Re: RE: [Piping Design] Hydrotest pressure

From: <Christopher>
Date: Mon Oct 31 2005 - 23:11:00 EST

On Oct 31, 2005, at 12:30 PM, RICK wrote:

> Based on my calculations the old pipe will experience near SMYS
> stresses during hydrotest which our QA/QC guy wants to hold test
> pressure for 4 hours. Would the pipe be usable after the hydrotest
> considering the stress it encountered?
The yield stress of SA-53 gr A is 30 ksi and the stress at test pressure will be no larger than 885(20)/(2)(.375) = 23.6 ksi. If you're using SA-53 gr B the yield stress is 35 ksi. I'd say you're fine.

I notice you didn't mention any of the usual possibilities: corrosion reducing the wall thickness below 0.375 in, possible weld defects in the process of turning into fatigue cracks, extraordinary loads that might be applied during the hydrotest. You should verify that your stress calculations based on internal pressure alone are accurate for the conditions of the test.

Christopher Wright P.E. |"They couldn't hit an elephant at <a href="/group/PipingDesign/post?postID=SoWQtWOSUJ9iOHTGB0T4UUBq3c7i6DKVcg0n5z0VJyOMkKikatkT7DQyBvl4FGaZPMLhwSkRBkj_ikxV">chrisw@skypoint.com</a> | this distance" (last words of Gen.

.......................................| John Sedgwick, Spotsylvania

1864)
<a href="http://www.skypoint.com/~chrisw/">http://www.skypoint.com/~chrisw/</a> Received on Mon Oct 31 23:11:00 2005