Title: Appendix L, Design Specific Gravity Change

Agenda Item: 650-766

Date: November 13 2012

Contact: Name : Peter Mignosa

Company : British Petroleum

Phone : (310) 847-3938

E-mail :

Purpose: Inconsistent description of the design specific gravity throughout the standard compared with the description in Appendix L. SGD agreed to proceed with making the standard more consistent.

Source: Inquiry 4/12 meeting

Revision: 0

Impact: The business impact of this item is neutral.

Rationale: Inconsistencies in the code may lead to confusion. Making the definition and all references to specific gravity in the code consistent any confusion should be eliminated.

Proposal:

5.7.7.6 The minimum width of the tank-bottom reinforcing plate at the centerline of the opening shall be 250 mm (10 in.) plus the combined nominal thickness of the shell plate in the cleanout-opening assembly and the shell reinforcing plate.

The nominal thickness of the bottom reinforcing plate shall be not less than that determined by the following equation:

In SI units:

where

tb = minimum thickness of the bottom reinforcing plate, in mm,

h = vertical height of clear opening, in mm,

b = horizontal width of clear opening, in mm,

H = maximum design liquid level (see 5.6.3.2), in m,

G = design specific gravity, (for the purpose of this equation, shall not be less than

1.0).

In US Customary units:

where

tb = minimum thickness of the bottom reinforcing plate, (in.),

h = vertical height of clear opening, (in.),

b = horizontal width of clear opening, (in.),

H = maximum design liquid level (see 5.6.3.2), (ft),

G = design specific gravity, (for the purpose of this equation, shall not be less than

1.0).

5.7.8.4 The reinforcement for a flush-type shell connection shall meet the following requirements:

f. The width of the tank-bottom reinforcing plate at the centerline of the opening shall be 250 mm (10 in.) plus the combined nominal thickness of the shell plate in the flush-connection assembly and the shell reinforcing plate. The thickness of the bottom reinforcing plate shall be calculated by the following equation (see 5.7.7.6):

In SI units:

where

tb = minimum thickness of the bottom reinforcing plate, in mm,

h = vertical height of clear opening, in mm,

b = horizontal width of clear opening, in mm,

H = maximum design liquid level (see 5.6.3.2), in m,

G = design specific gravity, (for the purpose of this equation, shall not be less than

1.0).

In US Customary units:

where

tb = minimum thickness of the bottom reinforcing plate, (in.),

h = vertical height of clear opening, (in.),

b = horizontal width of clear opening, (in.),

H = maximum design liquid level (see 5.6.3.2), (ft),

G = design specific gravity, (for the purpose of this equation, shall not be less than

1.0).

APPENDIX A— Optional Design Basis for Small Tanks

A.1.5 Typical sizes, capacities, and shell-plate thicknesses are listed in Tables A-1a through A-4b for a design in accordance with A.4 (joint efficiency = 0.85; design specific gravity = 1.0; and corrosion allowance = 0).

A.4 Thickness of Shell Plates

A.4.1 The nominal thicknesses of shell plates shall not be less than that computed from the stress on the vertical joints, using the following formula:

In SI units:

where

t = nominal thickness, in mm (see 5.6.1.1),

D = nominal diameter of the tank, in m (see 5.6.1.1, Note 1),

H = design liquid level, in m (see 5.6.3.2),

G = design specific gravity of the liquid to be stored, as specified by the Purchaser. The design specific gravity shall not be less than 1.0,

E = joint efficiency, which is either 0.85 or 0.70 (see A.3.4),

CA = corrosion allowance, in mm, as specified by the Purchaser (see 5.3.2).

In US Customary units:

where

t = nominal thickness (in.) (see 5.6.1.1),

D = nominal diameter of the tank (ft) (see 5.6.1.1, Note 1),

H = design liquid level (ft) (see 5.6.3.2),

G = design specific gravity of the liquid to be stored, as specified by the Purchaser. The design specific gravity shall not be less than 1.0,

E = joint efficiency, which is either 0.85 or 0.70 (see A.3.4),

CA = corrosion allowance (in.), as specified by the Purchaser (see 5.3.2).

APPENDIX C— External Floating Roofs

C.3.4.1 Floating roofs shall have sufficient buoyancy to remain afloat on liquid with a specific gravity of the lower of the product design specific gravity or 0.7 and with primary drains inoperative for the following conditions:

C.3.4.3 Any penetration of the floating roof shall not allow product to flow onto the roof under design conditions.

