December 13, 1990

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.

On May 20, 1988, the Directorate of Technical Support issued a safety hazard information bulletin on the use of polyvinyl chloride (PVC) plastic pipe for transporting compressed gases in above ground installations. We pointed out that the Plastics Pipe Institute (PPI), in its Recommendation B dated January 19, 1972, recommended against the use of thermoplastic pipe for transporting compressed gases in above ground plant piping installations unless the thermoplastic pipe were properly encased.

The Seattle Regional Office has brought to our attention that another type of thermoplastic pipe, namely impact resistant acrylonitrile-butadiene-styrene (ABS) pipe, resists shatter-type failures under known sizing, pressure and environmental conditions.

The Plastics Pipe Institute has revised its Recommendation B as of December 1, 1989, and recommends that piping need not be buried or encased with shatter-proof materials if the piping has been manufactured from materials which will resist shatter-type failures under anticipated conditions. The determination of a material's failure by shattering involves not only the nature of the material, but also the consideration of in-use pressure, pipe and fitting dimensions, and the nature of the gas. Therefore, above ground piping for compressed gases must conform with the pipe manufacturer's specifications and limitations for proper use and must be designed based on a thorough evaluation of the system.

Please disseminate this bulletin to all Area Offices, State Plan States and Consultation Projects.