API 650 ground supported tanks shell rings

Inspection of weld and micro crack of API 650 ground supported tanks: the inner and outer surface of API 650 ground supported tanks, weld and heat affected zone shall be observed by naked eyes first. 100% ultrasonic testing or 100% penetrant testing are carried out for butt welds of API 650 ground supported tanks. For the defects found by 100% magnetic particle inspection, dye detection, 100% ultrasonic inspection or 100% penetrant inspection, the radiographic inspection shall be used again to ensure the accuracy of the test results.

Soil Structure Interaction: Soil structure interaction per API 650, Section E.6.1.6 may be used for OLE design providing the damping ratio does not exceed 10 %.
Allowable Stresses
Design allowable stresses shall be per API 620 large welded steel storage tank, Section Q.3.3, including the 33 % increase permitted for earthquake loads.
Self-anchored Inner Tank
The anchorage ratio for a self-anchored inner tank, J, shall not exceed 1.0 for the OLE design combination to limit uplift and stresses in the annular plate and corner weld.
Foundation Stability
The overturning ratio defined in API 650, Section E.6.2.3, Equation (E.6.2.3-1) shall be equal to or greater than 3.0 for the defined OLE event.

This specification, in conjunction with API 650 Standard, prescribes minimum standards for the API 650 ground supported tanks design, supply, fabrication, erection, and testing of field erected welded steel storage tanks complete with accessories as specified herein and as shown on attached Datasheets and/or Drawings.