This part of GB/T 1149 specifies the basic dimensional characteristics of trapezoidal steel piston rings (hereinafter referred to as trapezoidal steel rings) whose piston ring types are T, TB, TBA, TM, K, KB, KBA and KM. This standard applies to trapezoidal steel rings for reciprocating internal combustion engines with cylinder diameters from 70 mm to 160 mm.