Tapered Screw Ring Gauge

S.G. Prittie manufactures a large range of tapered screw plug gauges to International Standards. Most of these gauges are used for checking pipe threads including drill rods. Standard thread forms such as ISO 7 (R series) and are NPT kept in stock. Other tapered screw ring gauges can be made to order. 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
Design service for special applications
Storage case for a single gauge or for a gauge set

Applicable standards

ISO 7,   AS 2473,
EN 10226,   ANSI B1.20.1,
ANSI B1.20.3,   DIN 477,
DIN 158

Why this product is used

Tapered screw ring gauges are an efficient way to check external 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
ISO 7 - R Series (BSPT) 1/8” - 3” 1/8” - 6”
NPT and NPTF 1/16” - 4” 1/16” - 6”
NGT 3/4” - 1” 1/8” - 1 1/2”
Valves – Gas cylinders 1.0 0.60 – 1.25
Drill Rod Up to 6”


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.

Is BSPT still a current standard?

No, the current standard is ISO 7.

BSPT was replaced by AS1722 Part 1, then AS1722 Part 1 was replaced by ISO 7.

Is AS1722 Part 1 the same as ISO 7?

It is very close but there are some variations.

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

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