Can anyone shed some light on ANSI B1.20.3? I am in the Pressure vessel business and have a customer requesting Torque Specs on NPTF fittings. I am aware of and use rules of thumb for NPT's. I also need defomation and reusability characteristics of these fine pipe threads.
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Torque Values for NPTF Threads 1
- Thread starter Jethro31
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NPTF threads are derived from the NPT thread form adjusted to achieve metal to metal contact at the root and crest of the threads when they are assembled. The are not any finer than NPT threads. Check Machinery's Handbook for a good writeup on these threads. I doubt you will find any torque specs, because with metal to metal contact and the vagaries of thread creation, torque values would be all over the place. It would be much better for you to recommend to your customer to specify makeup of the joint by number of exposed threads after the join has been made wrench tight.
They have it,check links and files.
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