API 650 low-alloy steel tanks bottom-reinforcing plate

The factors that affect the "small breathing" loss of API 650 low-alloy steel tanks are: 1. Generally, the larger the storage tank is, the larger the total open area is, the larger the evaporation area is, and the greater the "small breathing" loss is; conversely, the smaller the storage tank is, the smaller the evaporation area is and the smaller the "small breathing" loss is. 2. It is related to the atmosphere. The lower the atmospheric pressure is, the greater the "small breathing" loss is; otherwise, the loss is reduced.

Storage Tank Annular Bottom Plates
Thickness shall be per API 650, Appendix E (with loads modified by requirements of this appendix) plus corrosion allowance unless a thickness increase is required for compliance with Appendix R or Appendix Q. Annular plate width shall be per API 650, Appendix E (with loads modified by requirements of this appendix) unless a width increase is required for compliance with Appendix R or Appendix Q. Thickness used for determination of API 650 welded storage tank standard, Appendix E width shall be based on the thickness required for seismic product hold down.

Before pressure testing, thoroughly flush the API 650 tank floating roof primary drain hose system. Supply API 650 low-alloy steel tanks blind flanges, gaskets, and bolting (for other types of blanking covers as may be required) necessary for testing.