type 316/316L

50

15 - 49

N/A

0 - 1.5

Carbon steel

50

50 - 80

N/A

0 - 1.5

Carbon steel

50

50 - 150

N/A

0-4

20

0 - 50

N/A

0 - 1.5

Carbon steel

7

0 - 75

N/A

0 - 1.5

Carbon steel

7

76 - 100

N/A

0 - 1.5

Carbon steel

Hydrocarbon gas plus hydrogen

Hypochlorite, (sodium or calcium)

LPG, NGL Lube oil and seal oil Sodium hydroxide

See SAES-L-060

Para. 4.3

Alloy 600

Para. 4.3

# Maximum (also see para. 5)


83



Table C-1. Piping Materials Selection-SAES-L-032 (Continued) Conc. %

Temp. (Deg. C)

Air Present

Velocity (M/S) #

Freons

100

0 - 70

N/A

0-3

Carbon steel

See SAES-L-030

Hydraulic Oil

100

-

N/A

0-4

Type 304 or 304L S/S 316L S/S

Type 316L S/S or Monel 400 offshore. See 01-SAMSS-017.

Hydrocarbons Sweet & Sour

100

0 - 280

No

Para. 5

Carbon steel

See para. 4.4 for erosion resistance

100

-

N/A

Para. 5

Type 316L S/S

100

280 - 340

No

Para. 5

5 Cr-1/2 Mo

-

-

No

Para. 5

Per Nelson Chart

See API Publication 941.

Hydrogen

100

-

No

Para. 5

Per Nelson Chart

See API Publication 941

Hydrogen Sulfide, dry

100

0 - 260

No

Para. 5

Carbon steel

See para. 4.4

Hydrogen Sulfide, wet

100

0 - 260

No

Para. 5

Carbon steel Type 316L S/S

Use 316L for high velocity and erosion resistance

5

0 - 49

N/A

0 - 2.4

CPVC

5

0 - 49

N/A

0 - 2.4

RTRP

5

0 - 49

N/A

0-4

Hastelloy C-276

100

Above 0

No

0-4

Carbon steel

See SAES-L-030

100

-

N/A

0-6

Type 304/304L

See 01-SAMSS-017

100

-

N/A

0-6

Type 316/316L

50

15 - 49

N/A

0 - 1.5

Carbon steel

50

50 - 80

N/A

0 - 1.5

Carbon steel

50

50 - 150

N/A

0-4

20

0 - 50

N/A

0 - 1.5

Carbon steel

7

0 - 75

N/A

0 - 1.5

Carbon steel

7

76 - 100

N/A

0 - 1.5

Carbon steel

Environment

Hydrocarbon gas plus hydrogen

Hypochlorite, (sodium or calcium)

LPG, NGL Lube oil and seal oil Sodium hydroxide

Basic Material

Remarks

See SAES-L-060

Para. 4.3

Alloy 600

Para. 4.3



84



Table C-1. Piping Materials Selection -SAES-L-032 (Continued) Temp. (Deg. C)

Air Present

Velocity (M/S) #

100

100 - 400

No

Para. 5

100

400 - 480

No

Para. 5

1-1/4 Cr 1/2 Mo Alloy steel

100

480 - 560

No

Para. 5

2-1/4 Cr 1 Mo Alloy steel

-

-

No

0 - 2.25

Carbon steel

-

-

N/A

0-4

Type 304L S/S

CO2 contaminated

100

MP - 150

N/A

0 - 2.25

Carbon steel

Keep dry, moisture causes corrosion. MP denotes melting point

100

MP - 295

N/A

0-4

Type 316L S/S

Water, boiler feed

-

1 - 200

No

0 - 2.25

Carbon steel

Water, cooling (inhibited)

-

1 - 99

N/A

0 - 2.25

Carbon steel

-

1 - 99

N/A

0 - 2.25

Galvanized steel

-

Above 0

No

0 - 2.25

Steel

-

Above 0

No

0 - 2.25

Galvanized steel

-

1 - 49

N/A

0 - 2.4

PVC

-

1 - 49

N/A

0 - 2.4

PVC

-

1 - 71

N/A

0 - 2.4

CPVC

-

1 - 200

N/A

0-4

Type 304 S/S

-

Ambient

N/A

0-3

Steel, cement or FBE lined

See para. 5.3 and SAES-H-002, APCS-103/102

-

Ambient

N/A

0 - 2.4

RTRP

See SAES-L-060

-

Ambient

N/A

Table 2

90-10 Copper Nickel

Alloy C70600

-

Ambient

N/A

0 - 10

254 SMO S/S

Weld with Inconel 625 electrode or filler wire

Environment Steam

Steam condensate

Sulfur, molten

Water. chilled

Water, demineralized or distilled

Water, fire control (sea)

