PIPING ELEMENTS
Piping elements is defined as any material required install the piping system.
It includes specifications, material, components, fabrication, inspection and testing.
PIPING ELEMENTS
PIPES
FITTINGS
FLANGES
GASKETS
BOLTING VALVES SPECIALITIES
PIPES
MANUFACTURING PROCESSES
MATERIAL SELECTION
MATERIALS
Classification Based on Manufacturing Pipe
Seamless Seamless pipe
Ferrous pipe materials
Forged pipe
Forged and Bored PIpe
Welded pipe
Ferrous Ferrous pipe materials
Hollow Forged Pipe Hot Rotary Piercing
Furnace Welded Pipe
Pilger Mill Process
Fusion Welded Pipe
Push Ben ch (Cupping) Process
Resistance Welded Pipe
Cast Steel Pipe
Cast Iron Pipe
Centrifugally Cast Pipe
Vertical Pit Process
Cold-Wrought Pipe
Horizontal Process Centrifugal casting in sand moulds Centrifugal Casting in Metal mou lds
Extrusion Process High Frequency Induction Alu mi nium ni um and its it s all oy mat eri als
High Frequency Resistance Horizontal Extrusion Process
Arc Welding Process
Copper and Its alloy materials
Submerged Arc Welding Hot Piercing Process Extrusion Process Cup and Draw Process Tube Rolling Process Nickel and its alloy materials
Extrusion Process Cold Drawing Titanium and its alloy materials
Inert Gas Welding Spiral Welded Pipe
HOT ROTARY PIERCING
PIERCING MILL
PLUG ROLLING MILL
REELING MILL
SIZING MILL
PILGER – MILL PROCESS
PUSH BENCH(CUPPING) PROCESS
EXTRUSION PROCESS
MATERIAL SELECTION CONSIDERATIONS Piping system material selection considerations are discussed below.
A. Strength •Yield and Tensile Strength
•Creep Strength •Fatigue Strength
B. Corrosion Resistance C. Material Fracture Toughness D. Fabricability E. Availability And Cost
A. Strength A material's strength is defined by its yield, tensile, creep, and fatigue strengths. Alloy content, material grain size, and the steel production process are factors that affect material
1.0 Yield and Tensi le Strength A stress-strain diagram that is produced from a standard tensile test (Figure ) illustrates the yield and tensile strengths. As the stress in a material increases, its deformation also increases. The yield strength is the stress that is required to produce permanent deformation in the material (Point A in Figure ). If the stress is further increased, the permanent deformation continues to increase until the material fails. The maximum stress that the material attains is the tensile strength (Point B in Figure ). If a large amount of strain occurs in going from Point A to Point C, the rupture point, the material is said to be ductile. Steel is an example of a ductile material. If the strain in going from Point A to Point C is small, the material is brittle. Gray cast iron is an example of a brittle material.
SC
E
Typical Stress-Strain Diagram for Steel Figure 3.1
2.0 Creep Strength Below about 750°F for a given stress, the strain in most materials remains constant with time. Above this temperature, even with constant stress, the strain in the material will increase with time. This behavior is known as 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.
The temperature at which creep strength begins to be a factor is a function of material chemistry. For alloy materials (i.e., not carbon steel) creep strength becomes a consideration at temperatures higher than 750°F.
3.0 Fatigue Strength The term “fatigue” refers to the situation where a specimen breaks under a load that it has previously withstood for a length of time, or breaks during a load cycle that it has previously withstood several times. The first type of fatigue is called “static,” and the second type is called “cyclic.” One analogy to cyclic fatigue is the bending of a paper clip. The initial bending beyond a certain point causes the paper clip to yield (i.e., permanently deform) but not break. The clip could be bent back and forth several more times and still not break. However after a sufficient number of bending (i.e., load) cycles, the paper clip will break under this repetitive loading. Purely elastic deformation (i.e., without yielding) cannot cause a cyclic fatigue failure.
The fatigue strength of a material under cyclic loading can then be defined as the ability to withstand repetitive loading without failure. The number of cycles to failure of a material decreases as the stress resulting from the applied load increases
B. Corrosion Resistance
Corrosion of materials involves deterioration of the metal by chemical or electrochemical attack. Corrosion resistance is usually the single most important factor that influences pipe material selection. Table below summarizes the typical types of piping system corrosion.
