API Standard 650 Welded Tanks for Oil Storage

This Standard is based on the accumulated knowledge and experience of Purchasers and Manufacturers of welded oil storage tanks of various sizes and capacities for internal pressures not more than 17.2 kPa (21/2 pounds per square inch) gauge. This Standard is meant to be a purchase specification to facilitate the manufacture and procurement of storage tanks for the petroleum industry. If the tanks are purchased in accordance with this Standard, the Purchaser is required to specify certain basic requirements. The Purchaser may want to modify, delete, or amplify sections of this Standard, but reference to this Standard shall not be made on the nameplates of or on the Manufacturer’s certification for tanks that do not fulfill the minimum requirements of this Standard or that exceed its limitations. It is strongly recommended that any modifications, deletions, or amplifications be made by supplementing this Standard rather than by rewriting or incorporating sections of it into another complete standard. The design rules given in this Standard are minimum requirements. More stringent design rules specified by the Purchaser or furnished by the Manufacturer are acceptable when mutually agreed upon by the Purchaser and the Manufacturer. This Standard is not to be interpreted as approving, recommending, or endorsing any specific design or as limiting the method of design or construction. The verbal forms used to express the provisions in this document are as follows. Shall: As used in a standard, “shall” denotes a minimum requirement in order to conform to the standard. Should: As used in a standard, “should” denotes a recommendation or that which is advised but not required in order to conform to the standard. May: As used in a standard, “may” denotes a course of action permissible within the limits of a standard. Can: As used in a standard, “can” denotes a statement of possibility or capability. Cover Figures Figure 4.1a—Minimum Permissible Design Metal Temperature for Materials Used in Tank Shells withoutImpact Testing (SI) Figure 4.1b—Minimum Permissible Design Metal Temperature for Materials Used in Tank Shells withoutImpact Testing (USC) Figure 4.2—Isothermal Lines of Lowest One-Day Mean Temperatures (°F) Figure 4.3—Governing Thickness for Impact Test Determination of Shell Nozzle andManhole Materials Figure 5.1—Typical Vertical Shell Joints Figure 5.2—Typical Horizontal Shell Joints Figure 5.3a—Typical Roof and Bottom Joints Figure 5.3b—Method for Preparing Lap-welded Bottom Plates under Tank Shell Figure 5.3c—Detail of Double Fillet-groove Weld for Annular Bottom Plates with a Nominal ThicknessGreater than 13 mm (1/2 in.) Figure 5.3d—Spacing of Three-Plate Welds at Annular Plates Figure 5.4—Storage Tank Figure 5.5—Drip Ring (Suggested Detail) Figure 5.6—Minimum Weld Requirements for Openings in Shells According to 5.7.3 Figure 5.7a—Shell Manhole Figure 5.7b—Details of Shell Manholes and Nozzles Figure 5.8—Shell Nozzles (see Tables 5.6a, 5.6b, 5.7a, 5.7b, 5.8a, and 5.8b) Figure 5.9—Minimum Spacing of Welds and Extent of Related Radiographic Examination Figure 5.10—Shell Nozzle Flanges (see Table 5.8a and Table 5.8b) Figure 5.11—Area Coefficient for Determining Minimum Reinforcement of Flush-type Cleanout Fittings Figure 5.12—Flush-Type