How to limit evaporation of liquid contents from API standard 650 ground supported flat-bottom tanks

The specifications used in the design of large oil tanks, API standard 650 ground supported flat-bottom tanks mainly include American Petroleum Institute Standard API 650, Japanese Industrial Standard JIS B8501, British Industrial Standard BS2654 and Chinese National Standard GB50341 from a global perspective. The formulas used in each specification are based on the hoop stress in the membrane theory. Each specification is based on the performance characteristics of materials and the construction technology level of their respective countries to determine the allowable stresses and weld coefficients. Therefore, the calculation results of tank wall thickness of API standard 650 ground supported flat-bottom tanks with the same volume are sometimes quite different according to different specifications.

Facilities for API 620 storage tanks InspectorThe manufacturer shall afford the inspector all reasonable facilities for testing and inspection and shall provide mutually agreeable advance notification to permit the examiner to witness all tests of the equipment and materials during fabrication, including all laboratory tests of the material to be used and all hydrostatic and pneumatic tests at the site of erection.The API standard 650 ground supported flat-bottom tanks inspector shall be permitted free access to all parts of the plant concerned with the manufacture of the tank during fabrication and to all parts of the plants of material suppliers who are concerned with the manufacture of materials to be used in the tank.

In Appendix E to API 650 oil storage tank, the maximum values of inertia force, pulse pressure and convection pressure are superimposed, and tend to be conservative.In GB50341, only pulse pressure is calculated for API standard 650 ground supported flat-bottom tanks tanks below 5000 m.