For process plant piping systems in corrosive service, corrosion protection is usually achieved by using alloys that resist corrosion. The most common alloys used for this purpose are chromium and nickel. Low-alloy steels with a chromium content of 1¼% to 9% and stainless steels are used in corrosive environments.
Typical Types of Piping System Corrosion
General or Uniform Corrosion
Characterized by uniform metal loss over entire surface of material. May be combined with erosion if material is exposed to high-velocity fluids, or moving fluids that contain abrasive materials.
Pitting Corrosion
Form of localized metal loss randomly located on material surface. Occurs most often in stagnant areas or areas of low-flow velocity.
Galvanic Corrosion
Concentration Cell Corrosion Graphitic Corrosion
Occurs when two dissimilar metals contact each other in corrosive electrolytic environment. The anodic metal develops deep pits or grooves as a current flows from it to the cathode metal.
Occurs when different concentration of either corrosive fluid or dissolved oxygen contacts areas of same metal. Usually associated with stagnant fluid. Occurs in cast iron exposed to salt water or weak acids. Reduces iron in the cast iron and leaves the graphite in place. Result is extremely soft material with no metal loss.
C. Material Fracture Toughness
One way to characterize the fracture behavior of a material is the amount of energy necessary to initiate and propagate a crack at a given temperature. This is the material's fracture toughness, which decreases as the temperature decreases. Tough materials require a relatively large amount of energy to initiate and propagate a crack. The impact energy required to fracture a material sample at a given temperature can be measured by standard V-notch tests.
Various factors other than temperature affect the fracture toughness of a material. These include the following: . •Chemical composition or alloying elements. . • Heat treatment. . • Grain size.
The major chemical elements that affect a material's fracture toughness are carbon, manganese, nickel, oxygen, sulfur, and molybdenum. High carbon content, or excessive amounts of oxygen, sulfur, or molybdenum, hurts fracture toughness. The addition of manganese or nickel improves fracture toughness.
D. Fabricability A material must be available in the shapes or forms that are required, and it typically must be weldable. In piping systems, some common shapes and forms include the following: . • Seamless pipe. . •Plate that is used for welded pipe. . •Wrought or forged elbows, tees, reducers, and crosses. . •Forged flanges, couplings, and valves. . • Cast valves.
E. Availability and Cost The last factors that affect piping material selection are availability and cost. Where there is more than one technically acceptable material, the final selection must consider what is readily available and what are the relative costs of the acceptable options. For example, the use of carbon steel with a large corrosion allowance could be more expensive than using a low-alloy material with a smaller corrosion allowance.
PIPE FITTINGS A. Fittings, Flanges, and Gaskets 1.0 Pipe Fittings
Fittings are used to make some change in the geometry of a piping system. This change could include: •Modifying the flow direction. •Bringing two or more pipes together. •Altering the pipe diameter. •Terminating a pipe.
PIPETYPESFITTINGS OF PIPE FITTINGS ELBOWS
TEES
45 ELBOW
CAPS
COUPLINGS
EQUAL TEE
UNIONS
SWAGE COUPLINGS
CON.SWAGE
FULL
STUB ENDS
REDUCERS
SPECIAL FITTINGS
LONG STUB ENDS OLETS
90 ELBOW
REDUCING TEE
HALF
ECC.SWAGE
EXPANSION BELLOW
SHORT STUB ENDS STRAINERS WELDOLET
REDUCING SHORT RADIUS
THREDOLET
LONG RADIUS
SOCKOLET FLEXOLET LATROLET ELBOLET SWEEPOLET INSERT WELDOLET NIPPOLET BRAZOLET COUPOLET
END CONNECTION
SOCKET WELD
SCREWED
BUTT WELD
FLANGED
SPIGOT/SOCKET
STEAM TRAPS
ELBOW
REDUCERS
TEES
Pipe Fittings-Standards
ASA B16b1: Cast Iron Pipe Flanges and Flanged Fittings for 800 Psig Hydraulic Pressure
ASA B16b2: Cast Iron Pipe Flanges and Flanged Fittings,25lb
ASA B16.1: Cast Iron Pipe Flanges and Flanged Fittings, Class 125(standard Includes Also Bolt,nut and Gasket Data)
ASA B16.2: Cast Iron Pipe Flanges and Flanged Fittings, Class 250 (Bolt,nut and Gasket Data are also included)
ASA B16.4: Cast Iron Screwed Fittings ASA B 16.12: Cast Iron Screwed Drainage Fittings WW-P-491: Pipe Fittings,cast Iron , Drainage WW-P-501: Pipe Fittings,cast Iron,screwed 125 and 250 Pounds
FLANGES
FLANGES A flange connects a pipe section to a piece of equipment, valve, or another pipe such that relatively simple disassembly is possible. Disassembly may be required for maintenance, inspection, or operational reasons. Flanges are normally used for pipe sizes above NPS 1½.
