NPT Thread Gauges

NPT Thread Gauges

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NPT THREADS are used in general purpose application of pipe assembly, where a pressure tight joint of pipes is made, by making the pipes wrench tight using a sealing compound.


ANSI/ ASME B1.20.1 : 1983 for Basic Type Gauges & American Handbook H-28 Part II : 1957 for Step Limit type.

Manufacturing Range :

Thread Plugs, Thread Rings, Check Plugs & Wear Check Plugs of Diameter from 1/16" to 12" in both Basic & Step Limit Design.

DIA IN INCH TPI Type of Thread Gauges used
1/1, 6, 1/8 27 Taper Plug Gauges, L1 Basic
L1 Step Limit
Plain Taper Plugs
to check Taper Bore / Minor Diameter
of Internal Threads.
Taper Ring Gauges L1 Basic
L1 Step Limit
Master Plug/ Check Plugs/ Wear Check
Plugs to check
Ring Gauges.
¼, 3/8 18
½, ¾ 14
1, 1.1/4, 1.1/2, 2 11.5
2.1/2, 3, 3.1/2,4
4, 5, 6, 8,10,12
Rings Diameter above 8" are not in Mfg. Range

NPT L2 gauges to check threads beyond L1 limit, i.e. up to L2 length for wrench fit, can be supplied on request.