How to Use NPTF Master Thread Plugs

NPTF, or National Pipe Taper Fuel master thread plugs are designed to check the compliance of a thread in a product. By using these hand-held gauges, you can determine if the thread is the correct size, and if the fastening device engages the thread properly. NPTF gauge testing compliance checks whether two mating threads from fastening hardware, and things like handrails and other building supplies, form a satisfactory dry seal without additional sealing compounds. The NPTF plug gauge tool allows for quick checks, accommodating a range of thread sizes in a compact size.

Things You'll Need

• NPTF threaded inserts
• NPTF handle assembly

Instructions

1. Insert the correct threaded insert into the handle for the thread gauge you are testing. Tighten the screw recessed into the handle with the included key to tighten the insert in place.

2. Note the notches or shaved threads on the insert. This indicates the minimum thread penetration depth required for go/no-go testing.

3. Rotate the threaded insert into the threads on the product you are testing. One full turn in either direction (+1/-1) indicates acceptable compliance.

Tips & Warnings

• The difference between NPT and NPTF is that NPTF does not require Teflon tape or other thread wrapping dope material.

References

• The Gage Store: How to Use NPT Thread Gages
• Green Slade and Company: Gaging NPTF Threads