Cleanout Fittings (see Tables 5.9a, 5.9b, 5.10a, 5.10b, 5.11a, and 5.11b) Figure 5.13—Flush-type Cleanout Fitting Supports (see 5.7.7) Figure 5.14—Flush-type Shell Connection Figure 5.15—Rotation of Shell Connection Figure 5.16—Roof Manholes (see Table 5.13a and Table 5.13b) Figure 5.17—Rectangular Roof Openings with Flanged Covers Figure 5.18—Rectangular Roof Openings with Hinged Cover Figure 5.19—Flanged Roof Nozzles (see Table 5.14a and Table 5.14b) Figure 5.20—Threaded Roof Nozzles (see Table 5.15a and Table 5.15b) Figure 5.21—Drawoff Sump (see Table 5.16a and Table 5.16b) Figure 5.22—Scaffold Cable Support Figure 5.23—Grounding Lug Figure 5.24—Typical Stiffening-ring Sections for Tank Shells (see Table 5.19a and Table 5.19b) Figure 5.25—Stairway Opening through Stiffening Ring Figure 5.26—Some Acceptable Column Base Details Figure 5.27—Overturning Check for Self-anchored Tanks Figure 5.28—Typical Anchor Chair Figure 5.29—Typical Anchor Strap Welded Attachment (for Carbon Steel Tank) Figure 5.30—Typical Hold-down Strap Configuration (for Carbon Steel Tank) Figure 5.31—Butt Weld Joint with Back-up Bar Figure 6.1—Shaping of Plates Figure 8.1—Radiographic Requirements for Tank Shells Figure 10.1—Manufacturer’s Nameplate Figure 10.2—Manufacturer’s Certification Letter Figure AL.1—Cover Plate Thickness for Shell Manholes and Cleanout Fittings Figure AL.2—Flange Plate Thickness for Shell Manholes and Cleanout Fittings Figure AL.3—Bottom Reinforcing Plate Thickness for Cleanout Fittings Figure AL.4—Stresses in Roof Plates Figure B.1—Example of Foundation with Concrete Ringwall Figure B.2—Example of Foundation with Crushed Stone Ringwall Figure E.1—Coefficient Ci Figure EC.1—Maximum Earthquake Response Spectrum Figure EC.2—Earthquake Response Spectrum Notation Figure EC.3—Site Specific Response Spectrum Figure EC.4—Deterministic Lower Limit on MCE Response Spectrum Figure EC.5—Relationship of Probabilistic and Deterministic Response Spectra Figure EC.6—Sloshing Factor, Ks Figure EC.7—Design Response Spectra for Ground-Supported Liquid Storage Tanks Figure EC.8—Effective Weight of Liquid Ratio Figure EC.9—Center of Action of Effective Forces Figure EC.10—Overturning Moment Figure F.1—Annex F Decision Tree Figure F.2—Permissible Details of Compression Rings Figure G.1—Data Sheet for a Structurally-Supported Aluminum Dome Added to an Existing Tank Figure G.2—Typical Roof Nozzle Figure I.1—Concrete Ringwall with Undertank Leak Detection at the Tank Perimeter (Typical Arrangement) Figure I.2—Crushed Stone Ringwall with Undertank Leak Detectionat the Tank Perimeter (Typical Arrangement) Figure I.3—Earthen Foundation with Undertank Leak Detection at the Tank Perimeter (Typical Arrangement) Figure I.4—Double Steel Bottom with Leak Detection at the Tank Perimeter (Typical Arrangement) Figure I.5—Double Steel Bottom with Leak Detection at the Tank Perimeter (Typical Arrangement) Figure I.6—Reinforced Concrete Slab with Leak Detection at the Perimeter (Typical Arrangement) Figure I.7—Reinforced Concrete Slab Figure I.8—Typical Drawoff Sump Figure I.9—Center Sump for Downward-Sloped Bottom Figure I.10—Typical Leak Detection Wells Figure I.11—Tanks Supported by Grillage Members (General Arrangement) Figure O.1—Example of Under-Bottom Connection with Concrete Ringwall Foundation Figure