Conc. %

Basic Material

Remarks

Carbon steel

Inhibited against corrosion of steel



85



Table C-2. Materials Appendix Table I - Service & Application Requirements Valve Body and Trim Materials Environment

Conditions Conc.(%) Temp.(C)

Valve Materials Body Trim

Remarks

Acid, Hydrochloric

LT 37

5 - 50

PVC B-2

PVC B-2

No ferric ions or other oxidants for B-2

Acid, Hydrofluoric non-oxidizing

1 - 70 GT 65

5 - 50 5 - 40

M400 PTFE

C-276 PTFE

No glass or glass reinforced plastics; no titanium, zirconium or tantalum

Acid, Hydrofluoric (aerated or oxidizing)

All conc.

to 50

20

20

Acid, Nitric

1 - 70 70 - 99

5 - 50 30 max.

304L (6) 304L

304L 304L

304L is preferred to 316L for nitric acid

Acid, Phosphoric

1 - 85

5 - 50

316 G-3(X)

316L G-3(X)

Applies to chloride or fluoride free grades of phosphoric acid only

Acid, Sulfuric(8) or Sulfurous

90 -100+ 1 -103 to 60 1 - 100

to 50 to 65 to 65 100

316 20 CPVC C-276

316L 20 CPVC C-276

ADIP (AminoDiisopropanol)

20 - 30

5 - 150

CS

316

Air or Nitrogen gas

N/A

0 - 400

CS BR

410 BR

Ammonia, Anhydrous (10)

100

0 - 50

CS

410

Carbon Dioxide dry wet

100 LT 100

0 - 150 5 - 90

CS 316

410 316

Chlorine, dry (12)

100

0 - 70

wet (13)

LT 100

0 - 70

CS M400 PVC C-276

M400 M400 PVC C-276

PVC CPVC C-276

PVC CPVC C-276

Chlorine/Water

1-5

to 50 50 - 80 to 80

No copper alloys allowed

No copper alloys allowed

For castings, Hastelloy C-4 is preferred to C-276

For castings, Hastelloy C-4 is preferred to C-276

(Refer to General and Specific Notes at the end of Table 1)


86



LINE CLASS DESIGNATOR SYSTEM (SAES-L-005) The following system establishes procedures used for identifying new line classes. Commentary Notes:

7.1

1.

The system is based on Process Industry Practices (PIP) to provide a uniform standard consistent with industry practices and specific Saudi Aramco requirements.

2.

Line designations used on existing piping in ex-SAMAREC refineries in Jeddah, Riyadh and Yanbu, and Rabigh Refinery may be in accordance with the original specifications.

Field Definitions and Examples The base piping line class designator system consists of four alpha-numeric fields containing one or two characters each. Each field describes various features of the piping line class. Exceptions, modification, or additions may be made to the base specification, by adding a numeric character after the fourth field to indicate the changes made. Refer to paragraph 7.1.6.

7.1.1 First Field The first field defines the pressure rating and consists of one or two numeric characters. Refer to paragraph 7.2.1. 7.1.2 Second Field The second field defines the pipe material and consists of two alpha characters. Refer to paragraph 7.2.2. 7.1.3 Third Field The third field defines the corrosion or erosion allowance and consists of one numeric character. Refer to paragraph 7.2.3. 7.1.4 Fourth Field The fourth field defines the service and consists of one alpha character. Refer to paragraph 7.2.4.


87



7.1.5 An example of a complete piping line class designator is "3CS1P". This designator specifies an ASME pressure class 300, carbon steel piping system with 1.6 mm corrosion allowance designed for general process service with no changes to the base piping line class material specification. 7.1.6 Modification Suffix A base individual line class material specification may have modifications/additions by adding a numeric character to the base line class designator. Example: line class 1CS1P1 is based on 1CS9P. The modification in this case is 1CS1P1 designed to B31.4 and ERW and X65 pipes permitted. A base individual line class can have more than one modification/addition, e.g. 6CS1P1, 6CS1P2.

