"Couple of things. Don't assume that allowable deflection is the same as allowable stress or allowable load. Deflection will govern how seals perform, but allowable loading will affect fatigue behavior in the undercut pipe. People tend to assume that fatigue isn't a problem because most piping codes and Section VIII-1 don't require fatigue analysis. That doesn't mean that fatigue failures can't happen."
The problem was found to be in the seals. The lines were not subject to vibrations and since the temperatures were low thermal cycling was also insignificant. For vibrating lines of course the fatigue is checked . The worst affected are the fillets at the small bore branches. We had repaired numerous of them in our plant. Received on Wed Oct 16 08:22:00 2002
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