O.2—Example of Under-Bottom Connection with Concrete Ringwall Foundation and Improved TankBottom and Shell Support Figure O.3—Example of Under-Bottom Connection with Earth-Type Foundation Figure P.1—Nomenclature for Piping Loads and Deformation Figure P.2a—Stiffness Coefficient for Radial Load: Reinforcement on Shell (L/2a = 1.0) Figure P.2b—Stiffness Coefficient for Longitudinal Moment: Reinforcement on Shell (L/2a = 1.0) Figure P.2c—Stiffness Coefficient for Circumferential Moment: Reinforcement on Shell (L/2a = 1.0) Figure P.2d—Stiffness Coefficient for Radial Load: Reinforcement on Shell (L/2a = 1.5) Figure P.2e—Stiffness Coefficient for Longitudinal Moment: Reinforcement on Shell (L/2a = 1.5) Figure P.2f—Stiffness Coefficient for Circumferential Moment: Reinforcement on Shell (L/2a = 1.5) Figure P.2g—Stiffness Coefficient for Radial Load: Reinforcement in Nozzle Neck Only (L/2a = 1.0) Figure P.2h—Stiffness Coefficient for Longitudinal Moment: Reinforcement in Nozzle Neck Only (L/2a = 1.0) Figure P.2i—Stiffness Coefficient for Circumferential Moment: Reinforcement in Nozzle Neck Only (L/2a = 1.0) Figure P.2j—Stiffness Coefficient for Radial Load: Reinforcement in Nozzle Neck Only (L/2a = 1.5) Figure P.2k—Stiffness Coefficient for Longitudinal Moment: Reinforcement in Nozzle Neck Only (L/2a = 1.5) Figure P.2l—Stiffness Coefficient for Circumferential Moment: Reinforcement in Nozzle Neck Only (L/2a = 1.5) Figure P.3a—Construction of Nomogram for b1, b2, c1, c2 Boundary Figure P.3b—Construction of Nomogram for b1, c3 Boundary Figure P.4a—Obtaining Coefficients YF and YL Figure P.4b—Obtaining Coefficient YC Figure P.5a—Determination of Allowable Loads from Nomogram: FR and ML Figure P.5b—Determination of Allowable Loads from Nomogram: FR and MC Figure P.6—Low-type Nozzle with Reinforcement on Shell Figure P.7—Allowable-load Nomograms for Sample Problem Figure V.1a—Dimensions for Self-Supporting Cone Roof Figure V.1b—Dimensions for Self-Supporting Dome Roof Tables Table 4.1—Maximum Permissible Alloy Content Table 4.2—Acceptable Grades of Plate Material Produced to National Standards (See 4.2.6) Table 4.3a—Linear Equations for 4.1a (SI) Table 4.3b—Linear Equations for 4.1b (USC) Table 4.4a—Material Groups (SI) Table 4.4b—Material Groups (USC) Table 4.5a—Minimum Impact Test Requirements for Plates (SI) (See Note) Table 4.5b—Minimum Impact Test Requirements for Plates (USC) (See Note) Table 5.1a—Annular Bottom-Plate Thicknesses (tb) (SI) Table 5.1b—Annular Bottom-Plate Thicknesses (tb) (USC) Table 5.2a—Permissible Plate Materials and Allowable Stresses (SI) Table 5.2b—Permissible Plate Materials and Allowable Stresses (USC) Table 5.3a—Thickness of Shell Manhole Cover Plate and Bolting Flange (SI) Table 5.3b—Thickness of Shell Manhole Cover Plate and Bolting Flange (USC) Table 5.4a—Dimensions for Shell Manhole Neck Thickness (SI) Table 5.4b—Dimensions for Shell Manhole Neck Thickness (USC) Table 5.5a—Dimensions for Bolt Circle Diameter Db and Cover Plate Diameter Dc for Shell Manholes (SI) Table 5.5b—Dimensions for Bolt Circle Diameter Db and Cover Plate Diameter Dc for Shell Manholes (USC) Table 5.6a—Dimensions for Shell Nozzles (SI) Table 5.6b—Dimensions for Shell Nozzles (USC) Table 5.7a—Dimensions for Shell Nozzles: Pipe, Plate, and Welding Schedules (SI) Table 5.7b—Dimensions