C.3.4.34 The sag of the roof deck under design conditions and the minimum design specific gravity (0.7 See C.3.4.1 for minimum value) of the stored liquid shall be considered in establishing the minimum elevations of all roof penetrations.

APPENDIX E— Seismic Design of Storage Tanks

E.2.2 Notations

G Design specific gravity

APPENDIX H— Internal Floating Roofs

H.4.2 Internal Floating Roof Design

H.4.2.1 Buoyancy Requirements

H.4.2.1.1 All internal floating roof design calculations shall be based on the lower of the product design specific gravity or 0.7 (to allow for operation in a range of hydrocarbon service), regardless of any higher design specific gravity that might be specified by the Purchaser.

H.5.3.3 The use of emergency overflow slots shall only be permitted if specified by the Purchaser. When emergency overflow slots are used, they shall be sized to discharge at the pump-in rates for the tank. The greater of the product design specific gravity or 1.0 shall be used to determine the overflow slot position so that accidental overfilling will not damage the tank or roof or interrupt the continuous operation of the floating roof. Overflow discharge rates shall be determined by using the net open area (less screen) and using a product level (for determining head pressure) not exceeding the top of the overflow opening. The overflow slots shall be covered with a corrosion-resistant coarse-mesh screen (13 mm [1/2 in.] openings) and shall be provided with weather shields (the closed area of the screen must be deducted to determine the net open area). The open area of emergency overflow slots may contribute to the peripheral venting requirement of H.5.2.2.1 provided that at least 50% of the circulation-vent area remains unobstructed during emergency overflow conditions. The floating-roof seal shall not interfere with the operation of the emergency overflow openings. Overflow slots shall not be placed over the stairway or nozzles unless restricted by tank diameter/height or unless overflow piping, collection headers, or troughs are specified by the Purchaser to divert flow.

APPENDIX K— Sample Applications of the Variable-
Design-Point Method to Determine Shell-Plate Thickness

K.1 Variable-Design-Point, Example #1

K.1.1 Data

[ ] Design condition [x] Test condition

Design Sspecific gravity of liquid, G: 1.0

APPENDIX L— API Std 650 Storage Tank Data Sheet

L.3 Specific Instructions

L.3.1 Line-by-Line Instructions

Each place for data entry (numbered lines, boxes, table cells, etc.) on the Data Sheet shall be completed. In no case should a line be left blank. Marking “NA” (not applicable), “Later,” “TBD” (to be determined), or other such terminology can be used. The “Later” and “TBD” notations shall be edited to reflect subsequent decisions and as-built configurations (see W.1.2).

Use consistent units for all dimensions and other data on the Data Sheet. Show appropriate units for every appropriate numerical entry.

The following numbered items correspond to the numbered lines and numbered tables on the Data Sheet:

5. Products Stored

– Liquid: Specify liquid(s) to be stored in the tank.

– Maximum Design Specific Gravity: Enter specific gravity of the stored liquid(s) at designated temperatures. Use greatest value of all products when tanks are to be designed for multiple products.

