1 General Provisions
1.0.1 This code is formulated to standardize design of vertical cylindrical welded steel oil tanks and make it advanced in technology, cost-effective, safe and applicable and high quality.
1.0.2 This code is applicable to design of vertical cylindrical welded steel oil tanks at and close to normal pressure for storing petroleum and petrochemical and other similar liquid but it is not applicable to design of buried tank, tank holding extremely and highly hazardous medium and artificial refrigerant fluid tank.
1.0.3 Design of vertical cylindrical welded steel oil tanks shall comply with not only this code but the current relevant national standards.
2 Terms
2.0.1 Annular/sketch bottom plates
The outermost bottom plates at the lower part of shell plates.
2.0.2 Annular bottom plates
Annular/sketch bottom plates with polygonal or circular inner edge.
2.0.3 Bottom plates
Bottom plates except edge plate.
2.0.4 Fixed roofs
Roof around which shell ends are fixed and connected, mainly including types as follows:
1 Self-supporting cone roof: with circular cone roof and supported only by the shell periphery;
2 Column-supported cone roof: with circular cone roof and supported by shell, girder, column or other structure;
3 Self-supporting dome roof: with spherical roof and supported only by the shell periphery.
2.0.5 Floating roofs
Roof which lifts with the liquid level, including external floating roof, in an open-top oil tank and internal floating roof, in fixed-roof oil tank. Generally the floating roof tank refers to external floating roof tank if not specified. There are major floating roofs as follows:
1 Single-deck floating roof: with annular seal cabin around floating roof and single deck in the middle;
2 Double-deck floating roof: entire floating roof is composed of compartments;
3 Open-top bulk-headed floating roof: with annular open-top compartments around the floating roofs and single deck in the middle and this type is only applicable to internal floating roof;
4 Floating roof on floats: plates keep clear of the liquid level, being floated by the float, only applicable to internal floating roof.
2.0.6 Design pressure
Maximum pressure set at the gas phase room on top of tank (gauge pressure, the same below) shall not be less than the maximum operating pressure likely to be present in normal use.
2.0.7 Metal temperature
Average temperature of shell plates and pressure components along section thickness.
2.0.8 Design temperature
Metal temperature of shell plates and pressure components given under the normal operation of tanks.
2.0.9 Calculated thickness
Thickness obtained by calculation according to the formulae specified in this code.
2.0.10 Design thickness
The sum of calculation thickness and corrosion allowance.
2.0.11 Nominal thickness
Design thickness with tolerance, which is rounded up to standard thickness of materials.
2.0.12 Available thickness
Nominal thickness minus additional thickness
2.0.13 Wind girder
Members arranged on the shell to make it stronger to resist wind.
2.0.14 Stiffening ring
Members arranged on the shell to enhance the stability of tank shell and protect it against instability.
2.0.15 Rolling ladder
Walkway which connects shell roof platform and floating roof and lifts with the floating roof.
2.0.16 Automatic bleeder vent
Venting device which opens/closes automatically when the floating roof rises or is restored to bracing state.
2.0.17 Primary roof drains
Equipment which drains the rainwater on external floating roof out of the tank under normal conditions.
2.0.18 Emergency roof drains
Safety devices which discharge excessive seeper on external floating roof in emergency circumstances.
2.0.19 Circulation vent
Venting device which is arranged on the internal floating roof tank shell or fixed roof in a circular manner.
3 Basic Requirement
3.0.1 For the atmospheric pressure tank at fixed roof, the negative pressure is designed to be 0.25kPa or less and the lifting force generated from positive pressure shall not exceed the total weight of roof plate and the appurtenances thereon; if as specified in Appendix A of this code, the maximum design pressure may be increased to 18kPa; if as specified in Appendix B of this code, the maximum design negative pressure may be increased to 6.9kPa. The atmospheric pressure of floating roof tank is used as the design pressure.
Foreword I
1 General Provisions
2 Terms
3 Basic Requirement
4 Materials
4.1 General Requirement
4.2 Steel Plates
4.3 Steel Pipe
4.4 Forgings
4.5 Screw and Nut
4.6 Structural Steel
4.7 Welding Materials
5 Bottom Design
5.1 Size of Bottom Plates
5.2 Bottom Structure
6 Shell Design
6.1 Shell Plate's Arrangement and Connection
6.2 Curb Angle
6.3 Shell Thickness
6.4 Wind Girder
7 Fixed Roof
7.1 General Requirement
7.2 Allowable Stress of Structural Components
7.3 Self-supporting Cone Roof
7.4 Column-Supported Cone Roof
7.5 Self-supporting Dome Roof
8 Floating Roof
8.1 General Requirement
8.2 Structure and Connection of Floating Roof
8.3 Floating Roof Supports
8.4 Primary Floating Roof Drains
8.5 Emergency Roof Drains
8.6 Rolling Ladder and Track
8.7 Automatic Bleeder Vents
8.8 Guiding Devices
8.9 Peripheral Seals and Static Extracting Devices
8.10 Floating Roof Manhole
8.11 Compartment Manhole
8.12 Wax Scrapers
9 Internal Floating Roof
9.1 General Requirement
9.2 Open-Top Bulk-Headed, Single-Deck and Double-deck Internal Floating Roof
9.3 Internal Floating Roof on Floats
9.4 Internal Floating Roof Supports
9.5 Peripheral Seals
9.6 Automatic Bleeder Vents
9.7 Vents
9.8 High Liquid Level Protection
9.9 Guiding Devices
9.10 Manhole and Inspection Hatches
10 Appurtenances
10.1 General Requirement
10.2 Shell Opening and Reinforcement
10.3 Shell Manholes
10.4 Shell Nozzles
10.5 Flush-type Cleanout Fittings
10.6 Roof Manholes
10.7 Roof Nozzles
10.8 Drain Elbows
10.9 Water Drawoff Sumps
10.10 Spiral Stairway, Platforms and Handrails
10.11 Scaffold Cable Support
10.12 Protection against Lightning, Static and Others
11 Wind Stable Calculation and Anchorage Design of Oil Tanks
11.1 Wind Stable Calculation
11.2 Anchorage Design
12 Prefabrication, Assembling, Welding and Inspection
12.1 Prefabrication, Assembling and Welding
12.2 Non-destructive Testing and Tests of Welding Seam
12.3 Geometry and Dimension Inspection
12.4 Water Filling Test
12.5 Fixed Roof Test
Appendix A Design of Tank for Small Internal Pressures
Appendix B Design of Storage Tank for External Pressure
Appendix C Requirements for Tank Operating at Elevated Temperatures
Appendix D Seismic Design of Oil Tank
Appendix E Basic Requirement of Foundation and Basis for Oil Tank
Appendix F Load Combinations
Appendix G Variable-design-point Method on Tank Shell Thickness Calculation
Appendix H Calculation for Spherical Dome Roof with Rib Reinforcement
Appendix J Allowable External Loads on Shell Openings
Explanation of Wording in This Code
List of Quoted Standards
