Page : 1 of 87
KLM Technology Group
Rev: 02
Practical Engineering Guidelines for Processing Plant Solutions
Rev 1 JUNE 2010 Rev 2 JUNE 2011
www.klmtechgroup.com
Author:
KLM Technology Group
STORAGE TANK SELECTION AND SIZING (ENGINEERING DESIGN GUIDELINE)
Rev 1 Karl Kolmetz Rev 2 Aprilia Jaya Checked by:
Karl Kolmetz
TABLE OF CONTENT INTRODUCTION Scope
5
General Design Considerations
6
TYPES OF TANKS Fixed Roof Tanks
7
External floating roof tanks
11
Internal floating roof tanks
15
Domed external floating roof tanks
18
Horizontal tanks
20
Pressure tanks
22
Variable vapor space tanks
23
TANK SEALS AND FITTINGS
25
External and Domed External Floating Roof Rim Seals
25
External and Domed External Floating Roof Deck Fittings
32
Page 2 of 87
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
DEFINITIONS
45
NOMENCLATURE
53
THEORY OF THE DESIGN
55
1. Tank Dimension
55
2. Atmospheric storage tank
59
3. Pressure Storage Tank
63
4. Refrigerated Storage
65
5. Emissions Losses
66
A. Total Losses from Fixed Roof Tanks
66
B. Total Losses from Floating Roof Tanks
69
APPLICATION
75
Example 1: Dimension of tank calculate
75
Example 2: Fixed Roof Tank Emission (Cone Roof and Dome Roof)
78
Example 3: Floating Roof Emission Losses
81
REFEREENCES
84
CALCULATION SPREADSHEET
85
Dimension of Tank Spreadsheet.xls
85
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
Page 3 of 87
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Fixed Roof Tank Emission Losses Spreadsheet.xls
86
Floating Roof Emission Losses Spreadsheet.xls
87
LIST OF TABLE Table 1: Maximum allowable stress value (f)
56
Table 2: Maximum allowable efficiencies for Arc and Gas welded joints
57
Table 3: Dimension of icr, rc, and sf
58
Table 4: Size of innage and outage of tank
61
Table 5: Nozzle service for tank
62
Table 6: Paint Factors for Fixed Roof Tanks
67
Table 7: Rim-seal loss factor
71
Table 8: Average Clingage Factors (Cs)
72
Table 9: Typical Number of Columns as a Function of Tank Diameter
72
Table 10: Deck-Fitting Loss Factors and Typical Number oF Deck Fitting
78
LIST OF FIGURE Figure 1: Fixed Roof Tanks
9
Figure 2: Fixed Roof Tanks 2
10
Figure 3: External Floating Roof Tanks
12
Figure 4: External Floating Roof Tanks 2
13
Figure 5: Typical List of Floating Roof Fittings
14
Figure 6: Internal Floating Roof
17
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
Page 4 of 87
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Figure 7: Dome External Floating Roof
19
Figure 8: Schematics of above-ground horizontal (a) and underground tanks (b)
21
Figure 9: Scheme of Pressure Tank
22
Figure 10: Variable Vapor Space Tanks
24
Figure 11: Vapor mounted primary seals
26
Figure 12: Liquid-mounted and mechanical shoe primary seals
27
Figure 13: Secondary rim seals
29
Figure 14: Access Hatch
32
Figure 15: Gauge float
33
Figure 16: Sample ports
34
Figure 17: Rim vent
35
Figure 18: Deck drains
36
Figure 19: Deck leg
37
Figure 20: Slotted and unslotted guidepoles
38
Figure 21: Vacuum breaker
41
Figure 22: Fixed Roof Support Column
43
Figure 23: Ladder and well
44
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 5 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
INTRODUCTION Scope This design guideline covers the sizing and selection methods of a storage tank system used in the typical process industries. It helps engineers understand the basic design of different types of storage tank systems and increases their knowledge in selection and sizing. The selection section contains the explanation for the suitability of types of tank system used in processing industries, which are based on the environmental regulations, location, and process materials involved. All the important parameters used in this guideline are well explained in the definition section which helps the reader understand the meaning of the parameters and the terms used. The theory section includes sizing theory and formulations for the tanking systems design. In the application section, three cases examples are included by guiding the reader step by step to do tank sizing. In the end of this guideline, example specification data sheets for the tank system are included which is created based on an industrial example. Calculation spreadsheet is included as well and to aid user more understand and to apply the theory for calculations.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 6 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
General Design Considerations Storage vessels containing organic and non organic liquids and vapors can be found in many industries, including; (1) petroleum producing and refining, (2) petrochemical and chemical manufacturing, (3) bulk storage and transfer operations, and (4) other industries consuming or producing liquids and vapors. Liquids and vapors in the petroleum industry, usually called petroleum liquids or vapors, generally are mixtures of hydrocarbons having dissimilar true vapor pressures. Examples would include jet fuel, diesel, gasoline and crude oil. Liquids and vapors in the chemical industry, usually called volatile organic liquids and vapor, are composed of pure chemicals or mixtures of chemicals with similar true vapor pressures. Examples would include benzene, styrene, and alcohols). Liquids and vapors in the bulk storage and transfer operations can be organic or hydrocarbon in nature. Example would include all of the above including acids and bases. All those chemical should keep in the right storage tank. Design and safety concern has come to a great concern as reported case of fires and explosion for the storage tank has been increasing over the years and these accident cause injuries and fatalities. Spills and tank fires not only causing environment pollution, there would also be severe financial consequences and significant impact on the future business due to the industry reputation.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 7 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
TYPES OF STORAGE TANKS Seven types of vessels are used to store volatile organic liquids: 1. Fixed-roof tanks; 2. External floating roof tanks; 3. Internal floating roof tanks; 4. Domed external floating roof tanks; 5. Horizontal tanks; 6. Pressure tanks; and 7. Variable vapor space tanks.
