Tapered threads are a signature feature of API Tubing & Casing connections. Measuring thread taper is not only an industry wide practice, it is an API Specification 5B mandated inspection. During the manufacturing process, taper must be accurately measured and quantified to stay within the required specification limits. When subjected to a service load, taper error on threaded tubing and casing connections can lead to galling, improper fit, and reduced performance.
Internal Thread (4 1/2 in.and larger)
The taper of internalthreads in sizes 41/2 in. (114.3 mm) and larger shall be measured with an internal taper gauge as illustrated as below:
Internal Thread ( Small than 4 1/2 in)
The taper of internal threads in sizes small than 4-1/2 in. (114.3 mm) shall be measured with an internal thread taper gauge as illustrated as below:
| P/N | Model | Measuring Range | Travel | Resolution |
| Int0106 | JZN06 | 1～6in, Internal Taper | 0～1in | 0.001in |
| Int5516 | JZN16 | 5 1/2~16in, Internal Taper | 0～1in | 0.001in |
| Int0105 | JZN05 | 1~5in, Internal Taper | 0～1in | 0.001in |
| Int0106 | JZN06Z | 1～6in, Internal Taper | 0～1in | 0.0005in |
For more information click the links below:
Taper Measurements-External Taper Gauges
Oil Pipe Internal Thread Taper Gages
How do you use an internal thread taper gauge?