GB/T 33817-2026Method for the determination of the carbon film and carbon content on the inner surface of copper and copper alloy tubes (English PDF)

3 Terms and definitions

4 Qualitative analysis of the carbon film on the internal surface

5 Determination of the carbon content on the internal surface

Foreword

This document was issued on 25 May 2026 by the State Administration for Market Regulation and the Standardization Administration of the People's Republic of China, and takes effect on 1 December 2026.

It replaces GB/T 33817-2017, which remains in force until that date.

The document is under the responsibility of the China Nonferrous Metals Industry Association.

Classification: ICS 77.120.99, CCS H 13.

3 Classification and status

GB/T 33817-2026 is classified under ICS 77.120.99, in the field of metallurgy. ICS is the International Classification for Standards, the same scheme used by ISO and by the national bodies of most countries, which is what allows a Chinese standard to be placed beside its foreign counterparts on subject rather than on number.

Its Chinese Standard Classification code is CCS H 13. CCS is the domestic scheme, a letter for the sector and two digits for the subject within it, and it is the code by which the standard is filed and searched in China.

The GB/T prefix marks a recommended national standard. It is not, in itself, law: it becomes binding when a contract names it, when a regulation or a mandatory standard refers to it, or when a producer declares conformity with it. In practice that covers most of the cases in which it will be read — a purchase specification, an inspection agreement or a certification scheme.

The document is under the responsibility of the China Nonferrous Metals Industry Association, which is the body that maintains it and that will answer a formal question about its interpretation.