Stored Energy in Pneumatic Pressure Test

[PeveLNG]

Hi everyone,

I'm joining the team now with, I hope, an interesting question:
Is there a real limit for stored energy during pneumatic pressure test?
I'm dealing in these days with the Client, in France, in a LNG terminal Receiving.
EN Codes are far from a real answer and obviously we're using, as reference, the good and always actual ASME PCC-2.
May I have a suggestion?

 

[Duwe6]

We had a lively discussion recently:

http://www.eng-tips.com/viewthread.cfm?qid=358563

To address your specific concern; nope, no 'limit' to stored energy. Use the 'Good Engineering Practices' delineated in the post to control the risk. And when you designate your exclusion zone, have it patroled. There is always some idiot that thinks that your piddly test is nothing for him/her to respect. And spend as little time at 'overload' as necessary. ASME says '10-minutes', then reduce pressure and closely inspect the item. On my tests, 10-minutes goes pretty fast [if it made it 30-40 seconds, the remaining 9 minutes seems a little unnecessary]. Once the pressure has been dropped down towards Design, from the full test pressure, you are in 'safe territory' and can reasonably assume that your item has proven itself to be safe. Start checking for pinhole leaks, and allow everybody back into the area.

 

[PeveLNG]

Thanks Duwe6,

I did, at least 500-600 pneu test and I know the risk involved.
I'm just looking for answers regarding the limit...
On my last job I was permitted to reach 862 MJoules, not bad eh?
Following ASME PCC-2, now, with that limit, the safety distance is set about 120 meters....
My client insists that the max shall be 135,5 MJoules...

 

[Duwe6]

And they arrived at that number how?? 10MJ in a 'cheezy' vessel is a LOT riskier than 800MJ in an ASME vessel with Full Radiography. Arbitrary limits are just that -- arbitrary.