7.2

Field Definition Tables

7.2.1 Pressure Rating Symbol

Nominal Pressure Rating Or Class (ASME B16.5/B16.47 Flange Class)

1 3 4 6 9 15 25

150 300 400 600 900 1500 2500 (ASME B16.1 Cast Iron Flange Class)

12 13

125 250 (Specific Rating Designations)

80 85 90 95

Non-pressure Pressure Class 75/150 RF Class 3000, API 6A Class 10000, API 6A

7.2.2 Line Material Symbol CA CB CC CS


Material Impact Tested Carbon Steel Killed Carbon Steel Low Carbon Steel Carbon Steel

88


Piping, Pipelines & Valves Material Selection CG CJ CK CL CM BC BD DC FE LC LE LP NM NR NT PU PV SC SD SJ SX

Galvanized Carbon Steel 1-1/4 Cr-1/2 Mo Alloy Steel 2-1/4 Cr-1 Mo Alloy Steel 5 Cr-1/2 Mo Alloy Steel 9 Cr-1 Mo Alloy Steel Copper Tubing 90-10 Cu-Ni Cast Iron, Grey Glass Fiber Reinforced Epoxy Cement-lined Carbon Steel Epoxy-lined Carbon Steel Polypropylene-lined Carbon Steel Monel 400 Incoloy 800 Carpenter 20 (Alloy 20) CPVC(Chlorinated PVC) PVC(polyvinyl Chloride) 304H Stainless Steel Type 316/316L Stainless Steel 321 Stainless Steel Duplex Stainless Steel

7.2.3 Corrosion Allowance Symbol 0 1 2 3 4 9

Corrosion Allowance Zero corrosion allowance 1.6 mm 3.2 mm 4.8 mm 6.4 mm Corrosion allowance as noted. Refer to SAESL-033 for specific corrosion protection requirements.

7.2.4 Service Symbol A C D H P Q T U W Y


Service Acid Caustic Drain/Sewer Hydrogen Process (General Hydrocarbon) Chlorinating Gas (Owner designator) Wellhead Piping (Owner designator) Utility Water (Owner designator) Chlorine Gas (Owner designator)

89



7.2.5 Saudi Aramco Service Codes Saudi Aramco service codes listed below shall be included in conjunction with the line class designators on P&ID's and other drawings. Example: 6"-FG-123-1CS9P is a 6-inch fuel gas line number 123 and material specification 1CS9P. Code

Service

Code

Service

A AH AS BBD BD BFW BS C CA CAS CAT CS CW CWR CWS

Air Acid Hydrocarbon Acid Sewer Boiler Blow down Blow down Boiler Feed Water Bio-Sludge Chemical Caustic Caustic Sewer Catalyst Chemical Sewer Chilled Water Cooling Water Return Cooling Water Supply

MO N NG OS OW OWS P PA PE PG PO PT PW R RL

Mist Oil Nitrogen Natural Gas Oily Sludge Oily Water Oily Water Sewer Oil & Oil Products Process Air Pond Effluent Purge Gas Pump Out Pump Trims Process Water Refrigerants Relief Line

Code

Service

Code

Service

DGA DFW DMW DSW DT DW E EIA FG FGH FGL FLO FO FW GG H HCL HO HSG

Diglycolamine Deaerator Feed Water Demineralized Water Distilled Water Duct Trims Drinking Water Exhaust Steam Emergency Instrument Air Fuel Gas High Pressure Fuel Gas Low Pressure Fuel Gas Flushing Oil Fuel Oil Fire Water Gart Gas Hydrogen Hydrochloric Acid Hydraulic Oil Hydrogen Sulfide Gas

RLC RLW RW S SA SC SCA SF SO SOW SPO SR SW SWS TPW TW UA UW VG

Cold Relief Line Warm Relief Line Raw Water Steam Sulfuric Acid Steam Condensate Spent Caustic Sulfur Seal Oil Sour Water Slop Oil Sewer (Storm) Salt Water Sanitary Sewer Tempered Water Treated Water Utility Air Utility Water Vent Gas


90



IA LO ME 600C 150C 60C 15C 600S 150S 60S 15S


Instrument Air Lube Oil Methanol 600 psig H.P. Condensate 150 psig M.P. Condensate 60 psig L.P. Condensate 15 psig L.P. Condensate 600 psig H.P. Steam 150 psig M.P Steam 60 psig L.P. Steam 15 psig L.P. Stea

VT W WW

Vessel Trim Water Waste Water

91



8 BRANCH CONNECTION Branch connections for new construction of metallic piping shall be made in accordance with the following table. For field modifications, the branch connections as shown on SASD AB-036719 with proper reinforcement are acceptable.

