GUIDELINES FOR CONDUCTING HAZOP STUDIES

TABLE OF CONTENTS
1.0 Review of HAZOP Technique
1.1 The Basic Concept……………………………………………. 2
1.2 Role of HAZOPs in Risk Assessment………………………. 4
1.3 Background of HAZOP Technique………………………….. 7
1.4 Guide Word HAZOP Technique…………………………….. 11
1.5 An Example…………………………………………….. 18
2.0 Procedure for Conducting a HAZOP Study
2.1 Definition of Objectives and Scope…………………………. 23
2.2 Team Composition……………………………………………. 27
2.3 Estimating Time Requirements……………………………… 29
2.4 Preparative Work……………………………………………… 32
2.5 Study in Practice………………………………………………. 36
2.6 Risk Ranking……………………………………….………….. 42
2.7 Recording and Reporting………………………………………….. 50
3.0 Programmin g HAZOP Studies
3.1 Early Checking for Major Hazards……………………………….. 52
3.2 Studies at Design Freeze Stage…………………………………. 55
3.3 Studies at Pre-Start Up……………………………………………. 57
3.4 Studies on Existing Plants………………………………………… 58
3.5 Studies Prior to Plant Modifications………………..……………. 59
3.6 Studies Prior to T & I……………………………………..……….. 61
3.7 Studies on Research Facilities/Laboratories…………………… 63

4.0 HAZOP Studies 
4.1 Initiation of HAZOP Studies……………………. 65
4.2 Training ……………………………………………………………… 67
5.0 Examples of HAZOP Studies
5.1 Application to a Continuous Plant………………………………… 71
5.2 Application to a Batch Plant………………………………………. 75
5.3 Application to a Proprietary Item of Equipment…………………. 78
5.4 Application to Operating Procedures…………………………….. 83

In recent years, the use of the HAZOP (Hazard and Operability) study technique has
increased enormously, particularly in the USA and Europe, and is indeed mandatory in some companies. The method is now well established as a means of identifying potential plant design hazards and operability problems

The HAZOP technique is a highly disciplined procedure and attempts to identify how a
process may deviate from the design intent. The emphasis in the HAZOP study is on
identifying potential problems, not necessarily solving them. If, however, a solution is obvious
during the study, it is recorded or incorporated immediately while the study is in progress. The
“guide word” HAZOP technique is the most widely known and is one of the hazard
identification techniques used by Saudi Aramco.
In a HAZOP study, a team of individuals systematically “brainstorms” the process under
review in a series of meetings using a set of guide words to structure the review. The team is
composed of individuals representing a variety of departments/specialties. This multidisciplinary team concept allows the various viewpoints of the team members to stimulate the
thinking of the other team members and results in creative thinking. Consequently, a more
thorough review is achieved than would occur if members of the team individually reviewed
the same process.
A typical HAZOP study team may consist of the representatives from the following disciplines:
· Inspection
· Instrumentation/Electrical
· Loss Prevention/Fire Prevention
· Maintenance
· Operations
· Operations/Process Engineering
· Other Specialists as required
The HAZOP study is conducted by systematically applying guide words with appropriate
process parameters to the various lines and vessels in the plant (identifying deviations from
the design intent of normal process conditions).
The HAZOP technique is based upon the following fundamental principles:
· Obtain a full description of the process, including the intended design
conditions.
· Systematically examine every part of the process to find out how
deviations from those designed or specified can occur.
· Decide whether these deviations can give rise to hazards and/or
operability problems.
These principles can be applied to operating process plants or to plants in various stages of
design.