For Gate valve,150 rating, pneumatic test with API598 and piping system pneumatic test at site

[ANTRIJ]

For flanged Gate valve,150 rating for nitrogen purging , manufacture has done valve test with air as per API598 with 7kg/cm2g w.r.t bid data sheet ,there is no leakages found .However it is noticed,there is leak in valve,with pneumatic test at 13.2 Kg/cm2 (g) at site (pressure as per process line list) as per TPI(Third Party Inspection).I would like to know ,for piping system pneumatic testing to be done including valve or not.Is there any mistake in process line list for medium and test pressure.

Your help would be highly appreciated.
Thanks in advance.

 

[mk3223]

Typically, the block valve is tested together with the piping to ensure the integrity of the system.
Even the Manufacturer claimed that the valve passed the leak test at 7kg/cm2 per API598, the Class 150 valve should be good up to the 20 kg/cm2 operation pressure without a leak. Right?!

 

[ANTRIJ]

Thank you for your responses

 

[SJones]

Why not ask in the Piping & Pipelines Engineering forum. After all, there isn't much metallurgy in the question.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.