Minimum number of threads required
Minimum number of threads required
(OP)
Hi,
I need to calculate Minimum number of threads required for two pipes to engage, The Pipes are having NPSM (American Standard Straight Mechanical Pipe Thread)
Pipe size = 4"-8TPI (NPSM Thread)
The pressure in the pipe is around 75 PSI.
I have considered two threads for engagement, Is this sufficient to withstand 75 psi pressure ?
Thanks in advance
I need to calculate Minimum number of threads required for two pipes to engage, The Pipes are having NPSM (American Standard Straight Mechanical Pipe Thread)
Pipe size = 4"-8TPI (NPSM Thread)
The pressure in the pipe is around 75 PSI.
I have considered two threads for engagement, Is this sufficient to withstand 75 psi pressure ?
Thanks in advance





RE: Minimum number of threads required
At 8TPI, 2 threads would give 1/4" engagement, on 4" tube and at 75 PSI, that is hardly likely to stay intact.
RE: Minimum number of threads required
Please read the forum policies (there is a link below my signature), and pay particular attention to policy number 4, which does not permit posting the same question in different forums.
I recognize that this is your first day of membership, but you have already made cross-posts with two different topics. Putting the same post in multiple forums creates confusion and costs experienced members valuable time.
Please red-flag one of your two identical posts in each case (I suggest this one for the pipe thread engagement issue).
Good on ya,
Goober Dave
Haven't see the forum policies? Do so now: Forum Policies
RE: Minimum number of threads required
Good on ya,
Goober Dave
Haven't see the forum policies? Do so now: Forum Policies
RE: Minimum number of threads required
htt
But, 2 turns doesn't seems reasonable to me, consider first turn of any thread can not not be full engaged.
RE: Minimum number of threads required
...around 75 PSI
... two threads ...
This just sounds like a bad idea for several reasons
RE: Minimum number of threads required
Regards
rhg
RE: Minimum number of threads required
I'm not sure what code you are designing to but for reference you can check out table PG-39 in Section I for guidelines on minimum thread engagement. For 4" NPT the minimum allowable by this code is 7 threads into a plate of 7/8" thick. Also, as Spoonful stated - don't count the 1st thread because it is usually not properly formed.
-Steris
RE: Minimum number of threads required
Most pipe threaded joints in the USA follow the ASME B31.1/B31.3 piping codes......which call for NPT threaded joints.
With NPT joints, seven threads (as stated above) makes a proper joint.
My opinion only..
RE: Minimum number of threads required