The oil and gas industry relies on tapered thread gauges in many situations, such as attaching drill components and securing well head casings. These must have tight tolerances to ensure there are no failures which could potentially lead to leaks or accidents, with associated environmental and economic costs.
The calibration of gauges is carried out via a hierarchy of gauges from the grand master gauge, held by NIST, through regional and reference master gauges, and all thread gauges must be compliant. Gauge manufacturers need to have their gauges calibrated before use and they may need recalibration by the operators during service. NPL is a regional gauge calibrator and works with manufacturers and operators.
A manufacturing company supplying the oil and gas industry was having difficulty exporting some reference master gauges to Asia due to problems with demonstrating compliance, so they came to NPL for help.
NPL is the authorised UK and European agency for the calibration and certification of reference master gauges conforming to American Petroleum Institute (API) specifications, used by suppliers to the oil industry. NPL scientists, in the Engineering Measurement Service team have been providing support to the oil and gas industry for nearly 90 years, by measuring the dimensions of reference master gauges, with either parallel or tapered threads to check conformance with specification. These gauges are part of a hierarchy of gauges ultimately used to check drill and pipeline connectors.
In 1989, a Euromet agreement (137) resulted in NPL being the sole laboratory responsible for the testing of API gauges throughout Europe with LNE and PTB redirecting customers to NPL, and NPL was instrumental in reinstating the API gauging sub-committee.