Hazard and Operability Studies – HAZOP
The HAZOP methodology is in essence an adaptation of the FMEA for applications within
the process industry considering flows in pipelines and process units. However, the principles
of the HAZOP may easily be applied to many other application areas.
The HAZOP takes basis in assessing for each item of the considered system the possible
problems or deviations, which could be problematic for the function of the system. The results
of the HAZOP are summarised in tables containing a list for each considered item giving:
Descriptions of deviation
Causes of deviations
Consequences of deviations
Actions for reducing the probability and consequences of deviations.
In filling out the lists so-called standardised guidewords are provided including, NO/NOT,
MORE OF, LESS OF, OTHER THAN, AS WELL AS, PART OF and REVERSE. It is clear
that these words have origin in the process industry, but abstractly interpreted they may be
adapted for other application areas also.
Risk Screening Sessions - HAZID
Risk screening or HAZID sessions are widely applied especially in the offshore engineering
area where e.g. production facilities are considered comprising a very large number of
functions, sub-systems and components.
Risk screenings are performed on a predominantly qualitative basis with the main purpose of
getting an initial overview of the important characteristics of the considered system. A central
aim is to identify the constituents of the system, i.e. the sub-systems and components, which
clearly need no further quantitative assessments, and thereby to limit and focus further
assessments on the important issues of risk.
The sessions are performed in the form of meetings with the participation of all categories of
personnel involved at some stage and/or some function of the considered engineering system.
If a risk analysis of a bridge structure is considered relevant categories of personnel are e.g.
design engineers, inspection and maintenance personnel, materials experts, geotechnical
engineers, persons from the owner and/or operating organisation and finally persons with
experience in risk and reliability analysis.
Prior to the meeting the considered system is identified with its sub-systems and components
and described in regard to functionality and boundaries and it is clearly specified what types
of consequences are the subject of the meeting (personnel, environment and economical).
Furthermore it is important that relevant incident databases are searched for relevant
information in regard to failures and near failures of similar systems, sub-systems and
components in the past. This information is distributed to the participants prior to the meeting
as a basis for preparation.