API / API Std 650 Storage Tank
Data Sheet / Data Sheet Status: ______
Page 1 of 8
* For boxes marked with *, if blank, Mfr. shall determine and submit as per Appendix L. For all lines, see Appendix L for line-by-line instructions.
GENERAL Special Documentation Package Requirements: ______
Measurement Units to be used in API Std 650: SI US Customary
1. Manufacturer* ______Contract No.* ______
Address* ______
Mfg. Serial No.* ______Year Built* ______Edition & Addendum to API 650* ______
2. Purchaser ______Contract No. ______
Address ______
Tank Designation ______
3. Owner/Operator ______Location ______
4. Size Limitations* ______Tank Diameter* ______Shell Height* ______
Capacity: Maximum* ______Net Working* ______Criteria:* ______
5. Products Stored:
Liquid ______Max. S.G Design Specific Gravity.: ______at ______-__
Blanketing Gas______Vapor Pressure ______PSIA at Max. Operating Temp.
% Aromatic ______Suppl. Spec. ______H2S Service? Yes No Suppl. Spec. ______
Other Special Service Conditions? Yes No Suppl. Specs.______
DESIGN AND TESTING Purchaser to Review Design Prior to Ordering Material? Yes No
6. Applicable API Standard 650 Appendices:* A B C F G H I J L M O P S U V W
7. Max. Design. Temp. _______ Design Metal Temp.* _____--__ Design Liquid Level* ______
Design Pressure ______External Pressure ______Pressure Combination Factor ______
Maximum Fill Rate ______Maximum Emptying Rate ______
Flotation Considerations? Yes No Flot. Suppl. Spec:* ______Applied Supplemental Load Spec.______
8. Seismic Design? Yes No Appendix E Alternate Seismic Criteria ______Seismic Use Group ______
MBE Site Class ______Vertical Seismic Design? Yes No Vertical Ground Motion Accelerator Av: ______
Basis of Lateral Acceleration (Select one): Mapped Seismic Parameters? Ss ____S1 ____ S0 ____; Site-Specific Procedures?: MCE Design Required? Yes No ; Other (Non-ASCE) Methods ______
Freeboard Required for SUG I Design Roof Tie Rods @ Outer Ring?* Yes No
9. Wind Velocity for non-U.S. sites, 50-yr wind speed (3-sec Gust)* ______
Top Wind Girder Style* ______Dimensions* ______Use Top Wind Girder as Walkway? Yes No
Intermediate Wind Girders?* Yes No Intermediate Wind Girder Style* ______Dimensions*______
Check Buckling in Corroded Cond.? Yes No
10. Shell Design: 1-Ft Mthd?* Yes No ; Variable-Des-Pt Mthd?* Yes No Alternate ; Elastic Anal. Mthd?* Yes No Alternate
Plate Stacking Criteria* Centerline-Stacked? Yes No Flush-Stacked? Yes No Inside Outside
Plate Widths (Shell course heights) and Thicknesses * Numbers below Indicate Course Number.
1. ______2. ______3. ______4. ______5. ______
6. ______7. ______8. ______9. ______10. ______
11. ______12. ______13. ______14. ______15. ______
Joint Efficiency* ______% Shell-to-Bottom Weld Type* ______Shell-to-Bottom Weld Insp Mthd* ______
Approvals: / Revisions: / Title:
By: Ck’d: Date:
Drawing No.: Sheet ___ of ___
API / API Std 650 Storage Tank
Data Sheet / Page 2 of 8
* If box is blank, Manufacturer shall determine and submit as per Appendix L.
11. Open-Top and Fixed Roofs: (See Sheet 6 for Floating Roofs) Open Top? * Yes No
Fixed Roof Type* ______Roof Support Columns*: Pipe Or Structural Shape ______
Cone Slope* ______. Dome or Umbrella Radius* ______Weld Joints* ______
(Lap, Butt, Other)
Seal Weld Underside of: Lap-Joints? Yes No ; Seal Weld Underside of Wind Girder Joints? Yes No
Gas-tight? Yes No Joint Efficiency* ______%
Minimum Roof Live Load ______psf Balanced Snow Load ______psf Unbalanced Snow Load ______psf
App. Suppl. Load Spec.* ______Column Lateral Load ______
Normal Venting Devices*______Emergency Venting Devices* ______
For Non-Frangible Roofs: Seal Weld Roof Plates to Top Angle on the Inside? Yes No ; Weld rafters to Roof Plates Yes No
Roof-to-Shell Detail* ______Radial Projection of Horizontal Component of Top Angle* Inward Outward
12. Bottom: Thickness* ______Style* ______Slope* ______. Weld Joint Type* ______
Provide Drip Ring? Yes No Alternate Spec. ______
Annular Ring? Yes No Annular Ring: Minimum Radial Width* ______Thickness* ______
13. Foundation: Furnished by*______Type* ______
Soil Allow. Bearing Pressure* ______Per Spec.* ______Anchors: Size* _____ Qty* _____
Foundation Design Loads: Base Shear Force: Wind* _____ Seismic* _____ Overturning Moment: Wind* ______Seismic* _____
