This specification establishes requirements for dimensions and gaging of taper pipe threads used on threaded plastic pipe and fittings. The type of pipe threads are designated by specifying in sequence the nominal pipe size, number of threads per inch, and the thread series symbols as follows. For left-hand threads add LH to the designation, otherwise right-hand threads will be understood. Different physical properties of pipe threads such as form, dimensions, angle, truncation, height, sealing capacity, and tightness shall be in accordance with the requirements specified. The gages have two types which may be used to completely cover gage requirements: (1) master gages used to check working gages; and (2) working gages used to check threads during manufacture and for conformance inspection. Both external and internal taper threads shall be gaged.

1.1 This specification establishes requirements for dimensions and gaging of taper pipe threads used on threaded plastic pipe and fittings.

1.2 Threads meeting this specification shall only be used on those plastic materials deemed suitable by the manufacturer.

1.3 Specialty threads or threads not requiring a leak-tight joint are not covered in this specification.

Note 1: The terms “wrench makeup” and “wrench tight” are standard terminology for tightness and do not imply using a pipe wrench or other tools which would damage plastic pipe and fittings. The terms “hand-tight” and “hand-tight engagement” refer only to thread gaging (not pipe and fitting connections) and is the definition of the L₁ gage length.

1.4 Thread Designations—The type of pipe threads included in this specification are designated by specifying in sequence the nominal pipe size, number of threads per inch, and the thread series symbols as follows in accordance with ANSI/ASME B 1.20.1: ³/₈-18 NPT. For left-hand threads add LH to the end of the designation, otherwise right-hand threads will be understood. For example: ³/₈-18 NPT-LH.

1.4.1 Each of these letters in the symbol has a definite significance as follows:

N

=

National (American Standard)

P

=

Pipe

T

=

Taper

1.5 The values stated in inch-pound units are to be regarded as the standard. No other units of measurement are included in this standard.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see 7.2.1 and 8.3.

1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.