for Shell Nozzles: Pipe, Plate, and Welding Schedules (USC) Table 5.8a—Dimensions for Shell Nozzle Flanges (SI) Table 5.8b—Dimensions for Shell Nozzle Flanges (USC) Table 5.9a—Dimensions for Flush-type Cleanout Fittings (SI) Table 5.9b—Dimensions for Flush-type Cleanout Fittings (USC) Table 5.10a—Minimum Thickness of Cover Plate, Bolting Flange, and Bottom Reinforcing Plate for Flush-typeCleanout Fittingsf (SI) Table 5.10b—Minimum Thickness of Cover Plate, Bolting Flange, and Bottom Reinforcing Plate forFlush-type Cleanout Fittingsf (USC) Table 5.11a—Thicknesses and Heights of Shell Reinforcing Plates for Flush-type Cleanout Fittings (SI) Table 5.11b—Thicknesses and Heights of Shell Reinforcing Plates for Flush-type Cleanout Fittings (USC) Table 5.12a—Dimensions for Flush-type Shell Connections (SI) Table 5.12b—Dimensions for Flush-type Shell Connections (USC) Table 5.13a—Dimensions for Roof Manholes (SI) Table 5.13b—Dimensions for Roof Manholes (USC) Table 5.14a—Dimensions for Flanged Roof Nozzles (SI) Table 5.14b—Dimensions for Flanged Roof Nozzles (USC) Table 5.15a—Dimensions for Threaded Roof Nozzles (SI) Table 5.15b—Dimensions for Threaded Roof Nozzles (USC) Figure 5.19—Flanged Roof Nozzles (see Table 5.14a and Table 5.14b) Figure 5.20—Threaded Roof Nozzles (see Table 5.15a and Table 5.15b) Table 5.16a—Dimensions for Drawoff Sumps (SI) Table 5.16b—Dimensions for Drawoff Sumps (USC) Table 5.17—Requirements for Platforms and Walkways Table 5.18—Requirements for Stairways Table 5.19a—Section Moduli (cm3) of Stiffening-Ring Sections on Tank Shells (SI) Table 5.19b—Section Moduli (in.3) of Stiffening-Ring Sections on Tank Shells (USC) Table 5.20a—Uplift Loads (SI) Table 5.20b—Uplift Loads (USC) Table 5.21—Unfactored (Working Stress) Downward Reactions on Foundations Table 7.1a—Minimum Preheat Temperatures (SI) Table 7.1b—Minimum Preheat Temperatures (USC) Table A.1a—Typical Sizes and Corresponding Nominal Capacities (m3) for Tanks with 1800-mm Courses (SI) Table A.1b—Typical Sizes and Corresponding Nominal Capacities (Barrels) for Tanks with 72-in. Courses (USC) Table A.2a—Typical Sizes and Corresponding Nominal Capacities (m3) for Tanks with 2400-mm Courses (SI) Table A.2b—Typical Sizes and Corresponding Nominal Capacities (Barrels) for Tanks with 96-in. Courses (USC) Table AL.1—Material Specifications Table AL.2—Joint Efficiency Table AL.3a—Minimum Mechanical Properties (SI) Table AL.3b—Minimum Mechanical Properties (USC) Table AL.4a—Annular Bottom Plate Thickness (SI) Table AL.4b—Annular Bottom Plate Thickness (USC) Table AL.5a—Minimum Shell Thickness (SI) Table AL.5b—Minimum Shell Thickness (USC) Table AL.6a—Allowable Tensile Stresses for Tank Shell (for Design and Test) (SI) Table AL.6b—Allowable Tensile Stresses for Tank Shell (for Design and Test) (USC) Table AL.7a—Allowable Stresses for Roof Plates (SI) Table AL.7b—Allowable Stresses for Roof Plates (USC) Table AL.8a—Compressive Moduli of Elasticity E (MPa) at Temperature C) (SI) Table AL.8b—Compressive Moduli of Elasticity E (ksi) at Temperature (F) (USC) Table AL.9a—Shell Nozzle Welding Schedule (SI) Table AL.9b—Shell Nozzle Welding Schedule (USC) Table E.1—Value of Fa as a Function of Site Class Table E.2—Value of Fv as a Function of Site Class Table E.3—Site Classification Table E.4—Response Modification Factors