Branch Connection

B R A N C H

S I Z E

60 56 48 42 40 36 30 24 20 18 16 14 12 10 8 6 4 3 2 1-1/2 1 3/4 1/2 T

T E E E E E E P P P P P W W W W W W W S S S S

T E E E E E P P P P P W W W W W W W S S S S

T E E E E P P P P P W W W W W W W S S S S

T E E E E P P P P W W W W W W W S S S S

T E E E P P P P W W W W W W W S S S S

T E E E P P P W W W W W W W S S S S

T E E E E P W W W W W W W S S S S

T E E E E W W W W W W W S S S S

T E E E W W W W W W W S S S S

T E E W W W W W W W S S S S

T E E W W W W W W S S S S

T E E W W W W W S S S S

T E E W W W W S S S S

T E W W W W S S S S

60 56 48 42 40 36 30 24 20 18 16 14 12 10 8 HEADER SIZE

T E W W W S S S S

6

T E W W S S S S

4

T E W S S S S

3

T E S S S S

2

T E T S E T S E E T S E E E

1-1/2 1 3/4 1/2

LEGEND P

Branch weld with reinforcing pad, (pad thickness equals header pipe thickness, pad width equals 1/2 branch pipe OD)

S

Sockolet or Threadolet or Welding boss per SASD's AE-036175 and AE-036643

W

Weldolet or branch weld with reinforcing pad

E

Reducing tee

T

Equal Tee


92



Table C-3. Line Class 3CS1P1 Line Class: 3CS1P1 Service: Refer to Table 1, Part I Rating Class: 300 RF B16.5 Temperature Limit: -18 to 121° C (2) Corrosion Allowance: 1.6 mm (1) Item PIPE

Size

Basic Material: Carbon Steel Code: B31.4 Stress Relief: Per Code Examination: Per Code Buttweld Construction: B16.25 Rating Schedule

2" and under

Sch 80

3" to 6" 8" and above

Sch 40 Calculate 6.4 mm min.

1½" and under

Class 3000

2" and above 2" and under

Sch 80

2" and under 1½" and under

Class 3000 Class 3000

2" and above 1½" and under

Class 300

2" and above

Class 300

Type

Specification

Notes

Seamless or Welded

A106 Gr. B or API 5L Gr. B, or X60

(1) (2) (3)

Socketweld/ Threaded

A105N, B16.11

(4)

Buttweld Seamless

A234 Gr. WPB, B16.9 A106 Gr. B or API 5L Gr. B A105N, MSS SP83 A105N, B16.11

(5)

FITTINGS El's Tees, Reducers, Caps, Couplings etc. Nipples and Swages Unions Sockolets/ Threadolets Weldolets FLANGES

Socketweld/ Threaded Buttweld Socketweld RF Weldneck RF

A105N, B16.9 A105N, B16.5

BOLTING

A193 B7 stud bolts, semi-finished, heavy pattern with A194 Gr. 2H heavy hex nuts.

GASKETS

Spiral-wound, 316 SS windings, flexible graphite filled with carbon steel outer ring, per B16.20. 1½" and under Class 800 Socketweld/ A105N body, BB, OS&Y, Threaded graphite packing, API 602, Trim No. 8 2" and above Class 300 RF Flanged A216-WCB body Wedge type: BB, OS&Y, graphite packing API 600, Trim No. 8 Thru-cond.: API 6D, Trim ENP or SS 410 1½" and under Class 800 Socketweld/ A105N body, BB, Threaded OS&Y, graphite packing, Trim No. 8 2" and above Class 300 RF Flanged A216-WCB body, BB, OS&Y, graphite packing, Trim No. 8

GATE VALVES

GLOBE VALVES


(4)

(5) (8)

(6) (7)

93



Table C-3. Line Class 3CS1P1 (Continued) Item CHECK VALVES BALL VALVES

PLUG VALVES

BUTTERFLY VALVES

Size

Rating Schedule

Type

1½" and under

Class 800

Socketweld/ Threaded RF Flanged

2" and above

Class 300

1½" and under

Class 300


2" to 4"

