Unlike checklists where very specific, and limited, questions are asked HAZOPs creates questions customized to the process under study. It does this by a systematic examination of the safe process "intent" using a standard list of "guidewords". Guidewords are modifiers used to create deviations from the stated intent. Words such as "No", "More", and "As Well As" are added to the process parameters such as Flow, Temperature and Level to create a deviation. An example is: High Flow Amount (More Flow) leads to a tank overfill and overflow, a deviation from intent. Once a deviation has been identified, the examination team determines the direct causes and failures required to initiate the upset. If the deviation could result in a process hazard, then the team reviews the existing, or intended, safeguards to prevent or mitigate the hazard. The team may recommend actions to improve risk management, such as equipment or procedure modifications.

The HAZOP technique is very versatile, and can be applied to both continuous and batch processing. Guideword lists have been created to support the use of HAZOP as a technique for analyzing operating procedures, to ensure safe operation. The method is often time consuming, and therefore best reserved for new, highly hazardous processes, or sections of the process where experience is lacking.

If you're an OSHA PSM or EPA RMP site, you need to complete PHA studies of new processes. In addition, all chemical processing facilities should use PHA as the cornerstone of their process safety management program. Chilworth Technology can help. Chilworth Technology has qualified, and experienced Process Safety Engineers capable of leading your PHA effort or providing low cost in-house training in PHA methods, including HAZOP.

Hazard & Operability Study is undertaken to review the design and operation of the hazardous facility. In this study, a team comprising of Plant personnel and Chilworth experts is constituted. This team identifies all causes of deviation from usual safe operations that can lead to any safety hazard or operability issue. The hazop team explores all the possible causes of the problem and its consequences. This is done after application of relevant guide words, considering process parameters and extensive brainstorming sessions within the team. After this, 'actions to be taken' are decided upon by the team. All the discussion and decisions are appropriately recorded and comprehensive hazop study report is prepared.