Threaded Drain Plugs on Hydrotested Equipment

[Mechomatic]

Couldn't quickly find a thread on this, but I wanted to confirm:

ASME hydrotest for Section VIII, Div. 1 vessels: No welding or grinding permitted after the hydrotest is complete (or the vessel must be hydrotested again). If I need to ensure that ALL the hydrotest fluid is drained from a series of tubes/returns, is it acceptable (in the eyes of UG-99) to use threaded plugs in thread-o-lets in the pipe returns so the plugs can be pulled post-hydrotest to drain the system, then re-inserted "permanently"? Is that an acceptable practice (beyond the letter of the code)?

Thanks!

 

[SnTMan]

WPratesi, threaded plugs are used all the time. I would be careful about having a number of internal, threaded plugs where future leakage could be troublesome.

Under some circumstances they may be seal welded after the hydro, and you might look at alternate ways to drain to minimize the plugs needed, such as blowing down, rolling the unit, etc.

Regards,

Mike

 

[moltenmetal]

Strike an arc to the device after hydrotesting and I'm likely to be upset with you if I'm the customer.

That includes seal welding in a plug, attaching insulation support clips etc.

Better check with the customer before assuming they're going to be OK with seal welds post hydrotest.

You have to balance the potential future leakage at drains installed ONLY for the hydrotest against the risk of not draining completely post test. If you can move the vessel post test, you have more options for draining from existing flanged nozzles.

 

[SnTMan]

Yes, one of the circumstances being by agreement of all parties