Mechanical

[dqshen]

I will appreciate if someone can help me to find the calculation formular for pipe thread tensile stress and the relation between applied torque and force for pipe thread as well. Thanks in advance.

 

[diamondjim]

Can you be more specific? Are you talking about
BSPP threads which are parallel threads or are you
speaking of a tapered pipe thread. How large of
threads are you speaking? Is you question only
in general?

 

[dqshen]

Diamondjim,
Thank you for your reply. The size of pipe threads are 1/4-18 NPT and 1/8-27 NPT. Thanks again.

 

[diamondjim]

dqshen,
Looking at machineries handbook and other
sources, I found nothing about torque, except
something in effect not to overtighten as it
may damage the threads. The guys in the shop
say to tighten them snug plus a 1/6 turn.
It may be of interest that some of these are
90 degree fittings which mean that they should
be oriented toward the bearing center or the
bearing o.d. which implies that 1/2 turn may be
alright in the worst case. I assume you are
using these for grease applications.

 

[evelrod]

Just a bit of humor her---

"Tighten until stripped, then back off 1/2 turn!"


Rod