Re: pressure test thoughts

On Sep 7, 2005, at 9:18 PM, jcluf wrote:

> I assure that I have been involved with and charged many profitable
> hours in re-rating piping systems.

I'll defer to your experience. In fact I've been asked to 're-rate' vessels on occasion. I wouldn't touch it because I have absolutely no idea of the vessel's actual service, and because it violates the National Board rules, as I've mentioned. I think it violates most state pressure vessel laws, too, although Minnesota makes allowances for the use of non-Code vessels, so presumably other states do too. Your point about spotty regulation is well taken, but it seems like you're talking about loopholes in laws, not engineering practice.

I'm probably giving some offense here, but I've seen a few cases of something very much like 're-rating,' one in particular where a second-hand tank was put into service with the original code plate chipped off and a scrapped code plate slipped into the little frame where the flammability tag is placed. The vessel later blew up when the botched welds over a patched inspection opening let go. Probably not what you have in mind when you talk about re-rating, but this vessel had supposedly been 'checked out,' too, and probably the guy who did it charged some profitable hours, too. But the plant burned down, anyway.

That said, I suspect it's theoretically possible to re-rate a vessel, provided you know enough. I've just never seen a vessel where anyone actually knows enough. But I'll check out the piping Code appendix anyway.

Christopher Wright P.E. |"They couldn't hit an elephant at chrisw@skypoint.com | this distance" (last words of Gen.

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