Home / Standards / GB/T 20928-2020 GB/T 20928-2020 Active Seamless inner grooved copper tube 无缝内螺纹铜管 Standard Type GBT ICS 77.150.30 CCS H62 Status 现行 Issue Date 2020-09-29 Implementation 2021-08-01 Responsible Dept 中国有色金属工业协会 Drafting Unit N/A