The first four tank types are cylindrical in shape with the axis oriented perpendicular to the foundation. These tanks are almost exclusively above ground. Horizontal tanks (i.e., with the axis parallel to the foundation) can be used above ground and below ground. Pressure tanks often are horizontally oriented and "bullet" or spherically shaped to maintain structural integrity at high pressures. They are located above ground. Variable vapor space tanks can be cylindrical or spherical in shape.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 8 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
1. Fixed-Roof Tanks Of currently used tank designs, the fixed-roof tank is the least expensive to construct and is generally considered the minimum acceptable equipment for storing VOL's (volatile organic liquids). A typical fixed-roof tank, which is shown in Figure 1 below, consists of a cylindrical steel shell with a cone- or dome-shaped roof that is permanently affixed to the tank shell. Most recently built tanks are of all-welded construction and are designed to be both liquid- and vapor-tight. However, older tanks may be of riveted or bolted construction and may not be vapor-tight. A breather valve (pressure-vacuum valve), which is commonly installed on many fixed-roof tanks, allows the tank to operate at a slight internal pressure or vacuum. Breather vents are typically set at 0.19 kPa (0.75 in. w.c.) on atmospheric pressure fixed-roof tanks. Because this valve prevents the release of vapors during only very small changes in temperature, barometric pressure, or liquid level, the emissions from a fixed-roof tank can be appreciable. For fixed-roof tanks, the nominal capacity is the geometric volume from the bottom of the tank up to the curb angle, which is a metallic angle that is welded along the periphery at the top of the cylindrical portion of the tank. Additionally, gauge hatches/sample wells, float gauges, and roof manholes provide accessibility to these tanks and also serve as potential sources of volatile emissions. Breather vents may be called conservation vents, although hardly any conservation of vapors occurs at such low pressure settings. Generally, the term conservation vent is used to describe a pressure setting of 17 kPa (67 in. w.c.) or less. Vents with settings greater than 17 kPa (67 in. w.c.) are commonly called `pressure' vents.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 9 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Figure 1: Fixed Roof Tanks 1.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 10 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Figure 2: Fixed Roof Tanks 2
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 11 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
2. External Floating Roof Tanks A typical external floating roof tank consists of an open-topped cylindrical steel shell equipped with a roof that floats on the surface of the stored liquid, rising and falling with the liquid level. The floating roof is comprised of a deck, fittings, and rim seal system. Floating roof decks are constructed of welded steel plates and are of three general types: pan, pontoon, and double deck. Although numerous pan-type decks are currently in use, the present trend is toward pontoon and double-deck type floating roofs. The two most common types of external floating-roof tanks are shown in Figures 3 and 4. Manufacturers supply various versions of these basic types of floating decks, which are tailored to emphasize particular features, such as full liquid contact, load-carrying capacity, roof stability, or pontoon arrangement. The liquid surface is covered by the floating deck, except in the small annular space between the deck and the shell; the deck may contact the liquid or float directly above the surface on pontoons. External floating roof tanks are equipped with a rim seal system, which is attached to the roof perimeter and contacts the tank wall. The rim seal system slides against the tank wall as the roof is raised and lowered. The floating deck is also equipped with fittings that penetrate the deck and serve operational functions. The external floating roof design is such that evaporative losses from the stored liquid are limited to losses from the rim seal system and deck fittings (standing storage loss) and any exposed liquid on the tank walls (withdrawal loss). In external floating roof design. the roof is made to rest on the stored liquid and is free to move with the level of the liquid. These tanks reduce evaporation losses and control breathing losses while filling. They are preferred for storage of petroleum products with a true vapor pressure of 10.3 to 76.5 kPa absolute.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 12 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Figure 3: External Floating Roof Tanks 1
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 13 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Figure 4: External Floating Roof Tanks 2
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 14 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Figure 5: Typical List of Floating Roof Fittings
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 15 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
3. Internal Floating Roof Tanks An internal floating roof tank has both a permanent fixed roof and a floating roof inside. There are two basic types of internal floating roof tanks: tanks in which the fixed roof is supported by vertical columns within the tank; and tanks with a selfsupporting fixed roof and no internal support columns. The fixed roof is not necessarily free of openings but does span the entire open plan area of the vessel. Fixed roof tanks that have been retrofitted to employ an internal floating roof are typically of the first type, while external floating roof tanks that have been converted to an internal floating roof tank typically have a self-supporting roof. Tanks initially constructed with both a fixed roof and an internal floating roof may be of either type. An internal floating roof tank has both a permanently affixed roof and a roof that floats inside the tank on the liquid surface (contact deck) or is supported on pontoons several inches above the liquid surface (noncontact deck). The internal floating roof rises and falls with the liquid level. A typical internal floating roof tank is shown in figure below Contact-type decks include (1) aluminum sandwich panels with a honeycombed aluminum core floating in contact with the liquid; (2) resin-coated, fiberglass-reinforced polyester (FRP), buoyant panels floating in contact with the liquid; and (3) pan-type steel roofs, floating in contact with the liquid with or without the aid of pontoons. The majority of contact internal floating decks currently in VOL service are pan-type steel or aluminum sandwich panel type. The FRP decks are less common. Several variations of the pan-type contact steel roof exist. The design may include bulkheads or open compartments around the perimeter of the deck so that any liquid that may leak or spill onto the deck is contained. Alternatively, the bulkheads may be covered to form sealed compartments (i.e., pontoons), or the entire pan may be covered to form a sealed, double deck, steel floating roof. Generally, construction is of welded steel. Noncontact-type decks are the most common type of deck currently in use, and typically consist of an aluminum deck laid on an aluminum grid framework supported above the liquid surface by tubular aluminum pontoons. The deck skin for the noncontact-type floating decks is typically constructed of rolled aluminum sheets (about 1.5 meters [m] [4.9 feet (ft)] wide and 0.58 millimeter [mm] [0.023 inches (in)] thick). The overlapping aluminum sheets are joined by bolted aluminum clamping bars that run perpendicular to the pontoons to improve the rigidity of the frame. These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 16 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
