Scottish & Southern Energy (SSE) recognised the need to carry out detailed process safety risk assessments at their Peterhead power station.
They wanted to identify potential hazardous events and assess the adequacy and robustness of their risk reduction measures. This information and the associated action plan has provided a platform for improvement across the power station and helps with development of key risk control procedures within the Process Safety Management (PSM) system. A major concern was the time required using a familiar technique such as HAZOP and the fact that busy operations staff would need to be heavily involved.
SSE talked to ABB Engineering Services about their unique Process Hazard Review (PHR) technique that was developed for the rapid assessment of process safety hazards on existing plants. PHR has been used extensively on plants throughout the process
industries and particularly in recent years for sites coming under the COMAH regulations. It provides a detailed yet high level assessment of the whole process, focussing on areas of concern and helping to demonstrate continuous improvement in process
safety.
ABB provided a PHR leader and a consultant 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 scoping meeting explored the nature of process safety hazards on the site and identified shortfalls in the overall management arrangements.
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 were 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 were 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.
SSE is now working through a prioritised action plan for the Peterhead site that will provide an assurance that process safety risks are under control.