Limits of Reinforcement 2

[ME231]

Is it permissible under code (VIII-1) to consider material (over and above the thickness required to resist pressure) in threaded (NPT) fittings as having reinforcing value? I could not conclusively decide one way or the other after reading UG-43.
Thanks in advance to the forum for your feedback!

 

[SnTMan]

ME231 Your proposed construction is not clear, are you attempting to use a pipe threaded into an opening to reinforce the opening? I don't see how this could be justified.

If you are attaching a threaded connection to a vessel wall such as by welding, then any thickness above that required for pressure and with allowances for corrosion and threading may be counted as reinforcement.

Regards,

Mike

 

[ME231]

SnTMan,
The nozzle that goes on the opening has a NPT (tapered) thread. so no welding is necessary - the pipe threads would be installed with PTFE tape.
My question is, for such an unwelded construction, would extra material in the nozzle count as having reinforcing value?
Thanks!

 

[gr2vessels]

ME231,
The threaded attachment you call nozzle is not part of the vessel, hence the thickness of the fitting is irrelevant to the vessel reinforcement (ie the extra material in the nozzle counts only for the fitting minimum thickness and has nothing to do with the vessel reinforcement). The properly attached fitting refers to a welded attachment on the shell to accommodate the required length of thread.
Cheers,
gr2vessels

 

[TomBarsh]

gr2vessels is absolutely correct. Consider it as this: to be able to reinforce the shell with the strength of the "nozzle" (the pipe threaded into the shell), the forces must be transferred from the shell into the "nozzle" through the PTFE tape. The mechanical strength of the PTFE tape is likely quite small compared to the metal of the shell and pipe, and cannot transfer any large forces. And for that matter, the forces to be transferred will be a tensile force through the thickness of the tape, how will this force be transferred from the shell to the surface of the tape? It won't be unless there is some form of adhesive. No, this is not a realistic load path at all.

 

[ME231]

Thank you both for your responses. I had a hunch but didn't quite have a good reason to disregard the excess material in the "nozzle". Now I do - Thanks again.