GB/T 9253-2022 specifies the processing, measurement and inspection requirements for connecting threads (i.e. API threads) of line pipes, round threaded bushings, round threaded YouTube and partial trapezoidal threaded bushings used in the oil and gas industry. The standard specifies in detail the dimensions, tolerances, marking requirements of API threads and gauges, as well as the instruments and methods used for inspection of these threads and gauges. This standard applies to the use of gauges for controlling thread acceptance, including individual parameter gauges and associated testing instruments. Miscellaneous standards are cited in the standard, including GB/T 23512 on the evaluation and testing requirements of thread grease for the oil and gas industry, and GB/T 27025 on the general requirements for the ability of testing and calibrating laboratories.