Pneumatic test o hydrostatic one for a Tie-In??
Pneumatic test o hydrostatic one for a Tie-In??
(OP)
Hi,
We are going to provide Tie-In (cold cut) presure test for a gas treating plant. We find a doubt concerning the hydrotest to apply over this Tie-In because pipes downstream we find are very long headers and it would take us too much time to test them. Would be possible and safe to apply a pneumatic test due to ASME 31.1 and ASME 31.4?. Would be possible just to do the hydrotest over the Tie-In (only including the blind, spectacle, gate vale and split tee) without doing the hole (without extraction the coupon) and then consider the complete line downstream chequed?
Thanks
We are going to provide Tie-In (cold cut) presure test for a gas treating plant. We find a doubt concerning the hydrotest to apply over this Tie-In because pipes downstream we find are very long headers and it would take us too much time to test them. Would be possible and safe to apply a pneumatic test due to ASME 31.1 and ASME 31.4?. Would be possible just to do the hydrotest over the Tie-In (only including the blind, spectacle, gate vale and split tee) without doing the hole (without extraction the coupon) and then consider the complete line downstream chequed?
Thanks





RE: Pneumatic test o hydrostatic one for a Tie-In??
After performing 100% Rx to the field welds I would say yes.
RE: Pneumatic test o hydrostatic one for a Tie-In??
The key is to document your welding procedure, the welder's certification test papers, the NDT required, and all test results in your permanant project files.
David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
The harder I work, the luckier I seem
RE: Pneumatic test o hydrostatic one for a Tie-In??
Patricia Lougheed
Please see FAQ731-376 for tips on how to make the best use of the Eng-Tips Forums.
RE: Pneumatic test o hydrostatic one for a Tie-In??
It depends on the code that covers your installation. Here’s what the federal code says about natural gas pipelines. It seems to fit your situation (I think the same applies to oil pipelines). As far as I know, the strength test only applies to pipe; not welds. Welds are required to be NDT.
Title 49: PART 192.505 Strength test requirements for steel pipeline to operate at a hoop stress of 30 percent or more of SMYS.
……
……
(e) For fabricated units and short sections of pipe, for which a post installation test is impractical, a preinstallation strength test must be conducted by maintaining the pressure at or above the test pressure for at least 4 hours.
http
RE: Pneumatic test o hydrostatic one for a Tie-In??
In my opinion, pneumatic testing is a "last resort alternative" to hydrotesting not an either/or, flip a coin choice.
Talk to your jurisdiction authority.
Frank "Grimey" Grimes
Rule 25. of Swanson's "Unwritten Rules of Management"
Have fun at what you do. It will reflect in your work. No one likes a grump except another grump.
RE: Pneumatic test o hydrostatic one for a Tie-In??
" Would be possible just to do the hydrotest over the Tie-In (only including the blind, spectacle, gate vale and split tee) without doing the hole (without extraction the coupon) and then consider the complete line downstream chequed?"
Make sure you also follow "zdas04's" cmments about welds and welder qualifications.
And then, I say yes you can do this.
RE: Pneumatic test o hydrostatic one for a Tie-In??
For pipeline work under B31.4 or B31.8 and/or CFR 49, parts 192 (Gas) or 195 (liquids), Hydrotest any fabricated assembly before tying-in. Lower and tie in the fabricated assembly, then X-Ray the tie-in welds.
Pneumatic testing cannot be done to as high a pressure as would be permitted when using water, thus the resulting allowed maximum operating pressure of the completed and tied-in assembly might be very much under the maximum allowed operating pressure of the whole pipeline. Not a good situation.
The alternative is to lower in, tie in then plug the upstream and downstream pipeline segments (with a hot tap plug or a freeze plug or similar device), then test the fabricated asssembly including the parts of the pipeline between the plugs. Way too much trouble, unless there is absolutely no other alternative.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Pneumatic test o hydrostatic one for a Tie-In??