The deck skin seams can be metal on metal or gasketed with a polymeric material. The pontoons and clamping bars form the structural frame of the floating deck. Deck seams in the noncontact internal floating roof design are a source of emissions. Aluminum sandwich panel contact-type internal floating roofs also share this design feature. The sandwich panels are joined with bolted mechanical fasteners that are similar in concept to the noncontact deck skin clamping bars. Steel pan contact internal floating roofs are constructed of welded steel sheets and therefore have no deck seams. Similarly, the resin-coated, reinforced fiberglass panel decks have no apparent deck seams. The panels are butted and lapped with resin-impregnated fiberglass fabric strips. The internal floating roof physically occupies a finite volume of space that reduces the maximum liquid storage capacity of the tank. When the tank is completely full, the floating roof touches or nearly touches the fixed roof. Consequently, the effective height of the tank decreases, thus limiting the storage capacity. The reduction in the effective height varies from about 0.15 to 0.6 m (0.5 to 2 ft), depending on the type and design of the floating roof employed. All types of internal floating roofs, like external floating roofs, commonly incorporate rim seals that slide against the tank wall as the roof moves up and down. Circulation vents and an open vent at the top of the fixed roof are generally provided to minimize the accumulation of hydrocarbon vapors in concentrations approaching the flammable range. Flame arresters are an option that can be used to protect the vessel from fire or explosion. When these are used, circulation vents are not provided. Tank venting occurs through a pressure-vacuum vent and flame arrestor. The design features of internal floating roof can be summary as follow 1. A truly vapor tight metal to metal clamp beam develops the full strength of the deck skin itself 2. A patented pivot joint eliminates stress at pontoon ends by allowing flexure where it is needed 3. Pontoon saddles support the clamp beams on the pontoon and distribute the concentrated load to assure against localized buckling 4. Bolted connections are corrosion resistant 300 series stainless steel fixings 5. Reduces emissions from fixed roof tanks by up to 97% & meets VOC control and Environmental Protection Standards These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 17 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Figure 6: Internal Floating Roof
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 18 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
4. Domed External Floating Roof Tanks Domed external floating roof tanks have the heavier type of deck used in external floating roof tanks as well as a fixed roof at the top of the shell like internal floating roof tanks. Domed external floating roof tanks usually result from retrofitting an external floating roof tank with a fixed roof. A typical domed external floating roof tank is shown in Figure 7. As with the internal floating roof tanks, the function of the fixed roof is not to act as a vapor barrier, but to block the wind. The type of fixed roof most commonly used is a self supporting aluminum dome roof, which is of bolted construction. Like the internal floating roof tanks, these tanks are freely vented by circulation vents at the top of the fixed roof. The deck fittings and rim seals, however, are basically identical to those on external floating roof tanks. Aluminum dome roof have some advance features : 1. The Clear Span design eliminates the need for interior support structures while high strength aluminum alloys and corrosion resistant materials provide for a long service life. 2. Properly designed tension rings ensure that the lateral force generated by the dome is not translated to the tank shell, eliminating the need for additional tank shell reinforcement or modifications. 3. Beams are designed with an extruded continuous threaded bolting slot. This bolting slot provides more thread engagement area and more pull resistance than in conventional designs. 4. The overlapping panels naturally shed water and are secured in place with a patented Batten Bar and hidden gasket system. This deign allows the roof panels to flex while keeping sheets from puckering and bolts from leaking. 5. Aluminum Dome reduces wind induced vapor losses, aids in odor abatement and provides significant emission credits. 6. Floating roof and seal maintenance are drastically reduced due to the lack of rainwater and UV exposure.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 19 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Figure 7: Dome External Floating Roof
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 20 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
5. Horizontal Tanks Horizontal tanks are constructed for both above-ground and underground service. Figures 8 present schematics of typical underground and above-ground horizontal tanks. Horizontal tanks are usually constructed of steel, steel with a fiberglass overlay, or fiberglass-reinforced polyester. Horizontal tanks are generally small storage tanks with capacities of less than 75,710 L (20,000 gallons). Horizontal tanks are constructed such that the length of the tank is not greater than six times the diameter to ensure structural integrity. Horizontal tanks are usually equipped with pressure-vacuum vents, gauge hatches and sample wells, and manholes to provide accessibility to these tanks. In addition, underground tanks may be cathodically protected to prevent corrosion of the tank shell. Cathodic protection is accomplished by placing sacrificial anodes in the tank that are connected to an impressed current system or by using galvanic anodes in the tank. However, internal cathodic protection is no longer widely used in the petroleum industry, due to corrosion inhibitors that are now found in most refined petroleum products. The potential emission sources for above-ground horizontal tanks are the same as those for fixed-roof tanks. Emissions from underground storage tanks are mainly associated with changes in the liquid level in the tank. Losses due to changes in temperature or barometric pressure are minimal for underground tanks because the surrounding earth limits the diurnal temperature change and changes in the barometric pressure would result in only small losses.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 21 of 87
STORAGE TANK SELECTION AND SIZING
Rev: 02
ENGINEERING DESIGN GUIDELINES
JUNE 2011
(a) Fit pipe Vent line Float vent valve in vent line for over protection Product discharge
Product delivery line
Dielectric bushing providing electrical insulation between tank and all connecting lines Cathodic monitoring system Access manway
Cathodicallyprocessed epoxy coasted steel
Sacrificial anodes Compacted bed of sand or gravel
Striker plate below fill pipe Submerged product delivery pump
(b) Figure 8: schematics of typical above-ground horizontal (a) and underground tanks (b)
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 22 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
6. Pressure Tanks Two classes of pressure tanks are in general use: low pressure (2.5 to 15 psig) and high pressure (higher than 15 psig). Pressure tanks generally are used for storing organic liquids and gases with high vapor pressures and are found in many sizes and shapes, depending on the operating pressure of the tank. Pressure tanks are equipped with a pressure/vacuum vent that is set to prevent venting loss from boiling and breathing loss from daily temperature or barometric pressure changes. The pressure tank allows the pump to run occasionally instead of every time a faucet is opened. The basic system is often enhanced, either by necessity or for improved performance, with a constant pressure delivery system.
