What is HAZOP?
A Hazard and Operability (HAZOP) study is a structured and systematic examination of a planned or existing process or operation in order to identify and evaluate problems that may represent risks to personnel or equipment, or prevent efficient operation.
The HAZOP technique was initially developed to analyse chemical process systems, but has later been extended to other types of systems and also to complex operations and to software systems.
A HAZOP is a qualitative technique based on guide-words and is carried out by a multi-disciplinary team (HAZOP team) during aset of meetings.
History Of HAZOP
HAZOP STUDY is a legal requirement as per the rules 10 to 13 under Manufacture, storage and import of Hazardous chemicals rules, 2000 and environment (protection) Act, 1986. It is obligatory of the occupier to carry out a "HAZOP Study", as required under item no. (II) (2) of the format for application of the Site Appraisal Committee and as per the Schedule 1 of the Factories Act under Section 2(CB) - Item No. 11 of the Schedule.
The basis for HAZOP was laid by ICI in 1963 and was based on so-called “critical examination” techniques First guide: “A Guide to Hazard and Operability Studies”, ICI and Chemical Industries Associations Ltd. 1977.
When To Perform a HAZOP?
The HAZOP study should preferably be carried out as early in the design phase as possible - to have influence on the design. On the other hand; to carry out a HAZOP we need a rather complete design. As a compromise, the HAZOP is usually carried out as a final check when the detailed design has been completed.
A HAZOP study may also be conducted on an existing facility to identify modifications that should be implemented to reduce risk and operability problems.
HAZOP studies may also be used more extensively, including:
At the initial concept stage when design drawings are available
When the final piping and instrumentation diagrams (P&ID) are available
During construction and installation to ensure that recommendations are implemented
During operation to ensure that plant emergency and operating procedures are regularly reviewed and updated as                   required
Types Of HAZOP
Process HAZOP : The HAZOP technique was originally developed to assess plants and process systems.
Human HAZOP : A “family” of specialized HAZOPs. More focused on Human errors than technical failures.
Procedure HAZOP : Review of procedures or operational sequences Sometimes denoted SAFOP - Safe Operation Study.
Software HAZOP : Identification of possible errors in the development of software.
HAZOP is a systematic, reasonably comprehensive and flexible.
It is suitable mainly for team use whereby it is possible to incorporate the general experience available.
It gives good identification of cause and excellent identification of critical deviations.
The use of keywords is effective and the whole group is able to participate.
HAZOP is an excellent well-proven method for studying large plant in a specific manner.
HAZOP identifies virtually all significant deviations on the plant, all major accidents should be identified but not necessarily their causes.
Accuracy of drawings and data used as a basis for the study
Experience and skills of the HAZOP team leader
Technical skills and insights of the team
Ability of the team to use the HAZOP approach as an aid to identify deviations, causes, and consequences
Ability of the team to maintain a sense of proportion, especially when assessing the severity of the potential consequences.