This standard specifies parallel pipe threads and is applicable to the threads used mainly for mechanical connection to joint the pipes, pipe fittings, fluid machinery, etc. The parallel internal pipe thread of Class B of PF 1/8 to PF 6 in thread designation and the parallel pipe thread of PF 7 to PF 12 in thread designation shall be as specified in Appendix (normative).

ISO 228-1:2000 - Equivalent