BASED ON PIPE ATTACHMENT
SLIP – ON SOCKET WELD SCREWED LAP JOINT
WELDING NECK BLIND
INTEGRAL
BASED ON THE FACE OF THE FLANGE FLANGE FACING FLAT FACE RAISED FACE TONGUE AND GROOVE MALE ANE FEMALE RING TYPE JOINT
Flat Face Flanges
Cross section of Flat Face flange
Raised Face Flanges
Cross section of Raised Face flange
Ring Joint Face Flanges
Cross section of Ring Joint Face flange
Male & Female Joint
Cross section of Male & Female Joint
BASED ON PRESSURE-TEMPERATURE RATING
150# 300# 600# 900# 1500# 2500#
FACE FINISH SMOOTH SMOOTH FINISH FINISH SERRATED SERRATED FINISH FINISH
FLANGE MATERIALS ASTM ASTMA A105 105 -- Forged ForgedCarbon Carbonsteel steel ASTM ASTMA A181 181 -- Forged ForgedCarbon Carbonsteel steel for for general general purpose purpose ASTM ASTMA A182 182 -- Forged Forgedalloy alloy steel steel and andstainless stainless steel steel ASTM ASTMA A 350 350 -- Forged Forgedalloy alloy steel steel for for low lowtemperature temperature services services ANSI ANSI B B 16.47/API 16.47/API 605 605––Higher Higher sizes(above sizes(above3”) 3”) IS IS 6392 6392
SELECTION OF FLANGE A flange type is specified by stating the type of attachment and the type of face. The type of attachment defines how the flange is connected to a pipe section or piece of equipment (e.g., welded). The type of flange face or facing defines the geometry of the flange surface that contacts the gasket.
Flange Rating ASME B16.5, Pipe Flanges and Flanged Fittings, provides steel flange dimensional details for standard pipe sizes through NPS 24. Specification of an ASME B16.5 flange involves selection of the correct material and flange "Class."
Flange Rating STEPS INVOLVED IN FLANGE RATING
Refer to ASME B16.5 for material specifications and corresponding Material Group Numbers. –Table 1.1A
After the Material Group has been determined, the next step is to select the appropriate Class. The Class is determined by using pressure/temperature rating tables, the Material Group, design metal temperature, and design pressure.
Flange material specifications listed in Table 1A in ASME B16.5
SAMPLE PROBLEM 1 - DETERMINE FLANGE RATING A new piping system will be installed at an existing plant. It is necessary to determine the ASME class that is required for the flanges.
The following design
information is provided: .
•Pipe Material: 1¼ Cr – ½ Mo.
.
•Design Temperature: 700°F.
.
•Design Pressure: 500 psig.
SOLUTION Determine the Material Group Number for the flanges by referring to ASME Table 1A. Find the 1¼ Cr – ½ Mo material in the Nominal Designation Steel column. The material specification for forged flanges would be A182 Gr. F11, and the corresponding material Group Number is 1.9. Refer to Table 2 for Class 150. Read the allowable design pressure at the intersection of the 700°F design temperature and Material Group 1.9. This is only 110 psig and is not enough for this service. Now check Class 300 and do the same thing. The allowable pressure in this case is 570 psig, which is acceptable. The required flange Class is 300.
