Management of Change (MOC): Process Safety Review and Approval

Overview

A seemingly small change to equipment, chemical service, software, operating procedure or temporary bypass can alter the plant's hazard profile. A robust MOC identifies the proposed change and technical basis, evaluates impacts on process and worker safety, updates drawings and procedures, secures competent approvals and communicates changed controls before use. US OSHA PSM requirements at 1910.119(l) apply to covered processes; projects outside that scope must follow their governing legal and contractual system. This guide supports review rather than granting permission to make a change.

Main Hazards

• • Temporary bypass of an interlock or protective device without risk acceptance
• • Change in process fluid, pressure or operating sequence not reflected in hazard analysis
• • Changed piping or electrical connection not reflected on P&IDs
• • Maintenance crews unaware of revised isolation boundaries
• • Temporary change retained indefinitely without review
• • Unapproved return to service following a change

Essential Controls

1. 1Document change scope, initiating reason, affected equipment and the intended operating period.
2. 2Identify applicable technical, process, maintenance, HSE and operational reviewers.
3. 3Evaluate consequences for safeguards, compatibility, isolation, alarms and emergency response.
4. 4Define approval and authorization criteria before field implementation.
5. 5Update affected P&IDs, operating documents, permits and training materials.
6. 6Communicate the change to affected employees and contractors before start-up.
7. 7Track temporary-change expiry and verify reinstatement or formal permanent conversion.

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