Class 300

RF Flanged

6" and above

Class 300

RF Flanged

1½" and under

Class 300


2" and above

Class 300

RF Flanged

4" and above

Class 300

Lugged or RF Flanged

Specification A105N body, BC, Trim No. 1 A216-WCB body, BC, Trim 1 A105N body, floating ball, RTFE seats, Trim No. 10 A216-WCB body, floating ball, RTFE seats, fire safe, API 6D, Trim No. 10 A216-WCB body, trunnion mounted, fire safe, API 6D, Trim ENP or SS 410 A105N body, lubricated, inverted pressure balanced, BC, Trim SS 316 A216-WCB body, lubricated, inverted pressure balanced, API 599, Trim ENP or SS 410 A216-WCB body, high performance, fire-safe, API 609 Cat. B, Trim ENP or SS 316

Notes

(6) (6)

(6) (7)

(7)

(7)

Notes: (1)

The pipe wall thickness specified are based on a design factor of 0.72 and a corrosion allowance of 1.6 mm is included in the pipe and fitting wall thickness. For service conditions that require higher corrosion allowances, the wall thickness are to be increased accordingly. Note, when a small decrease in corrosion allowance would permit the use of the nearest minimum pipe schedule, approval must be obtained from the Consulting Services Department, Saudi Aramco.

(2)

Service temperatures and material grade limits shall be in accordance with B31.3, Table A-1.

(3)

Seamless or double-submerged arc welded pipe required.

(4)

Refer to SAES-L-010 for seal welding requirement of threaded connections.

(5)

Schedule of fittings and weldneck flanges to be same as pipe.

(6)

Where non-metallic seats, seals, liners etc. are used, the manufacturer's pressure/temperature ratings shall limit the service of this class. If seal welding is required, threaded end valves shall have extended bodies to prevent damage due to welding heat.

(7)

Refer to SAES-L-008 and the applicable SAMSS for trim selection.

(8)

Refer to SAES-L-009 for flange material selection.


94



Table C-4. Line Class 9CJ9P Line Class: 9CJ9P Service: Refer To Table 1, Part II Rating Class: 900 RF B16.5 (1) Temperature Limit: 595 Deg C Max.(2) Corrosion Allowance: 1.6 mm (3) Item PIPE

Size 8" and under

Basic Material: 1¼Cr.-½Mo. (2) Code: B31.3 Stress Relief: Per Code Examination: Per Code Buttweld Construction: B16.25 Rating Schedule

Type

Specification

Notes

Calculate Sch 80 min Calculate Sch 40 min

Seamless

A335-Gr. P11

(3)

Seamless or EFW

A335-Gr. P11 or A-691 Gr. 1¼ Cr. Class 32.

(3)

1½" and under

Class 3000


A182 Gr.F11, B16.11

(4)

2" and above ½"-1½"

Buttweld Seamless

A234 Gr. WP11, B16.9 A335-Gr. P11

(5)

Sch 80 min

1½" and under

Class 6000

10" to 24" FITTINGS El's, Tees Reducers, Caps, Couplings, etc. Nipples and Swages Unions Sockolets/ Threadolets Weldolets FLANGES

BOLTING GASKETS

GATE VALVES

GLOBE VALVES

CHECK VALVES

Socketweld/ A182-Gr. F11, B16.11 Threaded 2" and above Buttweld A182-Gr. F11, B16.9 1½" and under Class 1500 Socketweld A182-Gr. F11, B16.5 RJ or RF 2" and above Class 900 Weldneck A182-Gr. F11, B16.5 RJ or RF A193 B7 stud bolts, heavy pattern with A194 2H heavy hex nuts up to 425 deg C. A193 B16 stud bolts, heavy pattern with A194 4 heavy hex nuts up to 595 deg C. For RF: Spiral-wound, 316 SS windings, flexible graphite filled with carbon steel outer rings, per B16.20 up to 425 deg C. Spiral-wound, 321 or 347 SS windings, flexible graphite filled with 316 SS outer rings, per B16.20 up to 595 deg C. For RJ: 5Cr-½Mo Octagonal Ring. 1½" and under Class 1500 Socketweld A182-F11 body, BB, OS&Y, API 602, Trim No.8 2" and above Class 900 RF or RJ A217-WC6 body, BB, Flanged OS&Y, API-600, Trim No.8 1½" and under Class 1500 Socketweld A182-F11 body, BB, OS&Y, Trim No.8 2" and above Class 900 RF or RJ A217-WC6 Body, BB, Flanged OS&Y, Trim No.8 1½" and under Class 1500 Socketweld A182-F11 body, BC, Trim No.1 2" and above Class 900 RF or RJ A217-WC6 Body, BC, Flanged Trim No.1


