Primatech

PHA studies may suffer from omissions in covering regulatory or company PHA requirements and deficiencies in covering technical PHA requirements. Knowledge of common omissions and deficiencies can help to prevent them in future studies, including updates and revalidations. Do your studies suffer from any of the following examples of omissions and deficiencies?

Omissions

• Incomplete consideration of design intent and deviations from it, e.g. the same set of a few parameters is used for all nodes in HAZOP studies.
  
  
• No / incomplete treatment of human factors.
  
  
• No / incomplete treatment of facility siting.
  
  
• Previous incidents and near misses were not included.
  
  
• A qualitative evaluation of a range of the possible safety and health effects of failure of controls (risk ranking or equivalent) was not made.
  
  
• An inappropriate PHA method was used, e.g. What If when HAZOP was really needed.
  
  
• Operating modes other than normal / steady-state were not studied.
  
  
• Important operating modes were not considered, e.g. startup, shutdown, emergency shutdown, turnarounds.
  
  
• Process safety information (PSI) and other process data used in the PHA was incomplete or inaccurate, e.g. P&IDs not up-to-date; no plot plan.
  
  
• The PHA study was not properly documented, e.g. hazard scenarios were recorded only when recommendations for risk reduction were deemed necessary.
  
  
• Qualifications of the PHA team leader or team were inadequate, e.g. the team leader was not trained or certified; reliance was placed on new hires as team members.
  
  
• The PHA team was too small to provide the needed technical expertise and process knowledge.
  
  
• PHAs are not performed on the required schedule, e.g. revalidations are overdue.
  
  
• No management system for follow-up on PHA recommendations.
  
  
• Recommendations from the previous PHA were not resolved properly.
  
  
• Resolutions of recommendations were not documented.
  
  
• Open recommendations exist from the previous PHA.

Deficiencies

• Process subdivision is not appropriate and/or not adequately documented, e.g. nodes are too large to enable the full identification of hazard scenarios.
  
  
• No / incomplete treatment of external events, e.g. flooding, low temperatures and other natech events.
  
  
• Multiple failures were not treated, e.g. concurrent human failures.
  
  
• Common cause failures were not addressed, e.g. between the basic process control system and safety instrumented systems.
  
  
• Hazard scenarios were omitted, e.g. dust explosion hazards.

Omissions and deficiencies can be identified from QC reviews of PHA studies or by conducting PSM audits. However, QC reviewers must be technically qualified and competent for the review to be meaningful. Also, PSM audits may not identify omissions or deficiencies that exist in a PHA study because auditing involves the use of sampling and a PHA study may not have been included in the sample taken during an audit, Also, the auditors may not have the expertise required to identify PHA omissions and deficiencies.

Omissions and deficiencies found in PHA studies should be addressed by updating or revalidating the studies.

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