B31.8 Hydrotesting, Compressor Station 1

[pmover]

All,

Is there a code interpretation that defines the limits on non-hydro-tested piping modifications in a natural gas compressor station? I understand there must be tie-in welds which are not hydro-tested, but how far can you take this? I'm being told that hydro-testing pipe prior to welding is sufficient.

thanks!
-pmover

 

[DLite30]

See CFR pt 192.505.e

I can tell you how we interpret this...it makes reference to limiting non-tested (pressure tested) projects to single items, such as one single fitting, or one pup. Any more than one fitting weleded together constitues a "fabrication" which much be hydrotested prior to or after installation.

For example if you have tested pipe on-hand (which we sometimes keep on hand for repairs) that you want to use to weld some pups onto a tee allow for field trimming, then that constitutes a fabrication which much be hydrotested prior to or after installation.

We only allow single fittings to be welded without pressure testing. An example would be weling on a threadolet, dye-pen testing and plugging it. Or cutting off a weld cap at the end of a header, then welding on a flange, and blinding it off.

Generally we try to hydrotest everything after it's in place, and make allowance for flanged spool pieces to rotate and blind off...and really try to eliminate any cutting after testing.

"Short section of pipe" is open to interpretation...

Each company is going to interpret this a little different.