OSHA’s most recent PSM Letter of Interpretation (LOI) confirms their position on covered process battery limits. I struggle with this, as their position states, and I quote, “Neither the application paragraph nor the definition of “process,” states or implies that controls can limit the extent or boundaries of a PSM-covered process.”
With this position, OSHA does not appear to consider “process reactions” where the HHC is reacted within a process vessel, and after the reaction is completed, the product remaining in the vessel is no longer hazardous. Based on this OSHA position, all the interconnect downstream equipment/process would still be within the process battery limits of the PSM-covered process.