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nozzle repad

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mdischarge

Mechanical
Joined
Feb 21, 2006
Messages
9
Location
CA
for shell or head thickness over 40 mm , the repad should be integrally attached to the nozzle. any reason?
thanks
 
Well on a practical sense, the amount of heat from the weld you need to attach the re-pad can cause some distortion or the base metal to sink.
 
First off, is this a Code requirement? For some reason I don't recall this as a requirement.

Second - if this is not a code requirement it is a good practice to do because it provides additional load carrying capacity, and in my opinion increases resistance to failure from fatigue crack propagation in service.

The code only requires a fillet weld for the joint between the repad OD surface and the nozzle. However, I have seen fatigue crack propagation off the toe of this fillet weld into a nozzle, and have seen cracking that started from the nozzle/shell weld underneath the repad. This resulted in a leak thru the tell tale hole. I always require full penetration tie in between the repad and nozzle, with an external fillet weld, in lieu of only a fillet weld.
 
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