Design vacuum pressure for API 620 tanks

[gofish123]

API 650, Appendix V, provides the normal operating external pressure range as 0.25 kPa (0.036 lbf/in2) to 6.9 kPa (1.0 lbf/in2). I understand API 620 tanks stipulates the maximum partial vacuum to be at least 1 in. wc. Is there an upper limit too on the design vacuum pressure for API 620 tanks?

 

[JStephen]

API-620 just doesn't address vacuum design.

In general, for a tank configured like an API-650 tank, the rules from API-650 could be applied to evaluate for vacuum loads if needed.