Process Safety Studies Across the Lifecycle of a MAH Facility
From concept to commissioning, each phase of a new build major accident hazard (MAH) facility requires targeted process safety studies. Understanding what to do, when, and why is key to effective risk reduction.
Concept Phase
During the concept phase, data is sparse - often limited to site constraints, broad process outlines, and high-level flow diagrams. Here, Hazard Identification (HAZID) workshops help pinpoint critical hazards early, prompting design changes that can eliminate or reduce risk. The questions to answer at this stage are: “Which major hazards might be inherent in this concept?” and “Can we adopt inherently safer design strategies?” Even a rudimentary consequence review may guide decisions on facility layout or choice of materials. The emphasis is on preventing serious issues before they become embedded in the design.
Design Phase
As the design matures—complete with piping and instrumentation diagrams (P&IDs) and equipment specs—more robust studies come into play. A Hazard and Operability (HAZOP) study systematically examines every segment of the process to identify deviations and potential consequences. Where high-risk scenarios are identified, a Layers of Protection Analysis (LOPA) is often performed to confirm if current safeguards (e.g. relief valves, interlocks) are sufficient, or if extra layers of protection are necessary. Quantitative Risk Assessments (QRA) may also be performed to ensure compliance with regulatory risk criteria. Key questions include: “Have we addressed all deviations?” and “Are safeguards adequate to reduce risk to ALARP (As Low As Reasonably Practicable)?”
Construction & Commissioning
Once equipment arrives on-site and commissioning begins, the safety focus shifts to Simultaneous Operations (SIMOPS) reviews. These studies look at how tasks like construction work, crane lifts, or testing can intersect, potentially creating unforeseen risks. Additionally, a Pre-Startup Safety Review (PSSR) confirms that safety-critical systems—alarms, shutdowns, fire protection—are installed, tested, and ready for hazardous substances. The central questions here are: “Have we implemented all design-phase recommendations?” and “Do we have the right controls to handle the real-world complexity of start-up?”
Operational Phase
During steady-state operation, risks can evolve with process changes, plant ageing, or unexpected failures. Therefore, it’s vital to periodically revalidate earlier studies. A re-HAZOP every few years, or after significant modifications, helps catch new risks. Management of Change (MOC) ensures that any engineering or procedural changes undergo hazard assessment before implementation. In addition, ongoing inspections and performance reviews verify that safety layers—such as emergency shutdown systems or relief valves—remain effective. The guiding questions here are: “Are we still operating within safe bounds?” and “Do we need to update or enhance our safeguards?”
