In article LIzib.6306$Eh3.2408645
@news4.srv.hcvlny.cv.net, says...
"Ned Simmons" wrote in message
...

The argument that tapered pipe threads are not intended to
carry a tension or compression load is nonsense. (I don't
mean to imply you said this, Jim.) If there is pressure in
the pipe, then there is an axial force on the joint equal
to the pressure x area of the pipe ID.

Ned Simmons

And that may run a couple of hundred psi.

Which gives us the lower bound on the axial strength of the
threads, but says nothing about the upper bound. Much
higher pressures are acceptable with forged fittings and
heavy wall pipe. 3000 psi fittings are readily available up
to 4" NPT(F), 6000 psi up to at least 2".

Those loads on plumbing pipe from
internal pressure are nowhere near the strength expected of mechanical
tubing in tension or compression, Ned.

I don't see how that's relevant. The question is not what
the optimum solution is, but rather, can pipe threads carry
significant axial loads. Clearly they can.

Ned Simmons