Re: Vessels not failing in hydro test

From: <Christopher>
Date: Mon Aug 29 2005 - 13:02:00 EDT

On Aug 29, 2005, at 10:27 AM, Tony Paulin wrote:

> You would roughly have to double the hydrotest pressure to produce a
> boundary failure (longitudinal fishmouth opening) in the cylinder,
> although
> actual values are a bit higher.

I think this is the result of strain hardening. The PVRC has some really good papers on the topic.

In theory you'd approach the yield point in a hydrotest if you had an infinite cylinder made from annealed 304 stainless, but 304 strain hardens hugely, so there's no chance of burst, and the presence of heads tends to suppress objectionable plastic deformation. You don't want to go much over the Code-specified proof factors for stainless, though, because you stand to get enough plastic deformation so things don't fit together like they should.
Christopher Wright P.E. |"They couldn't hit an elephant at <a href="/group/PipingDesign/post?postID=0gptwxyZ7ATgOYsI8UiOapSuZMe_DWXXGhb5KK5qCi-5BhgHeP3XHaGxiJfiVE4iKaiJw2E1ucT_uobxLaE">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 Aug 29 13:02:00 2005