In article , Gary Coffman says...

(NPT threads)

They're *tapered*. That means you don't have full depth threads
engaging full depth threads at any point in the joint.

I certainly agree with your conclusion, but NPT threads
are designed to have full thread engagement. The
taper angles match. Imagine a morse taper with the
ID and OD threaded.

Machinery's
Handbook says that only NPS threads should be used for axial
loading.

Strong agree on that.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================