ASME B1.20.1 (2013)

Pipe Threads, General Purpose, Inch

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Annotation and contents

ASME’s widely-referenced B1.20.1 Standard on Pipe Threads, General Purpose, Inch covers dimensions and gaging of the world’s most common pipe threads:  NPT, NPSC, NPTR, NPSM, and NPSL.

From critical applications demanding robustness and precision to common plumbing and hardware, these threads are used everywhere in the United States and abroad. 

This long awaited revision incorporates both subtle and substantive changes, including:

  • Moving of the gaging point of reference of external threads in certain circumstances;
  • A new acceptability section for instances of gaging disputes;
  • A change to parameters, facilitating the calibration of working gages;
  • Guidance for plated or coated pipe threads;
  • Better explanatory language for the lay-user.

This is the foundational Standard for NPT, NPSC, NPSM, and NPSL pipe threads.  All companies that manufacture, sell, or use these threads should have this revision in their technical library.

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