Relief valve close system - again

Maybe this query is already brought up before.

Please drop the link if you happen to encounter the same subject.


•If you notice, that in the design temperatures given by process, there is always a big difference with the inlet design temperature and outlet design temperature. Sometimes,
the outlet line that goes to the Flare headers is 10x fold from the inlet design.

Every project that i have worked may differ in their intructions.

Is there anyway to resolve this issue in stress analysis?
Can we have a uniform way of analyzing the system?

Please share some of your views. Thanks.

Many times, the process engineers will take the main header design temperature and will assign to all the lines downstream the PSV regardsless the design temperature of the lines upstream PSV. The nature of gases is that after PSV the temperature will drop because of gas expansion. Some will say that if the main header is designed for fire condition (somewhere at 400C) and if this temperature is real then all the branches will see this temperature. Well....maybe a small part, let say 1000 mm (for convenience).

Since the design temperature is not the same with flexibility temperature, you may want to take advantage of this, regardless the "official" design temperature. So as a minimum you should take the upstream temperature for part of the downstream line, then for the last meter the header temperature.

Do not forget to have a operating scenario with upstream lines hot, downstream lines cold (as this is normal operating mode)

Regards,

Gratitude.

I could really accept this idea.

Don't forget to obtain the approval before you do this.

jajaja...yes sure. ü

Would be nice if others can share there thoughts also.
This is the reason why I posted this problem in order
to gather different opinions, facts and could make a kind of generalization
about relief system analysis.

It may sound simple and very basic to discuss on this for others, but
i only find it interesting because during the past projects involved,
they always have different pathforwards. I want only to investigate
what are the best way to analyze and have a best reason
when talking to process people.
_________________________
if we can do as what Dan mentioned from the previous post
•we can minimize the time of analyzing this kind of systems
•we can minimize the additional piping flexibilities which we always requested from the Design team.
etc.

Have you noticed that there are no more big names in this forum? (except of course the moderators and few respectfull members) So this is why i'm here to offer to those interested my small experience.

Regards,

Or to be more expresive: when there are no T-Rex, Velociraptors came into play.

Regards,

LOL ...you are very humble.

But its good that you are here to keep on sharing your knowledge.

thanks.

yes by the way, i notice that this forum is not the same as before.
is it because all the topics were already discussed?
I hope that this community will get busy again.