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MRO Hazardous Material Codes


MRO hazardous materials should be coded according to the risks that they pose. The below nine hazardous materials classifications can be applied across the MRO Material Master.

  • Class 1: Explosives
  • Class 2: Gases
  • Class 3: Flammable liquids
  • Class 4: Flammable solids
  • Class 5: Oxidizers/organic peroxides
  • Class 6: Toxic and infectious substances
  • Class 7: Radioactive material
  • Class 8: Corrosives
  • Class 9: Miscellaneous hazardous materials

Within class 6 are two subclasses:

  • Subclass 6.1- poisonous material
  • Subclass 6.2- infectious substance

A subclass 6.2 infectious substance is defined as a material known or reasonably expected to contain a pathogen. A pathogen is a microorganism that can cause disease in humans or animals.

See examples from our Library of industry-standard MRO Hazardous Material Codes below. 


Code Definition
Class 1 Explosives
Class 2 Gases
Class 3 Flammable Liquids
Class 4 Flammable Solids
Class 5 Oxidizers/organic peroxides
Class 6 Toxic and infectious substances
Class 6.1 Poisonous material
Class 6.2 Infectious substance
Class 7 Radioactive material
Class 8 Corrosives
... ...