Technical Progress in Chinese Standard of Classification on Hazard of Medium in Pressure Equipment

Abstract The classification on hazard of medium plays a crucial role in ensuring the safety of pressure equipment. In China, pressure vessels are classified by design pressure, volume, and medium groups according to TSG 21-2016 Supervision Regulation on Safety Technology for Stationary Pressure Vessel, where medium - related factors are closely linked to vessel design, manufacture, and inspection. The Globally Harmonized System (GHS) provides a global standard for chemical hazard classification, while China has its own medium standards like HG 20660-2000 Classification for Toxicity and Explosiveness of Chemical Medium in Pressure Vessels as the cited standard for pressure vessel use now. HG 20660 was revised and promulgated in 2017 based on GBZ/T 230-2010 Classification for hazards of occupational exposure to toxicant. The revision leads to increases of toxicity hazard level for some mediums, resulting in construction cost hikes and other problems if to be cited and used in the future. To address these issues, China issued a new national standard, GB/T 42594-2023 Guidelines for classification on hazard of medium in pressure equipment. This paper summarizes the special requirements for pressure vessels with hazardous chemicals. Then it introduces the concept and main content of GB/T 42594-2023, and analyzes the changes and impacts of the new standard on medium classification. The comparison among different standards shows that GB/T 42594-2023 not only aligns with international practices but also offers more comprehensive and practical solutions for pressure equipment in China.