Figure 9: Scheme of Pressure Tank
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 23 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
7. Variable Vapor Space Tanks Variable vapor space tanks are equipped with expandable vapor reservoirs to accommodate vapor volume fluctuations attributable to temperature and barometric pressure changes. Although variable vapor space tanks are sometimes used independently, they are normally connected to the vapor spaces of one or more fixed roof tanks. The two most common types of variable vapor space tanks are lifter roof tanks and flexible diaphragm tanks. Lifter roof tanks have a telescoping roof that fits loosely around the outside of the main tank wall. The space between the roof and the wall is closed by either a wet seal, which is a trough filled with liquid, or a dry seal, which uses a flexible coated fabric. Flexible diaphragm tanks use flexible membranes to provide expandable volume. They may be either separate gasholder units or integral units mounted atop fixed roof tanks. Variable vapor space tank losses occur during tank filling when vapor is displaced by liquid. Loss of vapor occurs only when the tank's vapor storage capacity is exceeded.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 24 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Figure 10: Variable Vapor Space Tanks
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 25 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Types of Floating Roof Perimeter Seals External and Domed External Floating Roof Rim Seals Regardless of tank design, a floating roof requires a device to seal the gap between the tank wall and the deck perimeter. A rim seal, or in the case of a two-seal system, the lower (primary) rim seal, can be made from various materials suitable for organic liquid service. The basic designs available for external floating roof rim seals are (1) mechanical (metallic) shoe seals, (2) liquid-filled seals, and (3) (vapor or liquid mounted) resilient foam-filled seals. Figures below depict these three general types of seals. One major difference in seal system design is the way in which the seal is mounted with respect to the liquid surface. Figure below shows a vapor space between the liquid surface and rim seal, whereas in second Figure, the seals rest on the liquid surface. These liquid-filled and resilient foam-filled seals are classified as liquid- or vapor-mounted rim seals, depending on their location. Mechanical shoe rim seals are different in design from liquid-filled or resilient foamfilled rim seals and cannot be characterized as liquid- or vapor-mounted. However, because the shoe and envelope combination precludes contact between the annular vapor space above the liquid and the atmosphere (see below), the emission rate of a mechanical shoe seal is closer to that of a liquid-mounted rim seal than that of a vapor-mounted rim seal.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 26 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Figure `11: Vapor mounted primary seals
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 27 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Figure 12: Liquid-mounted and mechanical shoe primary seals
Mechanical Shoe Seal. A mechanical shoe seal, also known as a "metallic shoe seal" (Figure above), is characterized by a metallic sheet (the "shoe") that is held against the vertical tank wall. Previously the regulations did not specify a height for mechanical shoe seals; however, shoe heights typically range from 75 to 130 centimeters (cm) (30 to 51 in.). These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 28 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
The shoe is connected by braces to the floating deck and is held tightly against the wall by springs or weighted levers. A flexible coated fabric (the "envelope") is suspended from the shoe seal to the floating deck to form a vapor barrier over the annular space between the deck and the primary seal. Liquid-Filled Seal A liquid-filled rim seal (Figure above) may consist of a tough fabric band or envelope filled with a liquid, or it may consist of a flexible polymeric tube 20 to 25 cm (8 to 10 in.) in diameter filled with a liquid and sheathed with a tough fabric scuff band. The liquid is commonly a petroleum distillate or other liquid that will not contaminate the stored product if the tube ruptures. Liquid-filled rim seals are mounted on the liquid product surface with no vapor space below the seal. Resilient Foam-Filled Seal A resilient foam-filled rim seal is similar to a liquid-filled seal except that a resilient foam log is used in place of the liquid. The resiliency of the foam log permits the seal to adapt itself to minor imperfections in tank dimensions and in the tank shell. The foam log may be mounted above the liquid surface (vapor-mounted) or on the liquid surface (liquid-mounted). Typical vapor-mounted and liquid-mounted seals are presented in the Figures above respectively. Secondary Seals on External Floating Roofs A secondary seal on an external floating roof consists of a continuous seal mounted on the rim of the floating roof and extending to the tank wall, covering the entire primary seal. Secondary seals are normally constructed of flexible polymeric materials. Figure below depicts several primary and secondary seal systems. An alternative secondary seal design incorporates a steel leaf to bridge the gap between the roof and the tank wall. The leaf acts as a compression plate to hold a polymeric wiper against the tank wall. A rim-mounted secondary seal installed over a primary seal provides a barrier for volatile organic compound (VOC) emissions that escape from the small vapor space between the primary seal and the wall and through any openings or tears in the seal envelope of a metallic shoe seal (Figure below). Although not shown in Figure below, a secondary seal can be used in conjunction with a weather shield as described in the following section. These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 29 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Another type of secondary seal is a shoe-mounted secondary seal. A shoe-mounted seal extends from the top of the shoe to the tank wall (Figure below). These seals do not provide protection against VOC leakage through the envelope. Holes, gaps, tears, or other defects in the envelope can permit direct exchange between the saturated vapor under the envelope and the atmosphere. Wind can enter this space through envelope defects, flow around the circumference of the tank, and exit saturated or nearly saturated with VOC vapors.
Figure 13: Secondary rim seals These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 30 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Weather Shield A weather shield may be installed over the primary seal to protect it from deterioration caused by debris and exposure to the elements. Though the USA EPA does not accept the installation of a weather shield as equivalent to a secondary seal, there are a large number of existing tanks not affected by high VOC’s that have this configuration. Typically, a weather shield is an arrangement of overlapping thin metal sheets pivoted from the floating roof to ride against the tank wall. The weather shield, by the nature of its design, is not an effective vapor barrier. For this reason, it differs from the secondary seal. Although the two devices are conceptually similar in design, they are designed for and serve different purposes. Internal Floating Roof Rim Seals Internal floating roofs typically incorporate one of two types of flexible, productresistant rim seals: resilient foam-filled seals or wiper seals. Similar to those employed on external floating roofs, each of these seals closes the annular vapor space between the edge of the floating deck and the tank shell to reduce evaporative losses. They are designed to compensate for small irregularities in the tank shell and allow the roof to freely move up and down in the tank without binding. Resilient Foam-Filled Seal A resilient foam-filled seal used on an internal floating roof is similar in design to that described for external floating roofs. Resilient foam-filled seals are shown in Figures above. These seals can be mounted either in contact with the liquid surface (liquidmounted) or several centimeters above the liquid surface (vapor-mounted). Resilient foam-filled seals work because of the expansion and contraction of a resilient material to maintain contact with the tank shell while accommodating varying annular rim space widths. These seals consist of a core of open-cell foam encapsulated in a coated fabric. The elasticity of the foam core pushes the fabric into contact with the tank shell. The seals are attached to a mounting on the deck perimeter and are continuous around the roof circumference. Polyurethane-coated nylon fabric and polyurethane foam are commonly used materials. For emission control, it is important that the mounting and radial seal joints be vapor-tight and that the seal be in substantial contact with the tank shell.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 31 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Wiper Seals Wiper seals are commonly used as primary rim seals for internal floating roof tanks. This type of seal is depicted in Figures above. Wiper seals generally consist of a continuous annular blade of flexible material fastened to a mounting bracket on the deck perimeter that spans the annular rim space and contacts the tank shell. The mounting is such that the blade is flexed, and its elasticity provides a sealing pressure against the tank shell. Such seals are vapor-mounted; a vapor space exists between the liquid stock and the bottom of the seal. For emission control, it is important that the mounting be vapor-tight, that the seal extend around the circumference of the roof, and that the blade be in substantial contact with the tank shell. Three types of materials are commonly used to make the wipers. One type consists of a cellular, elastomeric material tapered in cross section with the thicker portion at the mounting. Rubber is a commonly used material. All radial joints in the blade are joined. A second type of wiper seal construction uses a foam core wrapped with a coated fabric. Polyurethane on nylon fabric and polyurethane foam are common materials. The core provides the flexibility and support, while the fabric provides the vapor barrier and wear surface. A third type of wiper seal consists of overlapping segments of seal material (shingle-type seal). Shingle-type seals differ from the wiper seals discussed previously in that they do not provide a continuous vapor barrier. Secondary Seals for Internal Floating Roof Tanks Secondary seals may be used to provide some additional evaporative loss control over that achieved by the primary seal. The secondary seal is mounted to an extended vertical rim plate, above the primary seal, as shown in Figure above. Secondary seals can be either a resilient foam-filled seal or an elastomeric wiper seal. For a given roof design, using a secondary seal further limits the operating capacity of a tank due to the need to maintain contact with the tank shell or keep the seal from interfering with IFRT fixed-roof rafters when the tank is filled. Secondary seals are not commonly used on internal floating roof tanks that are not affected by the EPA regulations.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 32 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
TYPES OF FLOATING ROOF DECK FITTINGS External and Domed External Floating Roof Deck Fittings Numerous fittings penetrate or are attached to an external floating roof deck. These fittings accommodate structural support components or allow for operational functions. These fittings can be a source of emissions in that they must penetrate the deck. Other accessories are used that do not penetrate the deck and are not, therefore, sources of evaporative loss. The most common fittings relevant to controlling vapor losses are described in the following sections. Access Hatches. An access hatch consists of an opening in the deck with a peripheral vertical well attached to the deck and a removable cover to close the opening as shown in Figure below. An access hatch is typically sized to allow workers and materials to pass through the deck for construction or servicing. The cover can rest directly on the well, or a gasketed connection can be used to reduce evaporative loss. Bolting the cover to the well reduces losses further.
