Re: pressure test thoughts

From: <Christopher>
Date: Sat Sep 10 2005 - 11:39:00 EDT

On Sep 10, 2005, at 5:06 AM, Venkat hariharan wrote:

> Rerating of existing piping systems to a higher value is allowed as
> per API 570 - Inspection, Repair, Alteration and Rerating of in
> service Piping Systems

The API Codes don't have legal standing like the ASME Codes, in the US. I don't want to beat this to death, but just because a Code says something doesn't make it prudent or legal. I think when I started all this about what the Codes do and do not approve, I wasn't very clear. The ASME Code doesn't prohibit re-rating, it simply doesn't cover it. You can cherry pick through Codes and books and come up with a rationale for saying that the stamped MAWP is too low, and the only thing standing in your way would be jurisdictional requirements, including OSHA or your insuror's requirements.

Over the years I've run into situations where the Code plate is a legal requirement for a vessel to be placed in service--no plate, no service. The vessel could have been made in a Code shop and all the equations copied carefully out and the rest of it, but if there wasn't a Code plate, the vessel couldn't be used. This was in California, I think. Same for Coast Guard approval for shipboard use. I'm sure in Louisiana or Texas, where the oil business runs the legislature, refineries are exempt from the pressure vessel laws that apply to everyone else. And I've already beaten Minnesota's exemptions to death--everyone knows them by now. So yes, it is physically possible to do whatever you want, but when you start taking exception to what's stamped on the Code plate, you're sticking your neck out, both technically and legally. Christopher Wright P.E. |"They couldn't hit an elephant at <a href="/group/PipingDesign/post?postID=0mhVrbmekCP63bRdWjT0nhYQSG9NrLvi9BmZ5IThCwajL_O8NhfOwWAby9DPz3KBNyuHpRIawHtShw">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 Sat Sep 10 11:39:00 2005