At this point in the project lifecycle, all of the equipment is specified and ordered. Construction of the plant is then completed and off-site testing (FATFactory Acceptance Test) carried out on process control and safety instrumented systems.

Design changes are very expensive at this stage so they should be avoided where possible. However, any changes which are required at this stage must be fully risk assessed to ensure that the HazOp Hazard & Operability Study is still valid – i.e. did the design change remove a safeguard claimed in the HazOp, or did it make a safeguard ineffective?

The process safety focus at this stage is on ensuring that actions from the previous hazard studies have been completed and that the system is safe to start up. Some form of PSSR Pre-Start Up Safety Review / HS4 Hazard Study 4 should be carried out at the point of handover from the construction team to the commissioning team. These pre-commissioning studies are called different things in different companies or industries, but in essence, they are all intended to answer the question “is it safe to start up the plant?”. The PSSR / HS4 involves a group exercise to establish if all of the pre-commissioning actions have been completed. This may include safety critical actions from the HazOp, satisfactory FAT completion, appropriate training/plant awareness complete etc.

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Technical author

David Sparkes

Technical Director, Method Process Safety

David is an experienced process engineer with a solid background in plant support, capital projects and control system design.

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