Interchangeability of Threads
Interchangeability of Threads
(OP)
Are Line Pipe Threads and NPT Threads interchangeable? If not, please explain what are the differences between these threads. If NPT threads would suffice the need, why Line Pipe Threads are required ? What are the torque requirements for Line Pipe Threads and NPT Threads ? How to calculate the torque values ?





RE: Interchangeability of Threads
The torque values would be difficult to calculate. The tapered thread complicates the approach. An estimate of the pressures between thread faces can be made as a function of torque but I believe that most specifications of torque are based on acceptable past performance. I have found torque specifications published by manufacturers for internal company use. MIL standards also contain torque requirements as part of the qualification testing process. Qualified fittings must be sampled. A performance test (static hydroproof) is performed on fittings that have been assembled to proper torques. This is a good reference for operational data.
RE: Interchangeability of Threads
RE: Interchangeability of Threads
http://home.earthlink.net/~delaero/
- Hope this helps...
RE: Interchangeability of Threads
but NPTF threads are just variants of NPT threads i.e with fine pitches & some other dimensional differences. But LP threads are different. Thanks for the web page address. But it has only torque values of conical seal fittings and not for taper threads.
Thanks a lot any way.
RE: Interchangeability of Threads
RE: Interchangeability of Threads
Why not junk NPT in favour of HP UNF coned fittings? Up to 150,000 psi and with no dubiety over the torques or performance of the thread. Just a thought.