For facilities having to comply with the 1910.119 Process Safety Management (PSM) mandate of 1992, Process Hazard Analyses (PHAs) are required to be revalidated every five years after the initial effort. To refresh your memory, the mandate requires that Process Safety Information (PSI) be compiled and verified as accurate prior to conducting the initial PHA. It follows that PSI shall be revalidated every five years or on a continuous basis to ensure the five-year PHA revalidation effort is performed using the current design and process information. Once again, the PSI for a PHA revalidation shall be compiled and verified as accurate PRIOR to conducting the PHA revalidation.
As a company, we conduct many PHAs every year. Some of these PHAs are initial efforts for projects or new units, but many of them are PHA revalidations of existing units. It is common practice now to meet with the client representative or sponsor at least a month in advance to discuss the status of the PSI needed to conduct the PHA or PHA revalidation. This is the time to challenge the organization regarding the completeness and accuracy of the PSI. Some good questions to ask include:
- How well does your Management of Change (MOC) program work to capture changes to PSI?
- When was the last time a P&ID walkdown was completed and red-lines captured on the CAD file and re-issued?
- How are pressure relief design bases of individual pressure relief devices maintained as changes occur?
- How is the flare/effluent handling system design basis maintained as changes occur?
- Are equipment, vessel, exchanger, and pump files (especially pump curves) up to date and available?
- If changes to pumps or pump impellers have been made, what other changes were captured?
- Is a chemical compatibility matrix available and does it account for new chemicals since the last PHA?
- Have Independent Protection Layers (IPLs) been identified and have Process Safety Times (PSTs) been calculated and verified as acceptable?
- How are check valves and restriction orifices maintained?
- Are car-seals or physical locks used to lock manual valves open or closed and how are they tracked?
These are just a few of the questions we try to ask when conducting the pre-meeting in preparation for the upcoming PHA. If the PSI is found to be inadequate, then the PHA is often postponed until the organization can produce high-integrity PSI. Unfortunately, the client cannot always be persuaded to postpone the PHA or the client is sometimes convinced the PSI is in good shape when in fact it is not. In these situations, we know two things will happen…no doubt about it…and we inform our clients of this upfront to avoid dissatisfaction down the road.
When a group conducts a PHA without high-integrity PSI, (1) the analysis will be incomplete and (2) more recommendations will be generated. Without complete and accurate PSI, it will be difficult to fully develop and assess some hazard scenarios. For example, it is difficult to assess a dead-head situation on a pump without a pump curve for centrifugal pump or a manufacturer’s certification of maximum discharge pressure on a blocked-in condition for reciprocating pumps. It is also difficult to take credit for IPLs, if the associated process safety time for the scenario has not been calculated. I could go on with many more examples we have encountered in real life, such as working with inaccurate P&IDs or discovering missing or incorrect pressure relief device design bases. The incomplete analysis leads to gaps and gaps result in recommendations. More often than not, the PHA team ends up writing recommendations to compile accurate PSI and then reconvene the team to revisit the identified gaps in the analysis. Both of these issues delay and drag out the PHA, which is a drain of time and energy of precious resources. To avoid time delays and potential safety missteps, make sure the PSI is complete and accurate BEFORE attempting the PHA…even for PHA revalidations.