Flare Header Design

[Timewrap]

Dear Experts,

I want your comments on the flare header design, If I knew the total flare load and the all the information about installed PSV's. Can I assume that total allowable backpressure in the header from the PSV outlet flange to the flare tip should not not be more the 10 % of the set pressure of the lowest PSV in the system.

What are other considerations??

Timewrap

 

[Unotec]

Take a tour through The Flareman:

http://www.geocities.com/flareman_xs/

It has helped me a lot


<<A good friend will bail you out of jail, but a true friend
will be sitting beside you saying ” Damn that was fun!” - Unknown>>

 

[Flareman]

Timewrap
The maximum flare header pressure under any given flow condition depends mainly on the type of relief valve you are using and the conditions which apply to its design.
You need to check with the valve supplier(s) or data sheets. Sometimes a valve can be "balanced" so that it can tolerate a high back pressure and still be expected to pass the design flow. Others, which are simple orifices are sized on the basis that the downstream pressure is low AND that the upstream pressure is allowed to build above the setpoint.
I would suggest that you read through API std 521/ISO 23251 and RP-526.
Frequently, using the 10% downstream value is a short-cut solution to save you having to do the basic research but it can cause you to oversize headers in some cases. It all comes down to economics in the end.

[BTW Unotec, thanks for the good word, however I think you overstate the extent of the valuable information. It just puts me under more pressure to update things. Oh bother!!]

David

 

[Timewrap]

Dear All,

Thanks to you all for your valuable comments.

Timewrap.