Process and
guidewords for
procedural HAZOPs
When organisations develop new processes or
procedures or revise existing ones, there is great
value in stress-testing the proposed new
arrangements to ensure they will work as intended,
and will not generate unintended adverse
consequences. Procedural HAZOPs provide one way
of doing this. This technical note outlines the process
we use for procedural HAZOPs and the guidewords
we recommend for such studies.

Contents
1 Background 3
2 Stress testing of procedures 3
3 Conducting a procedural HAZOP 4
4 Guidewords for a procedural HAZOP 6
5 Contact 8

Tables
T a b l e 1 : G u i d e w o r d s f o r a p r o c e d u r a l H A Z O P 6

1 Background
T h e hazard and operability (HAZOP) process has been applied traditionally to
chemical, petrochemical and related processing plants and systems. There it is
used to investigate the causes, controls and consequences of events or
circumstances that might cause the system to function outside its designed
‘normal’ and ‘safe’ operating states.
Despite its origins in the chemical and petrochemical sector, the HAZOP process
works very well for all systems and processes, both technical and non-technical.
It is now applied in diverse range of applications such as software development,
procedure writing, contract development and organisational change.
The HAZOP process examines each of the critical properties of a system in turn.
It stresses each one by discussing what could cause that property to move
outside the envelope that is regarded as safe. This facilitates the specification
and design of controls that ensure the system never becomes ‘unsafe’. Unsafe
in this context means unacceptable in terms of performance when compared
with the organisation’s objectives.
2 Stress testing a procedure
Stress testing is achieved by asking questions based on a set of guidewords.
Each guideword is a combination of words that describe a critical property or
parameter of the system and how it might deviate from normal or expected
behaviour.
• Key parameters are commonly related to system properties like ‘action’,
‘time’ and so on
• Deviations are commonly expressed in terms of words like ‘no or not’,
‘more’, ‘less’, ‘as well as’, ‘part of’, ‘reverse’ and ‘other than’
• For example, in a classical HAZOP of a fluid flow system, where flow is a key
parameter, combining deviations with the parameter ‘flow’ generates
guidewords like ‘no flow’, ‘more flow’, ‘less flow’, ‘reverse flow’ and so on
• In a HAZOP of a procedure, where action is a key parameter, combining
deviations with the parameter ‘action’ generates guidewords like ‘no
action’, ‘more action’, ‘less action’, ‘wrong action’ and so on.
Most organisations rely on procedures to ensure their activities are undertaken
consistently and to acceptable standards. Despite the significance of
procedures in terms of business performance, few organisations undertake
formal or systematic risk assessments before they are introduced, or monitor
 Many organisations have
felt the adverse effects of procedures that have been poorly designed or poorly
implemented.
Risk management is concerned with adding value and providing the means for
managers to make confident and soundly based decisions. A HAZOP study is a
form of risk assessment that can be applied to procedures, whether they are
being designed, being implemented or already in place and working.
A HAZOP study provides a check on a procedure’s resilience by testing how it
responds to stresses or excursions outside normal conditions, as represented by
the guidewords. This can assist in:
• Identifying the possible consequences of a new procedure or a procedural
change
• Indicating where the design of a procedure might be improved, either to
prevent a failure or under-performance, or to capture and lock in better
performance than expected
• Developing additional actions to ensure that the change is successful, in the
sense of achieving the organisation’s objectives effectively and efficiently.
3 Conducting a procedural HAZOP
Preparation
Like any form of risk assessment, the context for the procedure should be
established in terms of:
• Its purpose and how it is intended to contribute to the organisation’s
overall objectives
• Its scope of application
• The stakeholders associated with the procedure and their objectives
• The external and internal factors that might influence the procedure and
the way it works.
Establishing the context takes place before the risk assessment, and it only
involves a few people for a few hours. The outcomes should be recorded in a
briefing note for the HAZOP workshop participants.
Before the workshop, the procedure should be split into ‘key elements’ to
facilitate a comprehensive examination. Often the most appropriate key
elements are the steps in the procedure. The elements may be extended to
include the application of the procedure in different circumstances, supporting
, phases of the proposed implementation or other
aspects such as publicity, morale or supervision.
Participants
A HAZOP workshop requires a trained facilitator and a recorder.
The other participants in a workshop should be selected from:
• Those who typically will have to follow or operate the procedure
• Those who must review or monitor the operation of the procedure,
including managers and supervisors and, in some circumstances, members
of the internal audit team
• Specialists from such areas as safety, legal or engineering who can offer a
different perspective.
Conduct
Typically, a HAZOP workshop takes from two to four hours, depending on the
complexity of the procedure.
The workshop should start with a quick review and update to the statements in
the briefing note. The base guideword set shown in Table 1 below is then used
to prompt risk identification. The facilitator may choose to add guidewords that
are relevant for the organisation or the specific application.
The facilitator should help the team work through the guideword list and apply
each guideword to each of the key elements in turn. Some guidewords may be
irrelevant for some key elements and they can be omitted. In each case, the
team should discuss:
• What might cause the circumstances described by the guideword
• The nature and extent of the consequences if that situation occurred
• The controls in place to change the likelihood of that situation arising or the
consequences if it did arise
• Any further controls that would be required to treat the risk
• The priority for risk treatment action, using the organisation’s normal risk
rating process.

Outcomes
T h e o u t c o m e o f t h e workshop should be a list of amendments to the
procedure, together with any ancillary actions to reduce the risk and ensure the
organisation is successful and achieves its objectives.
The amendments and actions might involve:
• The re-wording of instructions for steps in the procedure
• The re-ordering of steps or instructions
• The addition of warning or ‘watch-out’ notes to the procedure
• A revised assessment of factors that could affect the performance of those
who must follow the procedure and that might lead to changes in training,
workplace design, skills assessment or supervision.
More radical solutions might involve greater automation rather than manual
processing, or even stopping the process or the procedural change if it were
judged that the risk remained too high.
All proposed risk treatment actions should be costed, and the costs should be
considered in the overall cost benefit analysis that is used to justify the
procedure or the procedural change. Where the costs and benefits are not
tangible or cannot be expressed easily in a single metric, such as dollars, then
qualitative cost benefit analysis should be applied.
4 Guidewords for a procedural
HAZOP
Table 1 lists typical guidewords for a procedural HAZOP study. Each guideword
is accompanied by topics that might be considered and discussed in a HAZOP
workshop when the guideword is applied to a key element or step in the
procedure.
Table 1: Typical guidewords for a procedural HAZOP
Guide word Topics for discussion
Purpose Is the step needed? Is the intent of this step clear? Can
this step be mis-applied?
No action Step is missed or omitted; intended operation did not
occur (hardware failure); action impossible; system not
ready......................................................................................................................................................................................