PT Notes
Damage Mechanism Reviews
PT Notes is a series of topical technical notes on process safety provided periodically by Primatech for your benefit. Please feel free to provide feedback.
Historically, reliance has been placed on PHA teams to identify initiating events for hazard scenarios using their process knowledge and experience. However, it has become apparent that some equipment damage mechanisms may be overlooked.
A number of process safety incidents have resulted from such causes including the Tesoro refinery fire in Anacortes, WA in 2010 and the Chevron refinery fire in Richmond, CA in 2012. The Division of Occupational Safety and Health within the California Department of Industrial Relations has issued amended process safety management regulations that include a requirement to perform damage mechanism reviews (DMRs) in support of PHA studies for petroleum refineries in California.
DMRs are valuable not only for petroleum refineries in California but also for any facility where equipment failures may result in catastrophic accidents regardless of its geographic location.
A damage mechanism is defined as a mechanical, chemical, physical or other process that results in equipment or material degradation such as embrittlement, stress-corrosion cracking, and sulfidation corrosion. Damage mechanisms may cause the failure of process equipment resulting in loss of containment or impaired operability of equipment. They may cause damage to equipment and materials that contain process fluids such as piping, pumps, and valves; equipment and materials that provide safeguards against process incidents such as fireproofing, dikes, and deluge systems; and equipment and materials in utilities and support systems whose failure may impact on or result in a process safety incident. Damage mechanisms can arise internally or externally, such as from internal or external corrosion.
A DMR should be carried out prior to the performance of a PHA study to identify those damage mechanisms that are believed possible for a process. This information is provided to the PHA team for consideration during a study.
Key items to be addressed by a DMR include:
- Identification of potential damage mechanisms.
- Determination that the materials of construction are appropriate for their application and resistant to potential damage mechanisms.
- Methods to prevent the occurrence of damage mechanisms or mitigate damage that may occur.
- Identification of operating parameters that affect damage mechanisms.
- An assessment of previous experience with damage mechanisms for the process.
- A review of industry-wide experience with the process.
- Identification of applicable standards, codes and practices.
The results of DMRs help to provide more comprehensive identification of hazard scenarios in PHA studies.
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