Figure 14: Access Hatch These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 33 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Gauge Float Wells Gauge floats are used to indicate the level of stock within the tank. These usually consist of a float residing within a well that passes through the floating deck, as shown in Figure below. The float is connected to an indicator on the exterior of the tank via a tape passing through a guide system. The float rests on the stock surface within the well, which is enclosed by a sliding cover. Evaporation loss can be reduced by gasketing and/or bolting the connection between the cover and the rim of the well. The cable passes through a bushing located at the center of the cover. As with similar deck penetrations, the well extends into the liquid stock on noncontact floating decks.
Figure 15: Gauge float
Gauge Hatch/Sample Ports Gauge hatch/sample ports provide access for hand gauging the level of stock in the tank and for taking samples of the tank contents. A gauge hatch / sample port consists These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 34 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
of a pipe sleeve through the deck and a self-closing gasketed cover, as shown in Figure below. Gauge hatch/sample ports are usually located under the gauger’s platform, which is mounted on the top of the tank shell. The cover may have a cord attached so that it can be opened from the gauger’s platform. A gasketed cover reduces evaporative losses.
Figure 16: Sample ports
Rim Vents Rim vents are found on tanks equipped with a rim seal system that creates a vapor pocket, such as a mechanical shoe seal or double wiper seal system. The rim vent is connected to the rim vapor space by a pipe and releases any excess pressure or vacuum that is present (Figure below). The rim vapor space is bounded by the floating deck rim, the primary-seal shoe, the liquid surface, and the primary-seal fabric. Rim vents usually consist of weighted pallets that rest on the gasketed surface. These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 35 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Figure 17: Rim vent
Deck Drains Deck drains permit removal of rainwater from the surface of floating decks. Two types of floating roof drainage systems are currently used: closed and open. Closed drainage systems carry rainwater from the surface of the deck to the outside of the tank through a flexible or articulated piping system or through a flexible hose system located below the deck in the product space. Since product does not enter this closed drainage system, there is no associated evaporative loss. Open drainage systems, consisting of an open pipe that extends a short distance below the bottom of the deck, permit rainwater to drain from the surface of the deck into the product. Since these drainpipes are filled with product to the product level in the tank, evaporative loss occurs from the top of the open drainpipes. Two types of roof drains are commonly used in open drainage systems: flush drains and overflow drains. Flush drains (Figure These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 36 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
below) have a drain opening that is flush with the top surface of the double deck. They permit rainwater to drain into the product. Overflow drains (Figure below) consist of a drain opening that is elevated above the top surface of the deck, thereby limiting the maximum amount of rainwater that can accumulate on the deck and providing emergency drainage of rainwater. They are normally used in conjunction with a closed drainage system. Some open deck drains are equipped with an insert to reduce the evaporative loss.
Figure 18: Deck drains
Deck Legs Deck legs prevent damage to fittings underneath the deck and allow for tank cleaning or repair by holding the deck at a predetermined distance from the tank bottom. These supports consist of adjustable or fixed legs attached to the floating deck as shown in These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 37 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Figure below. For adjustable deck legs, the load-carrying element passes through a well or sleeve in the deck.
Figure 19: Deck leg
Slotted and Unslotted Guide Poles and Wells Anti-rotation devices are used to prevent floating roofs from rotating and potentially damaging roof equipment and rim seal systems. A commonly used antirotation device is a guide pole that is fixed at the top and bottom of the tank (Figure below). The guide pole passes through a well in the deck. Rollers attached to the top of the well ride on the outside surface of the guide pole to prevent the floating roof from rotating.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 38 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
The guide pole well has a sliding cover to accommodate limited radial movement of the roof. The sliding cover can be equipped with a gasket between the guide pole and the cover to reduce evaporative loss. The guide pole well can also be equipped with a gasket between the sliding cover and the top of the well to reduce evaporative loss. Openings at the top and bottom of the guide pole provide a means of hand-gauging the tank level and of taking bottom samples. In the slotted guide pole/sample well application, the well of the guide pole is constructed with a series of drilled holes or slots that allow the product to mix freely in the guide pole and thus have the same composition and liquid level as the product in the tank. Evaporative loss from the guide pole can be reduced by modifying the guide pole or well, or by placing a removable float inside the pole. Deck fitting factors for slotted guide poles without pole sleeves were determined from test data on fittings where the float top or float wiper was positioned at or above the sliding cover elevation. Tests were not conducted with floats where the top of the float or wiper was below the sliding cover elevation (“short” floats); emissions from such a configuration are expected to be somewhere between those for guide poles with and without floats, depending upon the float height. When a pole sleeve is used, the evaporative loss will not be affected by the height of the float within the well, since the purpose of the pole sleeve is to restrict the flow of vapor from the vapor space below the deck into the slotted guide pole.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
Page 39 of 87
KLM Technology Group
STORAGE TANK SELECTION AND SIZING
Practical Engineering Guidelines for Processing Plant Solutions
ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Figure 20: Slotted and unslotted guidepoles
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 40 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Vacuum Breakers The purpose of a vacuum breaker is to allow for the exchange of vapor and air through the floating roof during filling and emptying. Vacuum breakers are designed to be activated by changes in pressure or liquid level, or strictly by mechanical means. Mechanical vacuum breakers are activated when the deck is either being landed on its legs or floated off its legs to equalize the pressure of the vapor space across the deck. This is accomplished by opening a deck penetration that usually consists of a well formed of pipe or framing on which rests a cover (Figure below). Attached to the underside of the cover is a guide leg long enough to contact the tank bottom as the external floating deck approaches the tank bottom. When in contact with the tank bottom, the guide leg mechanically opens the breaker by lifting the cover off the well. When the leg is not contacting the bottom, the penetration is closed by the cover resting on the well. The closure may or may not have a gasket between the cover and neck. Since the purpose of the vacuum breaker is to allow the free exchange of air and/or vapor, the well does not extend appreciably below the deck. The gasket on the underside of the cover, or conversely on the upper rim of the well, provides a small measure of emission control during periods when the roof is free floating and the breaker is closed.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 41 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Figure 21: Vacuum breaker
