NPT confusion
NPT confusion
(OP)
I just came up against this spec that gives different nominal OD of NPT threads than all other sources I've checked. For example, it says for 1/8 thread nominal OD is 0.391 while all others including Machinery Handbook says it is 0.405; for 3/4, it says OD is 1.022 but all others say it should be 1.05 & so on. Pitch is same for both in all cases.
Can anyone please tell me what am I missing?
Thanks.
Can anyone please tell me what am I missing?
Thanks.





RE: NPT confusion
More info here,
http:/
"I think it would be a good idea."
- Mahatma Gandhi (1869-1948),
when asked about Western civilization
RE: NPT confusion
RE: NPT confusion
I don't have the B1.20.1 spec, but my Piping Handbook shows 0.405 & 1.05 too.
"I think it would be a good idea."
- Mahatma Gandhi (1869-1948),
when asked about Western civilization
RE: NPT confusion
I see nothing with a diameter listed as 0.391-inch. Table 2 shows the O.D. of the pipe as 0.405. The pitch diamter at beginning of external thread E0 is 0.36351 and E1 diameter (pitch diameter at gauging notch) is 0.37360. The diameter E3 wrench makeup length for internal trhreads is 0.35656 E5 nominal completer external threads diameter is 0.37537.
RE: NPT confusion
What is the media to be contained?
RE: NPT confusion
RE: NPT confusion
2.5.4.3 Pressure Tap Diameter
The diameter of the pressure tap holes at the inner surface of the meter tube and along the drilled length of the holes shall be 3⁄8 (0.375) inch ± 1⁄64 (0.016) inch, providing for a maximum diameter of 0.391 inch and a minimum of 0.359 inch for pipe with a nominal diameter of 2 or 3 inches; and shall be 1⁄2 (0.5) inch ± 1⁄64 (0.016) inch, providing for a maximum diameter of 0.516 inch and a minimum of 0.484 inch for pipe with a nominal diameter of 4 inches or more.
RE: NPT confusion
In any case I think as others have said it is best practice to precisely identify what one is talking about with a standard specification and or drawing reference!