for ASD Methods Table E.5—Importance Factor (I) and Seismic Use Group Classification Table E.6—Anchorage Ratio Criteria Table E.7—Minimum Required Freeboard Table E.8—Design Displacements for Piping Attachments Table J.1a—Minimum Roof Depths for Shop-assembled Dome-roof Tanks (SI) Table J.1b—Minimum Roof Depths for Shop-assembled Dome-roof Tanks (USC) Table K.1a—Shell-Plate Thicknesses Based on the Variable-design-point Method (See 5.6.4) Using 2400-mm Courses and an Allowable Stress of 159 MPa for the Test Condition (SI) Table K.1b—Shell-Plate Thicknesses Based on the Variable-design-point Method (See 5.6.4) Using 96-in. Courses and an Allowable Stress of 23,000 lbf/in.2 for the Test Condition (USC) Table K.2a—Shell-Plate Thicknesses Based on the Variable-design-point Method (See 5.6.4) Using 2400-mm Courses and an Allowable Stress of 208 MPa for the Test Condition (SI) Table K.2b—Shell-Plate Thicknesses Based on the Variable-design-point Method (See 5.6.4) Using 96-in. Courses and an Allowable Stress of 30,000 lbf/in.2 for the Test Condition (USC) Table K.3a—Shell-Plate Thicknesses Based on the Variable-design-point Method (See 5.6.4) Using 2400-mm Courses and an Allowable Stress of 236 MPa for the Test Condition (SI) Table K.3b—Shell-Plate Thicknesses Based on the Variable-design-point Method (See 5.6.4) Using 96-in. Courses and an Allowable Stress of 34,300 lbf/in.2 for the Test Condition (USC) Table L.1—Index of Decisions or Actions That May be Required of the Tank Purchaser Table M.1a—Yield Strength Reduction Factors (SI) Table M.1b—Yield Strength Reduction Factors (USC) Table M.2a—Modulus of Elasticity at the Maximum Design Temperature (SI) Table M.2b—Modulus of Elasticity at the Maximum Design Temperature (USC) Table O.1a—Dimensions of Under-Bottom Connections (SI) Table O.1b—Dimensions of Under-Bottom Connections (USC) Table P.1a—Modulus of Elasticity and Thermal Expansion Coefficient at the Design Temperature (SI) Table P.1b—Modulus of Elasticity and Thermal Expansion Coefficient at the Design Temperature (USC) Table S.1a—ASTM Materials for Stainless Steel Components (SI) Table S.1b—ASTM Materials for Stainless Steel Components (USC) Table S.2a—Allowable Stresses for Tank Shells (SI) Table S.2b—Allowable Stresses for Tank Shells (USC) Table S.3a—Allowable Stresses for Plate Ring Flanges (SI) Table S.3b—Allowable Stresses for Plate Ring Flanges (USC) Table S.4—Joint Efficiencies Table S.5a—Yield Strength Values in MPa (SI) Table S.5b—Yield Strength Values in psi (USC) Table S.6a—Modulus of Elasticity at the Maximum Design Temperature (SI) Table S.6b—Modulus of Elasticity at the Maximum Design Temperature (USC) Table U.1a—Flaw Acceptance Criteria for UT Indications May be Used for All Materials (SI) Table U.1b—Flaw Acceptance Criteria for UT Indications May be Used for All Materials (USC) Table X.1—ASTM Materials for Duplex Stainless Steel Components Table X.2a—Allowable Stresses for Tank Shells (SI) Table X.2b—Allowable Stresses for Tank Shells (USC) Table X.3—Joint Efficiencies Table X.4a—Yield Strength Values in MPa Table X.4b—Yield Strength Values in PSI Table X.5a—Modulus of Elasticity at the Maximum Design Temperature (SI) Table X.5b—Modulus of Elasticity at the Maximum Design Temperature (USC) Table X.6a—Hot Forming Temperatures (SI) Table X.6b—Hot Forming