Internal Floating Roof Fittings Numerous fittings penetrate or are attached to an internal floating deck. These fittings serve to accommodate structural support components or to allow for operational functions. The fittings can be a source of evaporative loss in that they require penetrations in the deck. Other accessories are used that do not penetrate the deck and are not, therefore, sources of evaporative loss. The most common fittings relevant to controlling vapor losses are described in the following sections. The access hatches, deck legs, vacuum breakers, and automatic gauge float wells for internal floating roofs are similar fittings to those described earlier for external floating roofs.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 42 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Column Wells The most common fixed-roof designs (Figure below) are normally supported from inside the tank by means of vertical columns, which necessarily penetrate the floating deck. (Some fixed roofs are entirely self-supporting and, therefore, have no support columns.) Columns are made of pipe with circular cross sections or of structural shapes with irregular cross sections (built-up). The number of columns varies with tank diameter from a minimum of 1 to over 50 for very large tanks. A typical fixed roof support column is shown in Figure below. The columns pass through deck openings via peripheral vertical wells. With noncontact decks, the well should extend down into the liquid stock. Generally, a closure device exists between the top of the well and the column. Several proprietary designs exist for this closure, including sliding covers and fabric sleeves, which must accommodate the movements of the deck relative to the column as the liquid level changes. A sliding cover rests on the upper rim of the column well (which is normally fixed to the deck) and bridges the gap or space between the column well and the column. The cover, which has a cutout, or opening, around the column, slides vertically relative to the column as the deck raises and lowers. At the same time, the cover slides horizontally relative to the rim of the well. A gasket around the rim of the well reduces emissions from this fitting. A flexible fabric sleeve seal between the rim of the well and the column (with a cutout, or opening to allow vertical motion of the seal relative to the columns) similarly accommodates limited horizontal motion of the roof relative to the column. A third design combines the advantages of the flexible fabric sleeve seal with a well that excludes all but a small portion of the liquid surface from direct exchange with the vapor space above the floating deck.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
Page 43 of 87
KLM Technology Group
STORAGE TANK SELECTION AND SIZING
Practical Engineering Guidelines for Processing Plant Solutions
ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Figure 22: Fixed Roof Support Column
Sample Pipes or Wells A sample well may be provided to allow liquid stock sampling. Typically, the well is funnel-shaped to allow for easy entry of a sample thief. A closure is provided, which is typically located at the lower end of the funnel and which frequently consists of a horizontal piece of fabric slit radially to allow thief entry. The well should extend into the liquid stock on noncontact decks. Alternately, a sample well may consist of a slotted pipe extending into the liquid stock equipped with an ungasketed or gasketed sliding cover. Ladder Wells Some tanks are equipped with internal ladders that extend from a manhole in the fixed roof to the tank bottom. The deck opening through which the ladder passes is
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 44 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
constructed with similar design details and considerations to those for column wells. A typical ladder and well are shown in Figure below.
Figure 23: Ladder and well
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 45 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
DEFINITIONS Above Ground Storage Tank (AST) - any one or combination of tanks, including pipes connected thereto and any ancillary equipment and containment system, that is used to contain an accumulation of liquids or gases, and the volume of which, including the volume of connected piping. Accuracy - The ability of a measuring instrument to indicate values closely approximating the true value of the quantity measured. Atmospheric Storage Tank – a storage tank which has been designed to operate at pressures from atmospheric through 0.5 psig Autoignition Temperature - The temperature to which a flammable mixture of vapor and air in the explosive range must be heated for ignition to occur spontaneously without external source of ignition. API Gravity (Relative Density) - A means used by the petroleum industry to express the density of petroleum liquids. API gravity is measured by a hydrometer instrument having a scale graduated in degrees API. The relation between API gravity and relative density (formerly called specific gravity) is: API Gravity at 60 Deg. F. =
141.5 Relative Density 60F/60F
- 131.5
Ballast Water - Oil contaminated water contained in the cargo compartments of marine vessels. Ballast water is taken aboard empty or near empty vessels to provide a safe level of stability for the vessel. Tankers arriving at a shipping dock to take on product, discharge ballast water into a shore side storage tanks for subsequent wastewater treatment. This operation is known as de-ballasting. Barrel (BBL) - A unit of volume equal to 42 U.S. gallons or 9702.0 cubic inches. Blocked Operation - The use of a single process unit alternately in more than one operation to manufacture various grades of product. Lube oils and certain chemicals such as linear paraffins are often made in blocked operation. Breathing Loss - Loss associated with thermal expansion and contraction of the vapor space, resulting from the daily temperature cycle or any such temperature cycle that can be induced by weather conditions such as rainstorms. These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 46 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
BS&W (Bottom sediment and water) - The sludge and water which settles to the bottom of storage tanks, as measured by standard test method and expressed in volume percent. Calibration Tables (Gauge Or Tank Tables, Innage/ Ullage Tables) - Tables developed by recognized industry methods that represent volumes in each tank according to the liquid (innage) or empty space (ullage) measured in the tank. The tables are entered with linear measurements (for example, feet, inches, meters, centimeters) to obtain calibrated volumes (for example, barrels, cubic meters or cubic feet). Closed Gauging System - A method of obtaining measurements of the tank contents without opening the tank. This may be accomplished by using automatic tank gauges or by taking measurements through a pressure/vapor lock standpipe. This type of gauging is done extensively on vessels with inert gas systems. Closed System Gauging Unit - Closed gauging system measurement equipment specially designed to be used with a specific type of standpipe/vapor lock. The unit may have a single purpose such as taking temperature, ullages, watercuts or samples, or may be a combined unit capable of performing all necessary measurement functions. Coalescer - A device used to cause the separation and removal of one liquid from another such as water from a petroleum liquid. Cone Bottom Up - A tank bottom configuration that slopes up from the side to the center. This configuration is usually limited to locations with poor soil conditions, small diameter tanks such as in marketing terminals, and molten sulfur tanks. Cone Bottom Down - A tank bottom configuration that slopes down from the side to the center. The apex for either cone bottom up or down is generally but not necessarily located at the center of the tank. Critical Zone - A term used to define the liquid level in a floating roof type storage tank from the point where floating of the roof begins to the point where the roof is fully floating. Sometimes known as the “inaccurate zone” or “partially floating region.” The critical zone is identified on tank calibration tables where appropriate.