HAZOP Procedure

A HAZOP procedure is an examination of an existing or planned operation (work) procedure to identify hazards and causes for operational problems, quality problems, and delays.

  • Can be applied to all sequences of operations
  • Focus on both human errors and failures of technical systems
  • Best suited for detailed assessments, but can also be used for coarse preliminary assessments
  • Flexible approach with respect to use of guide-words

HAZOP Procedure

Breakdown of operation (work) procedure to suitable steps

  • Define intention of each step
  • Establish boundary conditions else as conventional Process HAZOP
  • Apply guide-words to intention and boundary conditions for each step.

HAZOP Guidewords:

Guideword Meaning
No (not, none) None of the design intent is achieved
More (more of, higher) Quantitative increase in a parameter
Less (lessof, lower) Quantitative decrease in a parameter
As well as (more than) An additional activity occurs
Part of Only some of the design intention is achieved
Reverse Logical opposite of the design intention occurs
Other than (other) Complete substitution – another activity takes place


Alternative Guidewords:

Guideword Meaning
Unclear Procedure written in confusing and ambiguous fashion
Step in wrong place Procedure will lead to actions out of correct sequence or recovery failure
Wrong action Procedure action specified is incorrect
Incorrect information Information being checked prior to action is incorrectly specified
Step omitted Missing step, or steps too large, requiring too much of the operator
Step unsuccessful Step likely to be unsuccessful due to demands on operator
Interference effects from others Procedure-following performance likely to be affected by other personnel carrying out simultaneous tasks (usually when co-located)


Alternative Guidewords/Deviation:

Guideword Meaning
Time Too early, too late
Sequence Wrong sequence, omissions, wrong action
Procedure Not available, not applicable, not followed
Measurement Instrument failure, observation error
Organization Unclear responsibilities, not fitted for purpos
Communication Failed equipment, insufficient/incorrect information
Personnel Lack of competence, too few, too many
Position Wrong position, movement exceeding tolerences
Power Complete loss, partly lost
Weather Above limitations – causing delayed operation


HAZOP Reporting:

A typical HAZOP report consists of:


  1. Introduction
  2. System definition and delimitation
  3. Documents (on which the analysis is based)
  4. Methodology
  5. Team members
  6. HAZOP results

– Reporting principles

– Classification of recordings

– Main results

HAZOP Review:

Review meetings should be arranged to monitor completion of agreed actions that have been recorded. The review meeting should involve the whole HAZOP team. A summary of actions should be noted and classified as:

  • Action is complete
  • Action is in progress
  • Action is incomplete, awaiting further information

HAZOP Results:

What results to expect?

  • Improvement of system or operations
  • Reduced risk and better contingency
  • More efficient operations
  • Improvement of procedures
  • Logical order
  • Completeness
  • General awareness among involved parties
  • Team building

The purpose of this is to investigate how the system or plant deviates from the design intent and create risks for personnel and equipment and operability problems. HAZOP studies have been used with great success within chemical and the petroleum industry to obtain safer, more efficient and more reliable plants.


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