What is the Hazard and Operability Study?

The Hazard and Operability Study (HAZOP) is a systematic investigation of a present or planned process or operation. The HAZOP study is aimed at identifying and evaluating any problems within a plant or work environment that could pose a risk to the employees and/or equipment.

The HAZOP also looks at processes that might impede the efficient running of the facility. Originally, hazard and operability studies focused on chemical and mining operations. The study was extended to include nuclear power plants.

How Does it Work?

The intent of the HAZOP study is to review the plant. This is done by the HAZOP team in a series of meetings. The team methodically "brainstorms" the plant design. This brainstorming stimulates creativity and generates ideas through team member interaction.

The process requires the full participation of each team member. During the study, team members must resist criticizing suggestions of other team members. All ideas are openly received and considered. The team’s focuses is on specific points of the design. These are explored one by one. What the team is looking at is deviations in the process parameters.

Guide words are used to guarantee that the design is examined from every possible angle. The team identifies a fairly large number of deviations. Next, each is considered as a potential cause or effect of operations or hazards.

HAZOP effectiveness is largely determined by:

  • The parameters and exact description of the study
  • The skills and experience of the team members
  • The team’s ability to work well together
  • Meaningful questions asked by the HAZOP team
  • Completeness and accuracy of the studyThe ability of the team to use the outlined approach
  • The ability of the team to identify and concentrate on serious hazards and not get sidetracked by sheer breadth of the study

The HAZOP study is carried out by experienced team members with multi-disciplinary skills. Usually the team includes four or five members. During a set of meetings the HAZOP team conducts a qualitative assessment aimed at drawing attention to problems and hazards in the operation.

Efforts are made to keep the team as small as possible and still include those with relevant skills and experience related to the processes and operations being studied. Large studies may include as many as twenty team members and several team meetings. The makeup of the team may change as different areas and aspects of the organization are studied.

Guide words help frame the parameters of the HAZOP team study. The guide words provided represent a standard set. Different sets of guide words are based on the type of unit operation being studied. Typical guide words include: AS WELL AS, PART OF, and OTHER THAN. Though guide words are meant to be helpful, sometimes they can be difficult to apply. Guide words are combined with process parameters like: flow, temperature, level, viscosity, and pH level.

HAZOP looks for deviations from the norm. Once deviations are identified, causes for those deviations are explored. These may involve materials, procedures or human error.

Why is HAZOP Important for Safety Professionals?

A Hazard and Operability study is one of the techniques used by safety professionals to explore the system and ensure that hazardous and/or inefficient procedures are identified and corrected. HAZOP studies provide analysis and details about hazards or errors in a system design.

HAZOP studies highlight potential hazards and problems in the operation so that safety professionals can then decide upon the most effective means of remedying the problem. HAZOP studies may help avoid problems and, therefore, save lives and/or business expenses.

Positive Aspects of a HAZOP Study

  • An efficient, knowledgeable HAZOP team may save the company more than the expense of the study in efficiency changes
  • HAZOP studies identify hazards and can thus save lives and decrease employee injuries
  • HAZOP teams ensure the study is multi-disciplinary

Disadvantages of a HAZOP Study

  • HAZOP studies are very time consuming, and can often end up costing a lot in expenses
  • HAZOP teams focus on individual areas or single events rather than a combination
  • A competent facilitator and a knowledgeable, experienced HAZOP team are crucial
  • A HAZOP study focuses on specific guide words. Thus, some hazards or operational problems may be overlooked

Hazard and Operability Study Tips

HAZOP studies can fall into several pitfalls, and these have given HAZOP teams a bad reputation.

HAZOP studies can be very long, tedious and lacking in focus. The following tips may help to make HAZOP studies more efficient and effective.

  1. Plan the HAZOP meetings well in advance.
  2. Select a HAZOP team that has the necessary skills. Do they all understand the design, operation or procedure that is being studied?
  3. Know what the HAZOP study’s focus is: Are you reviewing a concept, procedure, operation, or design?
  4. What are the parameters of the study? Is the team clear on this?
  5. Well before the study, an information package needs to be prepared. This resource packet should contain support information for the team.
  6. Before the HAZOP study the resource information must be scrutinized for accuracy and validity.
  7. The team should decide how computer software might assist in their study.
  8. The chairperson of the HAZOP team should address the group outlining the scope of the study and how the HAZOP team will function. For several team members, this may be their first HAZOP study.
  9. The designer should present an overview of the scope of the study.
  10. The facilitator should ensure that each team member makes contributions related to his area of expertise and participates in the study.
  11. The HAZOP team should avoid preconceived ideas and expectations because “this is usually the way it works” or “it never happens this way.”
  12. The HAZOP team should allocate its time according to the priority of the risk or operational issue.
  13. The HAZOP study plan should have a comfortable amount of time so that the team has breaks to refocus.
  14. The HAZOP study should allow sufficient time so it finishes on time or early. Tight time lines risk hurried studies which make mistakes.
  15. HAZOP team meetings should have detailed minutes so recommendations can evolve from them.
  16. HAZOP study follow-up should ideally include recommendations and potential solutions to identified problems.