Home / Standards / GB/T 1149.12-2013 GB/T 1149.12-2013 Abolished Internal combustion engines―Piston rings―Part 12: Half keystone rings made of steel 内燃机 活塞环 第12部分:楔形钢环 Standard Type GBT ICS 27.020 CCS J92 Status 废止 Issue Date 2013-12-31 Implementation 2014-10-01 Responsible Dept 中国机械工业联合会 Drafting Unit N/A