A new Hydrogen project involving H2 generation, Storage and Power Generation is under consideration at a major Natural Gas Storage location. This first of a kind plant has some interesting challenges, I would like to highlight my thoughts and open discussion to the community. H2 generation was from a bank of industrial Electrolysers , storage was repurposing an existing deep salt cavern, power generation was from GT H2 compatible. Projects identify one stage 3 assessment ( HAZOP) but this is never enough unless it is a well proven design and is therefore a significant risk to the overall project delivery. Consider several HAZOP and Design reviews (DR). The Electrolyser was an OEM design protection design from machinery directives, but then multiple units were used in combination to generate the capacity required and this is now a process plant with its own dynamics and process safety requirements which need HAZID and HAZOP. These identify new hazards which need design changes to the original ‘machine’, consider a DR following the initial HAZID but the DR can take the form of a HAZOP. The output from the Electrolyser needs compression to store in the salt cavern from atmospheric pressures of the Electrolyser to 250Bar storage pressure introduces significant hazards requiring safety function development. High Pressure H2 need a specialised chock valve to reduce to 30 Bar operational pressure of the GT. The power generated (nominally 50MW) can be used by the existing storage plant therefore having electrical interface and introducing further hazards. The control of the existing storage plant needs integration of the new plant, from cavern management and power utilisation. With so many changes to the existing plant and introduction of new hazards requires a multi-stage HAZOP/DR this is an iterative approach, HAZID, DR, HAZOP, HAZID DR HAZOP….. until a final process can be achieved. In addition, consideration of system flows, not just process flows; we need to expand the Process HAZOP with an Electrical HAZOP and a Control HAZOP, how do these separate systems interact and introduce different hazards?

A new case study has been added to the classroom. Scenario: A SIL 2 reactor feed isolation valve has been proof tested annually for 10 years. Every test has passed. The SIL verification claims 90% proof test coverage. Your task: Determine why the SIF is failing to meet its SIL 2 target. Full case study here: [link] Questions: - What is the first thing you would check in the proof test procedure? - How would you justify a revised coverage figure without retesting? - Would you accept a partial stroke test as a high-coverage test?

A new case study has been added to the classroom. Scenario: A 1998 installed SIS with unknown diagnostic coverage is still in service. The asset owner believes it achieves SIL2 based on vendor documentation. Your task: Determine whether the claim is credible. Full case study here: [link] Questions: • What is the first thing you would check? • How would you deal with missing failure rate data? • Would you accept prior-use evidence?