Hydrotest Pressure 1

Not explicitly. Many people take the test pressure as a minimum (i.e., they fill the pipe to some specified number greater than the test pressure and set their success critera as a final pressure no less than the test pressure. That kind of latitude is really important if the pipe has a cold section (e.g., the pipe goes under a river) and the test-water will be cooling for the entire test.

David

QCMike

I've often seen it 90% of SMYS as a minimum & 110% as a maximum.

Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website:

There is no need for a tolerance. You must test to at least the test pressure; the maximum would normally be to less than yield, however I have tested to 110% SMYS.

Where a wider ranging test comes in handy is when you must test a pipe segment that has a large elevation change. If temperatures are expected to change such that you would go outside your elevation range too much, it would be better to test on another day if it was possible to do so, since it might be very difficult to reach a stabilization point beforehand.

HDPE piping does not behave like steel pipe during a hydrotest. It stretches as pressure is applied and you think you have a leak. See the PE (Polyethylene) Handbook from the Plastic Pipe Institute (PPI) for methods - Chapter 2 for testing recommendations.


Also if black HDPE pipe is in an open ditch, the sun can really warm it up, easily over 100F. The temperature causes a "de-rating" of the piping & it will fail under much less pressure than expected.

Good luck - MJH

Cl302.3.6b) applies and states that stresses due to hydrotest are not subject to the limitations of clause 302.3.

Cl302.2.4 e)& f) apply in that if you rely upon occassional loads derived from pressure then the hydrostatic test pressure should be at least that high.

Geoffrey D Stone FIMechE C.Eng;FIEAust CP Eng