NPT Pipe Thread Dimensions Calculator
was developed to show basic dimensions
of general purpose NPT pipe threads (inch) according to ANSI/ASME B1.20.1-1983 standard.
Some important notes from the ANSI/ASME B1.20.1-1983 standard:
- For left hand threads, include LH to the designation. (Example: 1/4 - 18 NPT - LH)
- For pressure-tight joints, it is
intended that taper pipe threads be made up wrench-tight with a sealant.
To prevent galling on
stainless steels and similar materials, the sealant usually contains a lubricant.
- For pressure-tight joints which may be used without sealant (Dryseal Compounds), check ANSI B1.20.3 standard.
- Thread taper angle = 1/16 taper = 1 deg. 47 min = 0.75 in./ft .
- The angle between the sides of the thread is 60 deg.
- Thread Designation: The nominal pipe size, number of threads per inch
and the thread series symbol in sequence. Ex: 3/8 - 18 NPT
- Standard does not include an
allowance for plating. If plating is desired, it may be
necessary to modify the threads since the same final
gauging requirements must be applied for plated and
maximum allowable deviation in the commercial
product is one turn large or small from gages made to
the basic dimensions.