Standards for decompression chambers for use with pressurized face-tunnel boring machines.

OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

July 23, 2010

Letter #20100303-9658

Re: Standards for decompression chambers for use with pressurized face-tunnel boring machines.

This letter responds to your question of February 9, 2010, to Richard S. Terrill, Administrator of OSHA Region X.

Question:  Are pressure vessels for human occupancy involved in tunnel boring required to be fabricated and documented in accord with the ASME PVHO-1 standard, "Pressure Vessels for Human Occupancy"?