Temporary changes, including bypasses, jumpers, defeated instruments, and other short-duration deviations from design intent, are explicitly required to follow the MOC process under 29 CFR 1910.119(l). OSHA has been clear that the word temporary describes the intended duration of the change, not a reduced level of hazard review. Many of the worst process safety incidents have involved temporary changes that became permanent through neglect, or that were made without authorization. These letters address what constitutes a temporary change, the documentation required, time limits, and what happens when a temporary change outlives its authorization.

What OSHA Has Said

Jan 11, 1996
Temporary Change Authorization and Time Limits
OSHA addresses whether temporary changes require the same documentation and hazard analysis as permanent changes. They do. Temporary changes must include a defined end date and review process, and must go through full MOC if extended.
Read OSHA Letter ↗
Jun 23, 2023
Bypass and Inhibit Practices as MOC-Triggering Changes
OSHA addresses the practice of bypassing safety instrumented system functions and analog instrument loops. Repeated or extended bypasses require MOC treatment even if individual instances are brief.
Read OSHA Letter ↗
Dec 7, 1995
Defeating Interlocks and Safety Devices and MOC Requirements
Early OSHA guidance establishing that disabling, defeating, or bypassing process safety devices, even temporarily for maintenance, is a change to the process and triggers MOC requirements.
Read OSHA Letter ↗

⚡ Key Compliance Takeaway

Temporary changes require full MOC treatment. Set a hard expiration date, document the hazard review, and ensure operators are informed. If a temporary change has been in place for more than a few weeks, treat it as permanent and reopen the MOC process.