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 47 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Density - The density of a homogeneous substance is the ratio of its mass to its volume. The density varies as the temperature changes and it is usually expressed as the mass per unit volume at a specified temperature. Absolute Density – The mass of a substance per unit volume at a specified temperature. Relative Density - The ratio of the mass of a given volume of fluid to the mass of an equal volume of pure water at the same temperature and pressure. Relative density replaces the term “specific gravity”. Relative Density At 60 - Fluid relative density measured against water with both materials at 60 degrees F and reference pressure of 14.696 psia (or equilibrium pressure). Equivalent to “RD 60/60”. Dike - A dike is an earthen or concrete wall providing a specified liquid retention for the enclosed vessel(s). Dome Roof - A fixed truss roof design that is in the shape of a dome. The dome roof can be designed to carry small internal pressures of 1 to 1.5 psig (7 to 10 kPa gage). In special cases, roofs can be designed for higher pressure, but such designs are usually not economical. Explosive Limits - These are the limits of the explosive (flammable) range, i.e., the range between the minimum and maximum concentrations of a flammable vapor in air, which form explosive mixtures. These conditions may exist in the vapor space of ordinary fixed roof tanks. Flash Point - The lowest temperature of a petroleum liquid at which sufficient vapors are produced to form a mixture with air that will ignite in the presence of an ignition source, as measured under specified conditions in standardized test apparatus. Floating Roof - A roof which floats on the surface of the liquid in a tank. The floating roof is used to eliminate a vapor space in atmospheric storage tanks, thereby reducing evaporation losses and providing increased safety. A floating roof may be installed in either an open roof (external floater) or a cone roof tank (internal floater). Flush Nozzle - A rectangular tank nozzle which enters the side of the tank and has the underside flush with the tank bottom. These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 48 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Frangible Roof - A frangible roof is basically a weak roof-to-shell seam which will rupture before any other part of the tank fails if over pressurized. Gauging Equipment - Equipment that indicates the level of a liquid inside the tank relative to the tank base line. Gauging - A process of measuring height of a liquid in a storage tank usually using a weighted graduated steel tape and bob. Alternate Innage Gauge - The innage obtained by subtracting the measured distance between the surface of the liquid in the tank and the reference point from the official reference height of the tank. Alternate Ullage Gauge - The ullage obtained by subtracting the measured height of the liquid in the tank from the official reference height of the tank. Innage Gauge (Dip, Sounding) - The height of the liquid surface from the bottom of the tank (or datum plate). Ullage (Outage) Gauge - The distance from the liquid surface to the top of the tank (or reference point). Gross Tankage Volume - The total geometric tank volume below the shell height. High Temperature Tanks - Tanks which are operated at temperatures above 265°F (130°C). Low Pressure Storage Tank - a storage tank which has been designed to operate at pressures above 0.5 psig but not more than 15 psig.
Net Tank Volume - The total usable volume inside a tank. Net volume equals gross volume less the volume equivalent attributable to tank heel. Pour Point - The lowest temperature at which oil will pour or flow when it is chilled under prescribed ASTM test conditions. Pressure - The amount of force exerted on a unit of area by a fluid.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
Page 49 of 87
KLM Technology Group
STORAGE TANK SELECTION AND SIZING
Practical Engineering Guidelines for Processing Plant Solutions
ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Absolute Pressure - The pressure referenced to a perfect vacuum as zero pounds per square inch absolute. Atmospheric Pressure - The pressure exerted by the atmosphere. Although this pressure varies with altitude, barometric pressure and humidity, the atmospheric pressure can be defined in custody transfer contracts, or by state and federal authorities. Atmospheric pressure is most often stated as 14.696 pounds per square inch absolute. Back Pressure control valve.
-
The operating pressure level measured upstream from a
Gauge Pressure - That pressure measured relative to atmospheric pressure as zero, usually designated psig. High Vapor Pressure - A fluid which, at the measurement or proving temperature, has a vapor pressure that is equal to or higher than atmospheric pressure. Low Vapor Pressure - A fluid which, at the measurement or proving temperature, has a vapor pressure that is less than atmospheric pressure. Reid Vapor Pressure (RVP) - The vapor pressure of a fluid at 100 degrees Fahrenheit as determined by test method ASTM D 323-58. RVP is one of the important specifications for gasoline and solvents. It is a measure of the vapor pressure of a sample at 100°F (38°C), in the presence of air. A test is made in a bomb, and the results are reported in pounds per square inch absolute. Static Pressure - The pressure in a fluid that is exerted normal to the surface. In a moving fluid, the static pressure is measured at right angles to the direction of flow.
Pressure Storage - A storage vessel whose design pressure is greater than 2.5 psig (17 kPa). Pressure Vacuum Vent (P-V Vent) - A particular type of vent used on tank roofs which reduces normal breathing losses and protects the tank from external ignition sources. Unlike the open type of vent, the P-V vent is normally closed, but opens under the action of slight internal pressure or vacuum.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 50 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Pyrophoric Material - A material which forms under oxygen deficient conditions, which when exposed to air, will oxidize and slowly build up in temperature until glowing red particles can ignite flammable mixtures. Refrigerated Storage - Any conventional storage vessel in which the contents are stored below ambient temperature. Rundown Line - The pipeline from a process unit to a tank, through which the unit's production flows. Sampling - The process of obtaining a sample of the material in the tank, container or pipeline to use for testing or other purposes. This can be achieved by automatic or manual means. The following are the most common types of samples taken: All-Levels Sample - A sample obtained by lowering a weighted, stoppered bottle or beaker or bottle to a point 1 foot (0.3 meter) above the free water level and then, with a sharp jerk of the line opening the sampler and raising it at a rate that it is about 75% full (a maximum of 85% full) as it emerges from the liquid. Automatic Sample - A sample taken by automatic means. The two basic types of automatic samples are: Flow-Proportional Sample - A sample taken by an automatic sampler from a pipeline at a rate that is proportional to the liquid flow rate. Time-Proportional Sample - A sample taken from a pipeline at regular intervals during a batch transfer period. Bottom Sample - A spot sample taken from the material at the bottom of the tank. Lower Sample - A spot sample obtained at the midpoint of the lower third of the tank contents. Middle Sample - A spot sample obtained at the midpoint of the middle of the tank contents. Running Sample - A sample obtained by submerging an unstoppered beaker or bottle from the surface of the liquid to a point as near as possible to the These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
Page 51 of 87
KLM Technology Group
STORAGE TANK SELECTION AND SIZING
Practical Engineering Guidelines for Processing Plant Solutions
ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
shore tank draw off point or about one foot above the level of the free water in a ship tank, and then raising it without letting it rest, at a rate so that it will be about 75% full as it emerges from the liquid.
