NPTF / PTF Thread Gauges

NPTF THREADS can provide pressure tight seal on threads without use of a sealing compunt (Dry Seal Type). They are used in pipe assemblies where without using sealing compound pressure tight joint is required on threads.

PTF Threads are similar to NPTF but short in length. PTF threads are used in applications similar to NPTF.

Specification:

ANSI/ ASME B1.20.3 : 1976 & ANSI B1.20.5 : 1996 & American Handbook H-28 Part II : 1957.

Manufacturing Range :

Taper Thread Plugs L1 & L3 in both Basic & Step Limit Design, Plain Taper Plugs to check crest of Threads, Taper Thread Rings L1 & L2 in both Basic & Step Limit Design, Plain Taper Rings to check crest of external threads (6 step design), Master Check Plugs to check Thread Rings L1 & L2.
Pipe Sizes covered are from 1/16" to 3"

DIA IN INCH	TPI	Type of Thread Gauges used
1/16, 1/8	27	Taper Plug Gauges L1 Basic L3 Basic OR L1 Step Limit L3 Step Limit	Plain Taper Plugsto check Crest of Threads.	Taper Ring Gauges L1 Basic L2 Basic OR L1 Step Limit L 2 Step Limit	Check Plugs / Master Plugsto check L1 & L2 Taper Rings.	Crest CheckPlain Taper Ring Gauge.6 Step Design.
¼, ⅜	18
½, ¾	14
1, 1.1/4,1.1/2,  2	11.5
2.1/2, 3	8

For Internal Threads (Thread Plug Gauges) two types are recommended. L1 – To check effective diameter of thread to hand tightness at the gauge line (large end dia.) L3 – To check effective dia. of remaining thread length (small end dia.) and the taper cone.

For External threads (Thread Ring Gauges) two types are recommended. L1 – To check effective diameter of thread to hand tightness at the gauge line (large end dia.) L2 – To check effective dia. of remaining thread length(small end dia.) and the taper of cone.

Normally L2 rings and L3 plugs are used in addition to L1 gauges, where more stringent, examination is required.
The use of L2 and L3 gauges is only effective when the designed full thread length in the work piece is one thread longer than the nominal thread length.