ABB provided a PHR leader and scribe to work with a team of SSE staff over a 4 week period covering all process systems on the Peterhead site. The SSE team consisted of knowledgeable operations and technical staff with day-to-day experience of the systems under review and a wider understanding of standards at Peterhead.
Following an initial site tour to gain an understanding of the scale of operations, a team scope meeting explored the nature of process safety hazards on the site and identified shortfalls in the overall management arrangements. For example, a concern was raised over the standard of the process piping and instrumentation diagrams. These drawings are an essential element of process safety information and a recommendation was raised to update the existing drawings to ‘as-built’.
The main part of the PHR involved a structured review of each process system on the power station, starting with the high pressure gas supply. A set of guide words was used to help the team identify credible ways in which hazardous events could occur, mostly related to loss of containment or sudden release of energy. For each event the severity of the possible consequences was assessed, considering harm to people, the environment or damage to SSE assets / reputation. The full range of measures to prevent, control and mitigate each event were then assessed to ensure that they are robust and fit for purpose. This stage gave the opportunity to identify any key concerns with the existing layers of protection and make recommendations for improvement.
Each scenario identified on the PHR was rated for severity and likelihood using the SSE standard word models and risk matrix calibrated to SSE corporate tolerability of risk criteria.
This helped to prioritise the recommendations raised by the team, with 1 scenario rated ‘very high’ risk, 61 at ‘high’ risk, 214 at ‘medium’ risk, and 81 at ‘low’ risk. High risk issues were raised on the following systems reflecting the high hazard potential:
- Gas supply and pressure reducing station
- Heavy fuel oil receipt from jetty and circulation
- Fuel gas supply to gas turbines
- Hydraulic and lube oil systems
- Steam raising systems and steam turbines
- Fuel gas and oil burner systems
- Hydrogen system
- Demin treatment chemicals
- Site transformers and LV/HV switch rooms
SSE is now working through a prioritised action plan for the Peterhead site that will provide an assurance that process safety risks are under suitable control.