What You Should Know About Our NPTF 6 Step Ring Gages

NPTF 6 Step Ring Gages are used in conjunction with an L1 gage to measure the pitch diameter of a part. The part in question may belong to aeronautical or dry seal parts depending upon its use and application. The use of NPTF 6 Step Rings ensure confirmation of the requirements of the Dryseal while it, itself conforms to the ANSI B22 Standards.

More on NPTF 6 Step Rings:
As the name states, each NPTF 6 Step Ring Gage is divided into 6 different steps which include:
  • B
  • BT
  • MNT
  • MN
  • MXT
  • MX

The crest of the NPTF Ring 6 Step is used for inspecting the truncation limits and the taper of the major diameter. The steps or notches aforementioned are in relation to the position where the L1 gage is measured (may also include L3 or L2).

If a part falls in the minimum range, it must measure between MN and MNT, similarly, if it falls between the basic range, it must measure between the B and BT range. Finally, if it falls in the maximum range, then it must fall between MX and MXT. Besides NPTF, it is also used to measure ANPT for the root-check gage of the threads of the products in measurement.

How To Use:
The three steps (B, MN, MNT) represent the minimum truncation for the basic minimum and maximum thread sizes whereas the other three (BT, MX, and MXT) represent the corresponding maximum truncation. They are used in a fashion similar to the 6 step plain plug, with the only difference being that the ring is always used with an L1 ring gage where the ring is used to confirm whether the thread crest is within the defined specifications.

Difference Between NPT and NPTF:
It is still noteworthy that there is a major difference between the thread design of NPT and NPTF, which is why they both have different requirements spelled out in separate ANSI codes. For National Pipe Taper or NPT threads, their requirements are expressed in ANSI B1.20.1 whereas, for National Pipe Taper Fuel or NPTF, the requirements are expressed in B1.20.3.

What sets both NPT and NPTF apart is the root and crest of their threads along with their major/minor diameters. Besides that, you will find that both NPT and NPTF have the same pitch diameters, taper-per-inch, and even threads-per-inch. So it seems that the NPTF crest lies right where the parameter requirements of NPT lie, with the only difference being a minor range of thread crest.

This is why NPTF requires more assembly and consideration in comparison to NPT. Moreover, the thread roots are also different. They create a mechanical seal when they are tied with the crest of NPTF mating thread at the assembly by deforming, hence earning them the name, dryseal.

NPTF 6 Step Rings ensure closer control and confirmation of the necessary standards to form a satisfactory dry seal. Their essential application is to confirm the three zones of the gage overlapping.

At WESTport, we provide you with quality that you can trust. We are manufacturers who are ISO 6506, ISO 9001 and ISO/IEC 17025 accredited which means each of our products complies with the strictest industrial standards. Ranging from plain and threaded plug and ring gages to any custom need gage to your blueprint specifications, WESTport is your one stop shop for all your quality assurance needs. We are committed in providing premium quality products in a timely manner with our industry guarantee to beat any competitors price.

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