acceptable flange usage

[augustabound]

Would like some input. We have an engineer who has, due to a machining error on a threaded hole for some electrical feedthru on a 1500# RF flange, decided to turn the flange around and us the normally atmosphere exposed side to mate with the companion RF flange. His assumption is that it will work like a FF flange. This is on a code certified pressure vessel. Expected temp range is 200 C at 600 psi mineral oil.

Comments on this practice would be appreciated.

 

[unclesyd]

Normally the backside of a flange is not smooth enough to do as you state, which isn't the best idea to start with.
Normally you can cleanup the backside and relieve the flange to configure it as a raised faced flange and use it as a normal flange. With your conditions there should be problem.

You should document, evaluate using the flange in the reverse with the new dimensions, after reworking of the flange.