Definition:
A Mechanical Integrity (MI) Program is a structured set of practices used to ensure that critical process equipment is designed, installed, inspected, tested, and maintained so it can perform its intended function safely over its lifecycle. The term originates from the U.S. Process Safety Management (PSM) and EPA Risk Management Program (RMP) regulations, where mechanical integrity is a formal compliance requirement.
While an MI program is not defined directly in IEC 61511, the standard clearly requires that a SIS and its components be properly maintained, tested, and managed to sustain the required safety performance. In practice, MI programs and functional safety maintenance requirements are closely related and often implemented together.
Key Points:
- Mechanical Integrity originates from OSHA PSM (29 CFR 1910.119(j)) and EPA RMP (40 CFR 68.73).
- Typical equipment within scope includes pressure vessels, piping, relief devices, valves, instrumentation, and rotating equipment.
- MI programs rely heavily on the following industry standards:
- API 510 – Pressure Vessel Inspection Code
- API 570 – Piping Inspection Code
- API 653 – Tank Inspection, Repair, Alteration, and Reconstruction
- API 576 – Inspection of Pressure-Relieving Devices
- MI programs are not functional safety programs, but they strongly influence the reliability assumptions used in safety analyses.
Example:
A facility’s Functional Safety Management (FSM) procedures explicitly reference its MI program as the means for maintaining the mechanical equipment relied upon by safety instrumented functions. The FSM procedure further cites API 570 for process piping and API 576 for pressure relief valves.
Cited Source:
- OSHA – PSM Program – 29 CFR 1910.119(j):
- EPA – RMP Program – 40 CFR 68.73
- API 570
- API 510