Execution Failures: The Main Cause of PSM Loss-of-Containment

Last week's article, What Does "Good" Actually Look Like in Inspection?, focused on reducing uncertainty by performing a reasonable inspection and writing a concise report. Out of those reports come recommendations for:

• Repairs
• Replacements
• Re-inspections

This week, our discussion is about what happens when we don't execute them promptly.

The majority of Process Safety Management (PSM) loss-of-containment (LOC) events are attributable to execution failures rather than gaps in technical knowledge. In many incidents, degradation mechanisms were well understood, inspection requirements were defined, and corrective actions were identified; however, inspections were deferred, repairs were delayed, or equipment replacement decisions were avoided, allowing known damage to progress to failure.

Investigations conducted by the U.S. Chemical Safety and Hazard Investigation Board (CSB) consistently identify deficiencies in mechanical integrity execution, including inadequate inspection practices, deferred maintenance, failure to replace aging or damaged equipment, and insufficient follow-through on identified hazards, as recurring causal factors in major chemical accidents. CSB findings emphasize that loss-of-containment events frequently occur when organizations continue operating equipment despite known degradation, often due to production pressures, risk normalization, or ineffective management systems rather than a lack of engineering understanding ⁽²⁾.

This pattern is reinforced by landmark investigations, such as the BP Texas City refinery explosion, in which prolonged deferred maintenance, aging equipment, and failure to act on known integrity concerns were identified as fundamental contributors to the incident. The CSB concluded that the accident was rooted in systemic breakdowns in PSM execution, particularly in mechanical integrity and management decision-making, rather than in an unforeseen technical failure ⁽³⁾.

Industry guidance and performance metrics further support this conclusion. The American Petroleum Institute's Recommended Practice 754 (RP 754) indicates that unaddressed mechanical integrity issues, including overdue inspections, unresolved inspection findings, and delayed repairs, frequently precede Tier 1 and Tier 2 Process Safety Events. These indicators reflect execution weaknesses within inspection, maintenance, and asset lifecycle management processes rather than deficiencies in hazard identification or design standards ⁽⁴⁾.

Collectively, these findings demonstrate that most PSM LOC events are preventable through disciplined execution of existing inspection programs, timely corrective action, and decisive equipment replacement when integrity limits are reached. Improving outcomes, therefore, depends less on new analytical tools and more on organizational accountability, robust MI governance, and consistent follow-through on known risks.

I invite the industry to have this conversation. Comments, criticisms, and discussion are welcome here. Comment below, join the conversation on LinkedIn, or contact me directly. I am excited to hear your thoughts.

REFERENCES

1. U.S. Chemical Safety and Hazard Investigation Board (CSB). February 6, 2017. Preventive Maintenance and Mechanical Integrity Recommendations. https://www.csb.gov/recommendations/preventive-maintenances/.
2. U.S. Chemical Safety and Hazard Investigation Board (CSB). Investigation Reports Related to Maintenance and Mechanical Integrity Failures. https://www.csb.gov/investigations/.
3. U.S. Chemical Safety and Hazard Investigation Board (CSB). March 20, 2007. Final Investigation Report: BP America Refinery Explosion and Fire (Texas City), 2007. https://www.csb.gov/assets/1/20/csbfinalreportbp.pdf.
4. American Petroleum Institute (API). August 10, 2021. API RP 754: Process Safety Performance Indicators for the Refining and Petrochemical Industries. https://www.apiwebstore.org/standards/754.

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