FLANGE LEAKAGES
Uneven bolt stress Poor flange alignment Off-center gasket installation Dirty & damaged flange faces
Thermal shock Incorrect gasket size
High vibration
BOLTING
MATERIAL FOR CONSTRUCTION OF BOLTING
DIMENENSINAL STANDRADS FOR BOLTS
MATERIALS ASTM A 307 - Low carbon steel bolting material Alloy steel bolting material for low ASTM A 320 temperature
ASTM A 193 - Alloy steel bolting material for high temperature Alloy steel nut material for high ASTM A 194 temperature service - Threaded steel fasteners IS 1367
STANDARDS ANSI B 18.2.1 ANSI B 18.2.2
BS 916 IS 1367
-
Square & Hex. Head bolts Square & Hex. Nuts Black bolts bolts & nuts Threaded steel fasteners
GASKETS A gasket is a resilient material that is inserted between the flanges and seated against the portion of the flanges called the “face” or “facing”. The gasket provides the seal between the fluid in the pipe and the outside, and thus prevents leakage. Bolts compress the gasket to achieve the seal and hold the flanges together against pressure and other loadings.
GASKETS
1. 1.
2. 2.
3. 3.
SELECTION Compatibility of gasket material with the fluid Ability to withstand pressure and temperature of the system Corrosion of fluids flowing through the flanges
CLASSIFICATIONS Full face Inside bolt circle
Spiral wound metallic Ring type
Metal jacketed
MATERIAL STANDARDS
IS 2712,Gr W/1,W/2,W/3 : For steam alkali general applications
IS 2712 ,Gr A/1
: For acid applications
IS 2712 Gr 0/1, 0/2,0/3
: For oil applications
DIMENSIONAL STANDARDS API 601 API 3381
: Metallic gaskets for refinery piping : Metallic spiral wound gaskets ANSI B 16.20: Metallic gaskets for m pipe flanges
ANSI B 16.21: Non Metallic gaskets for pipe flanges
Ball Ball valves valves
Butterfly Butterfly valves valves
Gate Gate valves valves
ISOLATION VALVES
Plug Plug valves valves
Diaphragm Diaphragm valves valves
Globe Globe valves valves
Needle Needle valves valves
REGULATION VALVES VALVES
Diaphragm Diaphragm valves valves
Butterfly Butterfly valves valves
Non-return valve
Lift Lift check check valve valve
Swing Swing check check valve valve
Safety valve
Special purpose
Float valve
Foot valve
SPECIAL FITTING OLETS E XPANSION BELLOWS
STEAM STRAPS STRAINER
OLETS WELDOLET THREDOLET SOCKOLET INSERT WELDOLET FLEXOLET BRAZOLET NIPPOLET COUPOLET SWEEPOLET ELBOLET & LATROLET
WELDOLET They are economical butt welded branch connections with integral reinforcement
Weldolet, an economical butt-weld branch connection, is designed to minimize stress concentrations and provide integral reinforcement.
Thredolet utilizes the basic Weldolet configuration, provides a threaded outlet branch connection.
Sockolet utilizes the basic Weldolet design configuration and incorporates a socketweld outlet.
Flexolet’s Straight Thru Bore design allows for easy clean up of any base welding penetrating into the I.D. bore by grinding, etc. Flexolet is available in threaded, butt-weld and socket weld fittings.
Latrolet, used for 45° lateral connections, is available butt-weld to meet the specific reinforcement requirements, and 3000# or 6000# classes for socket weld and threaded applications.
Elbolet is used on 90° Long Radius Elbows (can be manufactured for Short Radius Elbows) for thermowell and instrumentation connections. Available butt-weld to meet the specific reinforcement requirements, and 3000# and 6000# classes for socket weld and threaded applications.
Sweepolet is a contoured, integrally reinforced, butt-weld branch connection with a low stress intensification factor for low stresses and long fatigue life. The att achment weld is easily examined by radiography, ultrasound and other standard non-destructive techniques.
Insert Weldolet is another contoured buttweld branch connection used in less critical applications. Like the Sweepolet, the attachment welds are easily examined by radiography, ultrasound and other standard non-destructive techniques.
Nipolet is a one piece fitting for valve take-offs, drains and vents. Manufactured for Extra Strong and Double Extra Strong applications in 3 1/2" to 6 1/2" lengths. Available with male-socket-weld or male threaded outlets.
Brazolet is designed for use with brass or copper tubing. Available with socket or threaded connections.
Coupolet fittings are designed for use in fire protection sprinkler systems and other low pressure piping applications. manufactured with NPT female threads for 300# service