Temperatures (USC) Special Notes Instructions for Submitting a Proposed Revision to this Standard Under ContinuousMaintenance Foreword Important Information Concerning Use of Asbestos or Alternative Materials Table of Contents SECTION 1—SCOPE 1.1 General 1.2 Limitations 1.3 Responsibilities 1.4 Documentation Requirements 1.5 Formulas SECTION 2—NORMATIVE REFERENCES SECTION 3—TERMS AND DEFINITIONS SECTION 4—MATERIALS 4.1 General 4.2 Plates 4.3 Sheets 4.4 Structural Shapes 4.5 Piping and Forgings 4.6 Flanges 4.7 Bolting 4.8 Welding Electrodes 4.9 Gaskets SECTION 5—DESIGN 5.1 Joints 5.2 Design Considerations 5.3 Special Considerations 5.4 Bottom Plates 5.5 Annular Bottom Plates 5.6 Shell Design 5.7 Shell Openings 5.8 Shell Attachments and Tank Appurtenances 5.9 Top and Intermediate Stiffening Rings (Wind Girders) 5.10 Roofs 5.11 Wind Load on Tanks (Overturning Stability) 5.12 Tank Anchorage 5.13 Downward Reactions on Foundations SECTION 6—FABRICATION 6.1 General 6.2 Shop Inspection SECTION 7—ERECTION 7.1 General 7.2 Details of Welding 7.3 Examination, Inspection, and Repairs 7.4 Repairs to Welds 7.5 Dimensional Tolerances SECTION 8—METHODS OF EXAMINING JOINTS 8.1 Radiographic Method 8.2 Magnetic Particle Examination 8.3 Ultrasonic Examination 8.4 Liquid Penetrant Examination 8.5 Visual Examination 8.6 Vacuum Testing SECTION 9—WELDING PROCEDURE AND WELDER QUALIFICATIONS 9.1 Definitions 9.2 Qualification of Welding Procedures 9.3 Qualification of Welders 9.4 Identification of Welded Joints SECTION 10—MARKING 10.1 Nameplates 10.2 Division of Responsibility 10.3 Certification Annex A (normative) Optional Design Basis for Small Tanks Annex AL (normative) Aluminum Storage Tanks Annex B (informative) Recommendations for Design and Construction of Foundations forAboveground Oil Storage Tanks Annex C (normative) External Floating Roofs Annex D (informative) Inquiries and Suggestions for Change Annex E (normative) Seismic Design of Storage Tanks Annex EC (informative) Commentary on Annex E Annex F (normative) Design of Tanks for Small Internal Pressures Annex G (normative) Structurally-Supported Aluminum Dome Roofs Annex H (normative) Internal Floating Roofs Annex I (normative) Undertank Leak Detection and Subgrade Protection Annex J (normative) Shop-Assembled Storage Tanks Annex K (informative) Sample Applications of the Variable-Design-Point Method to DetermineShell-Plate Thickness Annex L (normative) API Standard 650 Storage Tank Data Sheet Annex M (normative) Requirements for Tanks Operating at Elevated Temperatures Annex N (normative) Use of New Materials That Are Not Identified Annex O (normative) Under-Bottom Connections Annex P (normative) Allowable External Loads on Tank Shell Openings Annex R (informative) References for Tanks in Non-petroleum Product Service Annex S (normative) Austenitic Stainless Steel Storage Tanks Annex SC (normative) Stainless and Carbon Steel Mixed Materials Storage Tanks Annex T (informative) NDE Requirements Summary Annex U (normative) Ultrasonic Examination in Lieu of Radiography Annex V (normative) Design of Storage Tanks for External Pressure Annex W (normative) Commercial and Documentation Recommendations Annex X (normative) Duplex Stainless Steel Storage Tanks Annex Y (informative) API Monogram ProgramUse of the API Monogram by Licensees Bibliography