Management of Change (MOC) and Pre-Startup Safety Review (PSSR) are two closely related but distinct processes within process safety management. Organizations frequently confuse the two or treat them as a single process, which can lead to gaps in safety verification and regulatory non-compliance. This guide explains what each process does, how they differ, and how MOC software automates both to ensure nothing falls through the cracks.
MOC and PSSR at a Glance
Management of Change (MOC)
Purpose: Evaluate, approve, and document a proposed change before implementation
Timing: Before the change is made
Key question: “Should we make this change, and what safeguards are needed?”
- Identifies hazards and risks
- Evaluates impact on safety, health, and environment
- Determines required approvals and actions
- Documents the basis for the change
Pre-Startup Safety Review (PSSR)
Purpose: Verify that all requirements are satisfied before the change goes live
Timing: After the change is built but before startup
Key question: “Are we ready to start up safely?”
- Confirms construction matches design specs
- Verifies procedures are updated and adequate
- Ensures training is complete
- Validates all MOC action items are closed
What is Management of Change (MOC)?
MOC is a structured process for proactively identifying, assessing, and managing changes within an organization. Under OSHA’s PSM standard (29 CFR 1910.119(l)), employers must establish and implement written procedures to manage changes to process chemicals, technology, equipment, and procedures.
The MOC Process Covers
- The technical basis for the proposed change
- Impact of the change on safety and health
- Modifications to operating procedures
- Necessary time period for the change
- Authorization requirements
- Notification and training of affected employees
- Updates to process safety information
For a deeper look at what triggers an MOC and how the process works, see How MOC Software Works.
What is a Pre-Startup Safety Review (PSSR)?
PSSR is a verification step that takes place after a change has been designed and constructed but before the modified process or equipment is put into service. Under OSHA PSM (29 CFR 1910.119(i)), a pre-startup safety review must confirm that:
PSSR Checklist Requirements
- Construction and equipment are in accordance with design specifications
- Safety, operating, maintenance, and emergency procedures are in place and are adequate
- A process hazard analysis has been performed for new facilities and recommendations have been resolved or implemented
- Training of each employee involved in operating a process has been completed
- All MOC requirements have been met before startup
When is a PSSR Required?
Not every MOC requires a PSSR, but every PSSR should be linked to an MOC (or a new facility commissioning). Under OSHA PSM, a PSSR is required for:
PSSR Triggers
- New facilities that will handle highly hazardous chemicals
- Modified facilities when the modification necessitates a change in process safety information
- Modified facilities that are significant enough to require a change in the process hazard analysis
Low-risk changes—such as replacing a component with an identical part (replacement-in-kind)—typically do not require a PSSR because they do not alter the process.
How MOC Software Connects MOC and PSSR
Ecesis MOC software treats MOC and PSSR as connected stages of the same workflow rather than separate processes. This eliminates the coordination gaps that lead to incomplete safety verification.
Automatic PSSR Triggering
Based on risk assessment responses and the scope of the change, the software automatically determines whether a PSSR is required and adds it to the workflow. There is no need for manual tracking or separate checklists.
Integrated Task Tracking
PSSR checklist items are tracked alongside MOC action items in a single system. Reviewers can verify that training is complete, procedures are updated, and construction matches specifications—all within the same change request.
Closure Prevention
The MOC cannot be closed until all PSSR requirements are satisfactorily completed. This prevents premature startup and ensures a complete audit trail linking the original change request to its final safety verification.
Post-Startup Reviews
For changes that require ongoing verification after startup, the software can also trigger post-startup review tasks to validate that the change is performing as expected and that no new hazards have emerged.
Common Mistakes with MOC and PSSR
For more on avoiding these and other pitfalls, see our guide on common MOC failures and how to avoid them.
Ecesis EHS Software Solutions
MOC Software
Automated workflows, risk assessments, and change control
Process Safety Management
Comprehensive PSM compliance and documentation
Hazard Analysis
PHA, JSA, and risk assessment tools
Inspection Software
Mobile inspections, checklists, and audit tracking
Incident Management
Incident reporting, investigation, and corrective actions
Training Management
Track certifications, competency, and compliance training
