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UN Series Thread Gages

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Besides API gauges, Shanghai Jingoo Petroleum Apparatus Co., Ltd. carries a wide range of standard gauges as well, so that we can meet all the requirements from our customers.


The specific categories we offer are as below:

● UN Series Thread Gages

● Metric Series Thread Gages

● National Pipe Thread Gages

● ACME Screw Thread Gages


The function of Work Thread Plugs, Thread Rings and Thread Setting Plugs is to inspect the Pitch Diameter and the Functional Thread, and to ensure the proper assembly of the product parts. Unified Inch standard gages are manufactured per ASME B1.2. Metric series thread gages are manufactured per ASME B1.16M / ISO 1502. Pipe Gages (NPT) are manufactured per ASME B1.20.1, ASME B1.20.5. ACME gages and other custom thread gages are also available with us.


Basic use of Go/NoGo Thread Plugs & Rings (UN and Metric series): Using thread gages is very simple. If the Go thread plug goes into the threaded hole and the NoGo does not, then the product is usually considered as within the tolerance limits and acceptable. The inverse is true for ring gages. In some cases of how to judge if the product is not good using the NoGo gage, confusion and questions may arise. As stated in ANSI/ASME B1.2-1983, the "no go (Lo) functional diameter is acceptable when the no go (Lo) thread ring gage applied to the product external thread does not pass over the thread more than three complete turns." Do not force the gage on to the product and on thin-walled parts.


Product features:

● NIST/NIM traceable

● Tool steel, Rockwell C60-63

● Calibration certificate provided