14, Number 2
A Gossman Consulting, Inc.
- Before You Start
In 1998 we published a GCI Tech
that summarized the HAZOP process. Recently I had the
to teach a class on performing HAZOPs to a group of safety
professionals in Shanghai, China. As a result of that
further information on the process of performing HAZOPs will be
presented in a new series of GCI Tech Notes. This is the second in that
Presuming that you have examined the pros and cons of performing a
HAZOP vs. another type of hazard identification process the next step
is to gather information that will be needed prior to commencing the
actual HAZOP process. An accurate and complete design of the process
that will be examined is critical to the success of the HAZOP process.
Doing a thorough job of gathering this information in advance of
commencing the HAZOP itself can save time and money that would be
wasted if it becomes necessary to repeatedly pause or even redo
portions of the HAZOP as members of the team realize the information
gathered in advance is incomplete or out dated.
boundaries of the object or system of the study and the interfaces at
the borders needs to be established well in advance in order to
facilitate the gathering of information needed for the HAZOP. This
process should result in a clear statement of the scope and objectives
of the HAZOP study that will be performed.
In general, HAZOP studies seek to identify all hazards and operating
problems regardless of type or consequences. Focusing a HAZOP study
strictly on identifying hazards can enable the study to be completed in
shorter time and with less effort but much of the benefits that make a
HAZOP uniquely cost effective may be lost. The following factors should
be considered when defining objectives of the study:
- The purpose for which the results of the study will be used.
- The phase of the life cycle at which the study is to be
- Persons or property that may be at risk, for example
employees, the general public, the environment, the system.
- Operability problems, including effects on product quality.
- The standards required of the system, both in terms of
safety and operational performance.
Basic Information Needs
As a basis for the HAZOP study the following types of information
should be available depending on the specific nature of the process
that will be examined:
- Process flow diagrams.
- Piping and instrumentation diagrams (P&IDs).
- Layout drawings.
- Material safety data sheets for any hazardous materials
used or produced by the process.
- Provisional (our current for an existing operation)
operating instructions - often referred to as SOPs (Standard Operating
- Heat and material balances.
- Equipment data sheets and specifications.
- Start-up and emergency shut-down procedures.
All design documentation should be clearly
and uniquely identified, approved and dated. The design descriptions
for programmable electronic data systems may include
object-oriented design diagrams,
state transition diagrams,
and/or logic diagrams. Remember that even if the process that is being
examined is not a software or programmable logic system in and of
itself, it likely contains some and perhaps many of these systems as
part of the overall control and monitoring of the operation. As such,
including these systems is likely to be a critical part of the overall
The following additional information can also be helpful if obtained in
advance of the start of the HAZOP review.
Next Up - Management of
the HAZOP Process and Team
environmental conditions in which the system will operate.
- Operating and maintenance personnel qualifications, skills
- Operational and maintenance knowledge and known
hazards with similar systems.