Re: Flange Failure Images

From: <Christopher>
Date: Thu Jan 29 2004 - 16:09:00 EST

>except I dont see any
>welding on the failed flange and i dont see where the welding relates.
You may be right. I thought I was seeing the remains of a fillet towards the bottom of the pipe in slide 2. There's nothing on the ring itself that I can see. Wonder if this is a lap joint ring mated to an ordinary slip-on or weld neck.

> (i cant see the flange ring welded to the pipe being the case because the
>flange ods line up and the bolt position has not changed radially (no
>stretch) and the pipe hasnt "shrunk").

If it were a lap ring , overtightening would produce the radial cracks at the bolt holes. There would be a gap between the ring ID and the pipe wall which would open up under tightening as the the ring ID rotates out and away from the pipe OD.

>It strongly appears to be an illegitmate slip on ring flange. if made out of
>improper material the failure would occur as seen at the stress raisers of
>the holes.

Bang on. Looks like cast iron maybe with a coat of primer. I wonder if that light-colored stuff at the OD is caulk, laid in as a desperation measure.

Christopher Wright P.E. |"They couldn't hit an elephant at <a href="/group/PipingDesign/post?postID=jG5eqA4-55ofGvMFneIbZUB5zc1TrS77_0B5YhUtWmvAM6oo2_hh-mAs_M_ySDEXn69wBCnlsKIQ9A">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 Jan 29 16:09:00 2004