Self Secure Design

I’m currently writing a relief valve philosophy (which includes pressure reliefing systems, emergency depressurisation and disposal systems) for a refinery. The refinery now wants to include a chapter about self secure design. I couldn’t find that term in API 521 and related documents.

  1. As far as I understand it, self secure design means a column has a maximum operating pressure which is high enough to cope with every relief requirement without reliefing. Is that correct?
  2. Is there any standard which regulates the use of this design?

In particular, API 521 states that the relief contingency that produces the greatest back pressure should be identified for the design of common header systems and manifolds in multiple-device installations. It also states that in certain scenarios it can be appropriate to assume some level of favorable instrument and/or operation response (API 521,
The refinery now wants to assume favorable operation response for there so called “self secure design”. I have never ever heard about this term. I just want to make sure, the refinery sticks with the standard.
Has anybody heard anything about “self secure design” and whether it is appropriate to assume it as favorable operation response?


I believe they mean “overpressure protection by system design?” See ASME Sec VIII Div I, UG-140.

Above is a snippet.