UPDATED on 5/31/11 to answer some specific questions I received over the holiday weekend…Scenario: A process that is covered under PSM/RMP (a toxic liquefied gas under pressure) is in very close proximity to a propane system that is used solely as an on-site fuel. The propane system had always been exempted using the PSM exemption of materials used solely as a fuel and the Fuels Regulatory Relief Act under RMP.