National Pipe Thread
National Pipe Thread
(OP)
I am not completely familiar with NPT. How do you read an NPT callout. I know we don't need to call out depth, as that is per machining spec.
The callout is a 1/8-27 NPT. Is the 27 just referring to threads per inch? And since an NPT hole is tapered, is 1/8 the diameter of the inside part of the hole or the outside?
I just want to make sure of what I am getting made so I can purchase the proper fittings.
The callout is a 1/8-27 NPT. Is the 27 just referring to threads per inch? And since an NPT hole is tapered, is 1/8 the diameter of the inside part of the hole or the outside?
I just want to make sure of what I am getting made so I can purchase the proper fittings.





RE: National Pipe Thread
Jeff Mirisola, CSWP
Design Manager/Senior Designer
M9 Defense
My Blog
RE: National Pipe Thread
RE: National Pipe Thread
Engineering is not the science behind building. It is the science behind not building.
RE: National Pipe Thread
RE: National Pipe Thread
1) You just call out 1/8 NPT. I like to put on 1/8 MNPT, "M" for male or Pin, 1/8 FNPT, "F" for female or Box, but I find the machine shops prefer not to use such identification on the prints.
2)the "1/8" is a nominal size reference and has no physical meaning. The OD for this NPT geometry for example is 0.405 inches on the male.
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada
RE: National Pipe Thread
RE: National Pipe Thread
Regards,
Mike
RE: National Pipe Thread
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada
RE: National Pipe Thread