A pre-startup safety review is required before any newly installed or modified process is introduced with a highly hazardous chemical. The triggering question is whether the change is significant enough to require a PSSR, or whether it was covered by the MOC process and does not constitute a startup. OSHA has addressed the distinction between a PSSR following a plant modification and a restart following a planned or unplanned shutdown, the requirement to conduct PSSR before HHC introduction not before mechanical completion, and what constitutes a new process requiring PSSR.

What OSHA Has Said

Jan 30, 2001
PSSR Trigger and Modification vs. Restart After Shutdown
OSHA distinguishes between a PSSR required after a significant modification and a restart following a planned shutdown for maintenance. Routine restarts after planned maintenance turnarounds do not require PSSR unless modifications were made during the turnaround.
Read OSHA Letter ↗
Feb 7, 1996
What Constitutes a New Process Requiring PSSR
OSHA addresses whether a process that has been operating for years but has never received a formal PSSR must have one. Any subsequent modification triggers PSSR before HHC introduction.
Read OSHA Letter ↗
Feb 15, 1994
PSSR Timing and Before HHC Introduction Not Mechanical Completion
OSHA confirms that the PSSR must be completed before highly hazardous chemicals are introduced into the process, not at mechanical completion. Commissioning activities without HHCs do not require PSSR but HHC introduction does.
Read OSHA Letter ↗

⚡ Key Compliance Takeaway

PSSR is a pre-HHC-introduction requirement. Plan PSSR into your turnaround and construction schedules so that all checklist items are confirmed complete before the first HHC enters the new or modified system. Do not mistake mechanical completion for PSSR completion.