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OSHA Hazard Information Bulletins
Couplings And Marking Recommendations For Plant Airline Used For Breathing

April 20, 1990




  • Director
  • Office of Field Programs


  • Director
  • Directorate of Technical Support


  • Hazard Information Bulletin - Couplings And Marking Recommendations For Plant Airline Used For Breathing

The Directorate of Technical Support issues Hazard Information Bulletins (HIBs) in accordance with OSHA Instruction CPL 2.65 to provide relevant information regarding unrecognized or misunderstood safety and health hazards, and/or inadequacies of materials, devices, techniques and engineering controls. HIBs are initiated based on information provided by the field staff, studies, reports and concerns expressed by safety and health professionals, employers and the public. Information is compiled based on a comprehensive evaluation of available facts, literature and in coordination with appropriate parties. HIBs do not necessarily reflect OSHA policy.

This bulletin is prompted by a recent incident where an employee at a DOE facility narrowly escaped injury when he accidentally hooked his air manifold and air purifying accessory (APACC) unit into a nitrogen system and was deprived of oxygen long enough to black out. An investigation into this incident indicated that three factors had contributed to the accident: (1) Couplings on the nitrogen lines were identical to those on the plant air system, (2) The nitrogen lines were not properly color coded, and (3) the plant air system was used to supply respirable air.

To help ensure that employees do not inadvertently hook up to gas supplies other than to respirable air, the following guidelines are recommended:

  1. If similar couplings are used for the plant air supply system and other gas delivery systems, replace couplings on gas systems or air supply system with another, unique type of coupling. See CFP 1910.134(d)(3).
  2. Use color coding to identify piping (See the American National Standard Scheme for Identification of Piping Systems ANSI A13.1-1981 for further information).
  3. Develop a maintenance procedure to assure that air supply-lines are properly identified by employees.

Please distribute this bulletin to all area offices, state plan states, and consultation project officers.

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