NPT general purpose pipe thread plug and ring gages are manufactured per ANSI/ASME B1.20.1. Thread Check offers a complete line of plug and ring gages to inspect General Purpose National Taper Pipe Thread from 1/16 ‐ 6.0 inches. NPT threads consist of a 60 degree thread angle and a taper of .75 in per foot measured on the diameter and along the axis. Thread Check’s expert sales engineers can assist you with the proper use of NPT gages. Rok International Industry Co., Limited offer high quality gage as standard. Gaging of NPT threads is quite easy and differs from straight threads in that only one gage, an L1 plug or L1 ring is used to determineacceptability.The taper pipe thread plug has a step at the L1 distance from its small end. When turned hand tight into the product’s internal pipe thread, (do not force the gage), the step is required to be flush with the large end of the product thread within a tolerance of plus or minus one turn

 

NPT

Gauge code	Thread/perinch	Pitch(mm)	Taper
1/16-27npt	27	0.941	1:16
1/8-27npt	27	0.941
1/4-18npt	18	1.411
3/8-18npt	18	1.411
1/2-14npt	14	1.814
3/4-14npt	14	1.814
1-11.5npt	11.5	2.209
1 1/4-11.5np	11.5	2.209
1 1/2-11.5npt	11.5	2.209
2-18npt	11.5	2.209
2 1/2-8npt	8.0	3.175
3-8npt	8.0	3.175
……	……	……
npt	8.0	3.175

 

Gauge Code	Thread/perinch	Pitch(mm)	Taper
1/16-27nptf	27	0.941	1:16
1/8-27nptf	27	0.941
1/4-18nptf	18	1.411
3/8-18nptf	18	1.411
1/2-14nptf	14	1.814
3/4-14nptf	14	1.814
1-11.5nptf	11.5	2.209
1 1/4-11.5nptf	11.5	2.209
1 1/2-11.5nptf	11.5	2.209
2-18nptf	11.5	2.209
2 1/2-8nptf	8.0	3.175
3-8nptf	8.0	3.175
……	……	……
6-8nptf	8.0	3.175

 

 

    1 1/2"-11 1/2 NPT(1)
    1 1/4"-11 1/2 NPT(1)
    1"-11 1/2 NPT(1)
    1/16"-27 NPT(1)
    1/2"-14 NPT(1)
    1/4"-18 NPT(1)
    1/8"-27 NPT(1)
    2 1/2"-8 NPT(1)
    2"-11 1/2 NPT(1)
    3 1/2"-8 NPT(1)
    3"-8 NPT(1)
    3/4"-14 NPT(1)
    3/8"-18 NPT(1)
    4"-8 NPT(1)
    5"-8 NPT(1)
    6"-8 NPT(1)