Ring Forces: Weight of Shell + Roof New* ______Corroded* ______Roof Live Load* ______Internal Pressure* ______
Partial Vacuum* ______Wind* ______Seismic* ______
Bottom Forces: Floor Wt. New* ______Corroded* ______Product Wt.* ______Water Wt.* _____ Internal Pressure* ______
Partial Vacuum* ______Other Foundation Loads* ______Min. Projection of Fdn. Above Grade: ______
14. Responsibility for Heating Water, if Required: Purchaser Manufacturer
Hydro-Test Fill Height* ______Settlement Measurements Required ? Yes No Extended Duration of Hydro-Test:______
Predicted Settlement Profile is Attached
Responsibility for Setting Water Quality: Purchaser Manufacturer Supplemental Test Water Quality Spec. ______
Test Water Source & Disposal Tie-In Locations ______Hydro-Test Appendix J Tank? Yes No
Post-Pressure-Test Activities Required of the Manufacturer: Broom Clean Potable Water Rinse Dry Interior
Other ______
15. Inspection by ______in Shop; ______in Field
Supplemental NDE Responsibility ______Supplemental NDE Spec. ______
(Purch., Mfg., Other)
Positive Material Identification? Yes No PMI Requirements:______
Max. Plate Thickness for Shearing ______
Must Welds not exceeding 6 mm (1/4 in.) Be Multi-Pass? Yes No Must Welds greater than 6 mm (1/4 in.) Be Multi-Pass? Yes No
Leak Test Mthd: Roof* ______Shell* ______Shell Noz./Manhole Reinf. Plt.* ______
Bottom* ______Floating Roof Components* ______
Modify or Waive API Dimensional Tolerances (see 7.5)? No Yes Specify: ______
Specify Additional Tolerances, if any, and Circumferential and Vertical Measurement Locations:
-Allowable Plumbness: ______Measure and Record at a Minimum of ____ Locations or Every ____ m (ft) around the Tank, at the Following Shell Heights: (select one box): 1/3 H, 2/3 H and H Top of Each Shell Course Other: ______
-Allowable Roundness: **______Measure Radius and Record at a Minimum of ______Locations or Every ______m (ft) around the Tank, at the Following Shell Heights (select one box):
Top of Tank, H 1/3 H, 2/3 H and H Top of Each Shell Course Other: ______
**See Data Sheet Instructions for the Maximum Allowable Additional Radial Tolerance.
Approvals: / Revisions: / Title:
By: Ck’d: Date:
Drawing No.: Sheet ___ of ___
API / API Std 650 Storage Tank
Data Sheet / Page 3 of 8
16. Coatings:
Internal Linings by: ______Per Spec.* ______
(Not Req’d., Others, Tank Mfg.)
External Coating by: ______Per Spec.* ______
(Not Req’d., Others, Tank Mfg.)
Under-Bottom Coating by: ______Per Spec.* ______
(Not Req’d., Others, Tank Mfg.)
17. Cathodic Protection System? Yes No Per Spec.* ______
18. Leak Detection System? Yes No Per Spec.*______
19. Release Prevention Barrier? Yes No Per Spec.*______
20. Tank Measurement System: Required? Yes No Remote Capability Required? Yes No
By:* ______Per Spec.* ______
21. Weight of Tank: Full of Water* ______Empty* ______Shipping* ______Brace/Lift Spec.* ______
22. References*: API Std 650, Appendix L
______
______
23. Remarks*:
Approvals: / Revisions: / Title:
By: Ck’d: Date:
Drawing No.: Sheet ___ of ___
API / API Std 650 Storage Tank
Data Sheet / Page 4 of 8
* If box is blank, Manufacturer shall determine and submit as per Appendix L.
Table 1 MATERIALS OF CONSTRUCTION
Component / Material*/Thickness* / C.A. / Component / Material* / C.A.
Shell, Course __ to __ / Reinforcing Pads
Shell, Course __ to __ / Manhole/Nozzle Necks
Shell, Course __ to __ / Manhole/Nozzle Flanges
Shell, Course __ to __ / Flange Covers
Shell, Course __ to __ / Anchor Attachments
Roof / Submerged Piping
Bottom / Wetted Structurals / +
Annular Ring / Non-wetted Structurals / +
+ Check here if C.A. is to apply to each exposed surface .
Table 2 BOLTS and ANCHORS
Component / Head Type* / Bolt or Anchor Material* / Nut Material* / Thread Series* / C.A.
Flange Bolting / ++
Structural Bolting / ++
Anchor Bolts / ++
++ Total C.A., on the nominal diameter.
Table 3 NOZZLE and MANHOLE SCHEDULE* (for Fixed Roof, Shell, and Bottom)
Mark / Service / Size, NPS, or Dia. (In.) / Neck Sch or Wall Thick. / Reinf. Plate Dimensions / Full Pen. On Open. (Y/N) / Flange Type / Flange Class or Thick. / Gasket Bearing Surf. Dimen. and Finish / Gasket Thick. and Dimen. / Gasket Mat’l. and Descript. / Proj. to FF or CL or from Datum Lines
Approvals: / Revisions: / Title:
By: / Ck’d: / Date:
Drawing No.: / Sheet ___ of ___

APPENDIX S— Austenitic Stainless Steel Storage Tanks