NPT Screw Plug Gauge

S.G. Prittie manufactures a range of NPT screw plug gauges, with many common sizes in stock. Our gauges are step limit type, max. and min. steps provide reliable accurate gauging. All of our gauges are made from hardened tool steel to ensure long life and are supplied with a manufacturers certificate of conformance (COC).

Product options

NATA Calibration – ISO 17025
ESSO and Woodside variations available
Other Nation Pipe types can be ordered
Storage case for a single gauge or for a gauge set

Applicable standards

ANSI B1.20.1
ANSI B1.20.3
ANSI B1.20.5

Why this product is used

Tapered screw plug gauges are an efficient way to check internal thread conformance. Simply screw the gauge into the part by hand until it stops. If the end face of the part is between the max. and min. steps this condition indicates a conforming part.

  • Customisation

    Customisation is offered on most gauges. We can add a new feature to a standard gauge, manufacture a revised design based on a standard gauge, or design a new gauge to suit your application.

  • Support

    We offer design and technical support for all our gauges, as well as support for measurement and calibration inquiries. Contact us via phone or email.

  • Delivery

    We offer express or economy delivery and can send products to local, interstate and overseas locations. We’re also happy to use your own delivery supplier.

  • Manufacturing

    We are an Australian business located in Airport West Victoria. Quality is a priority and we have ISO 9001 and ISO 17025 management systems in place.


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Thread type Range in stock Range manufactured
NPT 1/16” - 4” 1/16” - 6”
NPTF 1/16” - 2” 1/16” - 6”


Can I get gauges to suit ESSO or Woodside tolerances?

Yes, we can make dedicated gauges with only ESSO or Woodside steps or we can add additional steps to standard gauges.

How often do I need to calibrate my gauge?

There is no fixed time, calibration frequency is based on how often the gauge is used and the conditions that the gauge is exposed to. Frequent use and abrasive materials will require more frequent calibration, low use in a clean environment will allow less frequent calibration. Usually the user determines the calibration frequency.

If you need assistance selecting the correct gauge or have technical questions please contact us.

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