RE: Dissimilar Piping Materials

From: <Christopher>
Date: Wed Jun 13 2001 - 10:51:00 EDT

>My interest is not really on the qualified weld procedure but more on the
>stresses created as a result of joining two dissimilar pipe metals say for a
>process with a normal operating temp of say 740degF.
I gather you mean weld residual stress. This is a pretty tough problem--the only way I've ever seen it approached is with FEA, and even then it's not all that great. I seem to recollect reading somewhere that residul stresses are locally 1/2 to 3/4 of the yield strength, but I'd only take that as a guess. Even metals with the same P-number have residual stresses of this magnitude because of shrinkage during cooling, so it may be a little tough to sort out how much of that is due to cooling and much is due to metallurgical differences. The best place to find out actual numbers is references on the AWS web site.

Christopher Wright P.E. |"They couldn't hit an elephant from <a href="/group/PipingDesign/post?postID=l-iMsH17--KDGXkZy9uTbCfqsEXoVmX9_sa39LUkQnflAQare1D4kzsdCzGub37tjp4PC660UtWa">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 Wed Jun 13 10:51:00 2001