From: <Christopher>
Date: Fri Aug 10 2007 - 13:27:00 EDT

For anyone who's interested--

> My 2001 version of ASME VIII - Div 1 states in UG-99, that vessel
> hydrotest pressure is to be "at least equal to 1.3 times the
> maximum allowable working pressure".

This is correct according to the 2005 addenda. The 1.5 proof factor in _…Simplified_ probably slipped through the review.

> Has the ASME Code been updated since 2001, to raise the hydrotest
> pressure, or is this a mistake in the "Pressure Vessel : ASME Code
> Simplified"? The difference is obviously significant, with
> potentially major cost impacts if previously "in-spec" vessels are
> now out of spec!

The Code inherently cannot render vessels non-compliant, which were constructed under previous versions. First, the Code only applies to new construction. The Code jurisdiction ends once the vessel is stamped. Second, changes in the Code are always less restrictive than previous provisions covering the same subject matter. It may be that new provisions are added which weren't present in previous editions, like the section on determining the MDMT, but they aren't considered retroactive, since they apply to new, not existing, construction.

   The hooker is that a local jurisdiction could conceivably rule that particular provisions of one edition of the Code be made retroactive, despite how the Code itself is intended to work. I don't know of any such instances, but there'd be nothing besides political pressure preventing such a thing. The Code itself has no legal standing until a local jurisdiction makes it part of a law, and such jurisdiction has the final say on how it's adopted. For example, a state or Province might decide in its wisdom that any vessel not incorporating impact tested material is simply too dangerous to use, and such vessels are to be replaced. (Actually, I think something of the sort is worth considering). There's nothing beyond political pressure following great outrage in the business community to prevent such a thing, so it's not likely to happen.

[BTW, John Luf--I believe this is the way the piping Codes work, too. Am I right?]

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

.......................................| John Sedgwick, Spotsylvania
http://www.skypoint.com/~chrisw/ Received on Fri Aug 10 13:27:00 2007

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