(6) (4)

(5)

(8)

(7)

95



Table C-4. Line Class 9CJ9P (Continued) Notes: (1)

Use RJ flanges only when required on equipment.

(2)

For hydrogen service, refer to API-941 for temperature limits of material at applicable hydrogen partial pressure.

(3)

A corrosion allowance of 1.6 mm is included in the pipe and fitting wall thicknesses. For service conditions that require higher corrosion allowances, the wall thicknesses are to be increased accordingly. Note. When a small decrease in corrosion allowance would permit the use of the nearest minimum pipe schedule, approval must be obtained from the Consulting Services Department, Saudi Aramco.

(4)

Threaded connections only allowed downstream of vents, drains, hydrotest connections, and instrument take-offs. Threaded O'lets only allowed for thermowell and hydrotest connections.

(5)

Schedule of fittings and weldneck flanges to be same as pipe.

(6)

Use flanges.

(7)

Double-block valves required for vent and drain connections.

(8)

Spiral-wound gaskets for vacuum and catalyst services also require 316 SS inner rings. Limited to 550 °C in hydrogen service.


96



Table C-5. Line Class 12PU0U Line Class: 12PU0U (Formerly 2E3D) Service: Refer to Table 1, Part III Pressure/Temperature Limit: Notes (5) Corrosion Allowance: 0 mm Item

Size

Basic Material: CPVC Design Code: ASME B31.3, Note (1) Examination: ASME B31.3 Joint Construction: Notes (2) (3) Rating Schedule

Type

Specification

PIPE FITTINGS FOR SOLVENT WELD JOINTS

½"- 6"

Sch. 80

CPVC

ASTM F441 CPVC 4120

Bushings Couplings Elbows Tees Pipe Union

½"- 6"

Sch. 80

CPVC

ASTM F439 CPVC 4120, Sch. 80, 0 to 72°C

½"- 3"

Sch. 80

CPVC

ASTM F439 CPVC female socket by male IPS adaptor

Socket Type

¾"- 6"

Flat Face

Threaded type

½"- 2"

GASKETS

3.2 mm

Class 150, Sch. 80 Class 150, Sch. 80 50-60 Shore A durometer

BOLTING

All Sizes

ASTM F439 CPVC, Sch. 80 Class 150 FF ASTM F437 CPVC Class 150 FF Full face elastomeric, 50-60 Shore A durometer ASTM A307 Grade A or B bolts, ASTM A563 Grade A heavy hex nuts ASTM F493 CPVC to PVC or CPVC

Notes (2)

(3)

FLANGES

Flat Face Elastomeric

SOLVENT CEMENT VALVES (All Types)

Use 12LC0U and 12BD0U valves

Ball Valves And Ball Check Valves

½" and above


150 psi

Threaded Socketweld Flanged FF

(2)

(4) (6)

CPVC ASTM D1784 CL. 23447-B body and ball, EPDM seats, double union

97



Table C-5. Line Class 12PU0U (Continued) Notes: (1)

See Saudi Aramco Plumbing Code SAES-S-060 for material usage within buildings. For non-process services, see SAES-S series for applicable design code.

(2)

Threaded pipe shall be derated 50% from the applicable pressure rating. Threaded joints 2 inch and larger shall be seal welded with solvent cement.

(3)

Union adaptors between thermoplastic and metallic pipe have a plastic socket for solvent cementing and a red brass female pipe threaded end.

(4)

Use washers on both ends of the bolts. Corrosion protection is required for below ground use. Consideration shall be given to fluoropolymer coated bolts for buried service. Coated bolts are not stocked. DURABOLT is available from Saudi Conduit Coating Co., P.O. Box 230, Al Khobar.

(5)

Maximum operating pressures appear in the table below. CPVC 4120, formerly Type IV Grade 1 CPVC, now meets cell classification CPVC 23447-B.


98

Material Selection

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