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What is HAZOP Study?

We keep learning thought out our life by many ways. We can better understand this learning process by some example. Let us say we are walking on a foot path. We stepped on banana skin, resulting in to fall. This is most crude way of learning, which is called as learning by own experience. In other case, a person walking ahead of you stepped on banana skin, resulting in to fall. This makes you cautious and you behave differently. This is called as learning from experience of other. If we look back at both the cases then we can understand that in both the cases some damage is already done.

Better way of learning is doing meditation or giving a deep thought or studying the process before doing any activity. HAZOP is something similar to this type of learning. HAZOP study is a systematic approach of studying complex process. HAZOP process uses simple guide words, to ensure that we do not miss out any risky activity.

Hazard and operability study or #HAZOP is a structured and systematic examination of a complex planned or existing process or operation. The purpose is to identify and evaluate problems that may represent risks to personnel or equipment.

HAZOP study is primarily done to review a process or operation in a systematic manner.  The purpose is to determine whether deviations from the design or operational intent can lead to undesirable consequences. This technique can be used for continuous or batch processes. The HAZOP technique was initially developed in the 1960s to analyze major chemical process systems but has since been extended to other areas, including mining operations and other types of process systems and other complex systems such as nuclear power plant operation and software development. It is also used as the basis for reviewing Batch processes and operating procedures.


What are basic requirements of HAZOP study?

  • Piping and instrumentation diagram (P&IDs) & process flow diagram (PFD).
  • Understanding of standardized guide-words
  • Cross functional HAZOP Team
  • Computers and projector screens for recording outcome of the meeting
Piping and instrumentation diagram (P&IDs) & process flow diagram (PFD).

Updated and finalized Piping & Instrument Diagram and Process Flow Diagram should be made available to the team.

Understanding of standardized guide-words

To identify deviations, the team systematically applies a set of Guide Words to each node in the process. These are general words such as Flow, Temperature, Pressure, and Composition. A standard set of Guide Words is given below.


Guide Word Meaning
NO OR NOT Complete negation of the design intent
MORE Quantitative increase
LESS Quantitative decrease
AS WELL AS Qualitative modification/increase
PART OF Qualitative modification/decrease
REVERSE Logical opposite of the design intent
OTHER THAN / INSTEAD Complete substitution
EARLY Relative to the clock time
LATE Relative to the clock time
BEFORE Relating to order or sequence
AFTER Relating to order or sequence
Cross functional expert HAZOP Team

A HAZOP study is a team effort. The team should be as small as possible consistent with required skills and experience. A larger team makes slower progress, which adds considerably to the costs. Each team member should have a definite role. Duplication of roles should be avoided. Let us look at a typical HAZOP team.

  1. Chairman – Is a person who, by his authority controls proceeding of HAZOP study. He is someone experienced and familiar with this type of process. He should be independent of the design team. He ensures that HAZOP discussion remains within scope of study.
  2. Project Manager
  3. Production Manager
  4. Chemical engineer or Chemist
  5. Maintenance Manager
  6. Electrical Engineer
  7. Instrument Engineer
  8. Quality Control Engineer
Computers and projector screens for recording outcome of the meeting

Computer with projector screen keeps HAZOP team on same track. This also helps in updating HAZOP proceeding on time.

Hazard and operability study

The HAZOP study is done to review the design to pick up design and engineering issues that may otherwise not have been found. The technique is based on breaking the overall complex design of the process into a number of simpler sections called ‘nodes’. Each node is then individually reviewed. It is carried out by HAZOP team during a series of meetings. The HAZOP technique is qualitative, and aims to stimulate the imagination of participants to identify potential hazards and operability problems. For each node in turn the HAZOP team uses a list of standardized guide-words and process parameters to identify potential Deviations from the design intent.

Our role in the HAZOP study

Guide management in formation of HAZOP team

Carry-out HAZOP training for the participants

Facilitate the team to carry out systematic examination sessions

Use of standard guide words for simulation

Guide the discussion to obtain meaningful results

Record the discussions and submit the report to the management