Re: RE: [Piping Design] Hydrotest pressure

From: <Christopher>
Date: Tue Nov 01 2005 - 11:32:00 EST

On Nov 1, 2005, at 12:03 AM, RICK wrote:

> Is it necessary to calculate for other stresses other than calculating
> the required thickness as required by ASME B31.3 304.1.2(3a)?

The short answer is yes. You need to do that for any installation of the sort.

If you were working for me, I'd want to know if the upgraded installation complied with code rules just as if it were new. In fact, you're going to test it as if it were new. You owe it to your client (and yourself) to make a reasonable assessment of the suitability of the upgrade for the new service conditions. That should include determining that all Code stress levels are met in the corroded condition.

If you're asking for chapter and verse in the Code, I can't recite it, if only because the PV and piping codes cover only new construction. Strictly speaking an increase in the working pressure of a system is not permitted by any Code, so my reasoning is simply what I consider to be good judgment. I don't know enough about what you're doing to say exactly what you should look at. In general you should treat it as if it were new construction; good judgment also says you should consider what might have happened since it actually was new. If it were me, I wouldn't go ahead with the work without inspecting the old pipe carefully for damage and corrosion.
Christopher Wright P.E. |"They couldn't hit an elephant at <a href="/group/PipingDesign/post?postID=Dhu-iW-cws0XtTLiZLUm18ZH9CtjmlWO0g2dykzHqE_Q4crsDPFSV8gnxNjntUtqlb0l-aVacVssNQ">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 Tue Nov 01 11:32:00 2005