Discussion on the classification of pressure pipelines for formalin solutions
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Regarding the toxicity of formaldehyde, the \"Classification of Hazards from Occupational Exposure to Toxic Substances\" (GB5044-85) classifies it as a highly hazardous substance. According to the classification system for pressure pipelines, formaldehyde solution pipelines are classified as GC2 category； However, the standard \"Classification of Hazards from Occupational Exposure to Toxic Substances\" (GB5044-85) was repealed on March 23, 2017; it is therefore no longer appropriate to use this standard for assessing the toxicity of substances. Nowadays, the toxicity of substances is generally assessed in accordance with the \"Classification of Hazards from Occupational Exposure to Toxic Substances\" (GBZ 230-2010) and the \"Classification Standards for Toxicity Hazards and Explosion Risks of Chemical Substances in Pressure Vessels\" (HG/T 20660-2017). According to Table 4.0.2 of the \"Standard for Classifying the Toxicity and Explosive Hazard Levels of Chemical Substances in Pressure Vessels\" (HG/T 20660-2017), formaldehyde is classified as an \"extremely hazardous substance\"; this classification is based on the calculations outlined in the \"Standard for Classifying the Hazards of Toxic Substances Exposure at Work\" (GBZ 230-2010). The relevant calculation data can be found in Table A.0.1 of the same standard. Due to changes in the toxicity of formaldehyde, should the classification of pressure pipelines containing formaldehyde solutions be upgraded from “GC2” to “GC1”?
It’s still GC2, because the references in the pressure pipeline inspection regulations haven’t been changed
The standards specify that chemicals are pure substances, while mixtures need to be considered as a whole； For formalin solutions, 37% formalin represents a moderate level of hazard; therefore, GC2 is the appropriate choice
The criterion in GB5044 still holds that human carcinogens are of extremely high hazard. The new pressure pipeline standards now refer to toxicity in terms of acute toxicity, removing the carcinogenicity factor as a hazard; however, GB50316 still classifies fluids based on their degree of hazard, assigning them to Category A1 fluids, which requires 100% testing.