Re: flange stud bolt replacement criteria.

From: <Christopher>
Date: Thu May 05 2005 - 09:47:00 EDT

On May 5, 2005, at 5:50 AM, Steve McKenzie wrote:

> To those who think this is madness, check your wrench calibrations over
> say 10 tests in different positions, and also compare the extension of
> a
> good smooth threaded stud with a bad one. You may get a surprise.
Torquing involves so much friction that the preload accuracy is only about 25% anyway. If the fitters are very good about chasing threads and lubricating joints, you can do a reasonable job calibrating a torque wrench against a bolt pretensioner. The biggest problem with flanges is soft gaskets which bugger the joint stiffness. Your method is probably as good as any. If you have a fairly stiff connection the turn-of-the-nut works pretty well, but may require re-tightening under pressure to avoid leaks.

Christopher Wright P.E. |"They couldn't hit an elephant at <a href="/group/PipingDesign/post?postID=Bdl-R2Kxcy2Q3eXbu1gUo5osDjQnw41bx2R7J4cli19vSwKlDnGVrk9YhK8Po9Kat9IB6WZu1snhmk4">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 Thu May 05 09:47:00 2005