Spot Sample - A sample taken at a specific “spot” within a tank using a stoppered bottle or beaker and lowering it to the level of desired sample then opening it and allowing it to remain at that level until full. A thief or a zone sampler may also be used to obtain spot samples. Tap Sample pipeline.
-
A sample taken from a valve or connection on a tank or
Upper Sample - A spot sample obtained at the midpoint of the upper of the tank contents. Upper, Middle, Lower Samples - Spot samples taken from the upper third, the middle and lower thirds of the liquid in the tank. The samples so taken may then be composited or analyzed separately. Seals for Floating Roof - The mechanism that seals the space between the periphery of the floating roof and the tank shell. The primary seal separates the stored liquid from the atmosphere by sealing the gap between the floating roof and the tank shell. Secondary seals are flexible metal or rubber seals that span the gap between the tank wall and the floating roof, above the primary seal. Sludge - The material that settles to the bottom of crude tanks and which cannot be removed by normal pumping means. Tank Stripping Operation - The complete pumping out of a storage tank until it is empty. Temporary pumps are usually used for this operation. Underground Storage Tank (UST) - means any one or combination of tanks, including underground pipes connected thereto and any underground ancillary equipment and containment system, that is used to contain an accumulation of regulated substances, and the volume of which, including the volume of underground pipes connected thereto, is ten percent or more beneath the surface of the ground.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 52 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Volume - The amount of space occupied by a fluid at certain conditions of temperature and pressure. Various types of VOLUMES used in marine custody transfer are defined as follows: Gross Observed Volume (GOV) - The total volume of all petroleum liquids and sediment and water, excluding free water, at observed temperature and pressure. Gross Standard Volume (GSV) - The total volume of all petroleum liquids and sediment and water, excluding free water, corrected by the appropriate volume correction factor (Ctl) for the observed temperature and API gravity, relative density, or density to a standard temperature such as 60F or 15C and also corrected by the applicable pressure correction factor (Cpl) and meter factor. Indicated Volume - The change in meter reading that occurs during a receipt or delivery. Net Standard Volume (NSV) - The total volume of all petroleum liquids, excluding sediment and water and free water, corrected by the appropriate volume correction factor (Ctl) for the observed temperature and API Gravity, relative density, or density to a standard temperature such as 60F or 15C and also corrected by the applicable pressure correction factor (Cpl) and meter factor. On Board Quantity (OBQ) - The material remaining in vessel tanks, void spaces, and/or pipelines prior to loading. On-board quantity includes water, oil, slops, oil residue, oil/water emulsions, sludge, and sediment. Remaining On Board (ROB) - The material remaining in vessel tanks, void spaces, and/or pipelines after discharge. Remaining on board quantity includes water, oil, slops, oil residue, oil/water emulsions, sludge, and sediment. Total Calculated Volume (TCV) - The total volume of all petroleum liquids and sediment and water, corrected by the appropriate volume correction factor (Ctl) for the observed temperature and API gravity, relative density, or density to a standard temperature such as 60F or 15C and also corrected by the applicable pressure factor (Cpl) and meter factor, and all free water measured at observed temperature and pressure (gross standard volume plus free water). Total Observed Volume (TOV) - The total measured volume of all petroleum liquids, sediment and water, and free water at observed temperature and pressure.
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
Page 53 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
NOMENCLATURE c CS D Di Do E f g hh hl HS HVO HRO I icr KC KD KE KFi KFai KFbi KN KP KRa KRb KS Kv LF LR LS LT LW LWD m mL MV N n
Corrosion factor Shell clingage factor, bbl/1,000 ft2 Tank diameter, ft Tank inlet diameter, ft Outlet diameter tank, ft Welded joint efficiencies Allowable stress, psi Gravity acceleration, m/s2 Head height, in Liquid level in tank, ft Tank shell height, ft Vapor space outage, ft Roof outage, ft Daily total solar insolation on a horizontal surface, Btu/ft2 day Inside corner radius, in Product factor Deck seam loss per unit seam length factor, lb-mole/ft-yr Vapor space expansion factor Loss factor for a particular type of deck fitting, lb-mole/yri Zero wind speed loss factor for a particular type of fitting, lb-mole/yr Wind speed loss factor a particular type of fitting, lb-mole/(mph)myr Working loss turnover factor Working loss product factor Zero wind speed rim seal loss factor, lb-mole/ft-yr Wind speed, lb-mole/(mph)nft-yr Vented vapor saturation factor Fitting wind speed correction factor. Deck fitting loss, lb/yr Rim seal loss, lb/yr Standing storage losses, lb/yr Total losses, lb/yr Working losses, lb/yr Withdrawal loss, lb/yr Loss factor for a particular type of deck fitting. Liquid mass, lb Vapor molecular weight, lb/lb-mole Number of turnovers per year Seal-related wind speed exponent
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
KLM Technology Group Practical Engineering Guidelines for Processing Plant Solutions
NC Nf ρL P PA Pdesign Poperasi Phidrostatik PVA Q R r rc RS SD sf SR TAmax TAmin th TL tt v VL VT VV W
Page 54 of 87
STORAGE TANK SELECTION AND SIZING ENGINEERING DESIGN GUIDELINES
Rev: 02
JUNE 2011
Number of fixed roof support columns Typical number of fitting Liquid density, lb/ft3 Vapor pressure function Atmospheric pressure, psia Design pressure, psi Operation tank pressure, atm Hidrostatik pressure, atm Vapor pressure liquid surface temperature, psia Annual net throughput, bbl/yr Ideal gas constant , psia ft3/lb-mole °R inlet spherical, in Radius of crown, in Tank shell radius, ft Deck seam length factor, ft/ft2 Straight flange, in Tank cone roof slope, ft/ft Daily maximum ambient temperature, °R Daily minimum ambient temperature, °R Head thickness, in Daily average liquid surface temperature, °R Tank thickness, in Average ambient wind speed at tank site, mph Volume liquid, ft3 Tank volume, ft3 Vapor space volume, ft3 Stress intensification factor for torispherical head
Greek Letters α ρ
Tank paint solar absorptance. Density, lb/ft3
Superscript L V
liquid phase vapor phase
These design guideline are believed to be as accurate as possible, but are very general and not for specific design cases. They were designed for engineers to do preliminary designs and process specification sheets. The final design must always be guaranteed for the service selected by the manufacturing vendor, but these guidelines will greatly reduce the amount of up front engineering hours that are required to develop the final design. The guidelines are a training tool for young engineers or a resource for engineers with experience. This document is entrusted to the recipient personally, but the copyright remains with us. It must not be copied, reproduced or in any way communicated or made accessible to third parties without our written consent.
