HAZARD RISK ASSESSMENT REPORTS
Major Hazard Installation Regulations have been in South African
legislation since 2001 and still today many employers, their safety and
risk managers have limited or incorrect knowledge in what is an Major
Hazardous Installation(MHI) .
The Occupational Health and Safety Act defines a Major Hazard
Installation as (a) where more than the prescribed quantity of a
substance is kept or maybe kept (The listed substances are provided in
General Machinery Regulations Schedule A) and (b) where the substance
is processed, produced, used ,handled or stored which has the potential
to cause a major incident.
Most forget (b) .This could be a chemical stored
for example sulphur
.If this ignites the toxic air contaminants released is Sulphur dioxide
and sulphur trioxide and this would cause an offsite major incident.
This scenario is possible for many chemicals some in reasonably small
quantities .The South Africa legislation and those in a number of other
countries requires a risk assessment to determine the potential risk,
consequence and also to assess the suitability of the existing
emergency plan. This risk assessment is a QRA
Regardless of the type of hazard being evaluated, quantitative risk
assessment always includes the same general steps:
• Hazard Identification
• Consequence Assessment
• Frequency Assessment
• Risk Characterisation
Depending on the type (area) of risk, the second and third steps may be
described slightly differently (for example in a chemical exposure QRA,
the steps are called toxicity assessment and exposure assessment), but
they still deal with consequence and frequency of occurrence.
Hazard identification always comes first and risk characterisation
always occurs last in the process, but consequence and frequency are
typically evaluated simultaneously.
A graphical representation of the
QRA process is presented in the following figure.
The Report should include
This section should define the purpose and identify the scope,
objectives and the basis of the study clearly need to be identified.
The introduction leads into the main body of the report. It should also
incude a clear description of the site and location
2. METHODOLOGY and DATA SOURCES
A large number of methods are available and are used. A
description of the details how the report was compiled and a
description of the methodology used for the analysis is important.
Proposed new legislation and SANS Code of Practice on the Risk
Assessment in South Africa will provide clearer guidance .Where changes
have been made to the approach to Hazard Identification, Consequence
Assessment, Failure Frequency and Probability Estimation, and Risk
Analysis taken must be specified.
Sources of data should be clearly identified so that the analysis is
reproducible from the base data if necessary. All assumptions,
including operating philosophy and any modelling simplifications should
be thoroughly discussed.
2.1 HAZARD IDENTIFICATION
This is a critical aspect of the MHI Risk Assessment. All chemicals,
processes and activities should be identified and their potential
controls and potential risk determined. Sometimes risk assessors ignore
simple issues which could present a significant risk. For example dust
on floors and around equipment or on rafters. This dust could be
flammable and explosive .This section should present the hazards that
were identified as a part of the process and the means by which the
task was completed (HAZID, HAZOP, etc.). The personnel that
participated in hazard identification should be noted. In South African
terms this must be the SANAS accredited MHI Risk Assessor.
2.2. CONSEQUENCE ASSESSMENT
The results of the consequence assessment must be presented a. The
worst case or cases must be provided and these should clearly
illustrate the potential effects and areas of concern. Alternative
scenario(s) must also be determined and modelled. These should also
identify the risks and areas of concern or impact. The means by which
losses are defined should be detailed
2.3 FREQUENCY ASSESSMENT
For a risk to occur a loss of containment or control has to occur. MHI
require the actual or potential failure rate to be determined or
calculated. Currently there are many sources of the data. These include
UK HSE failure rates, Bevi and many others. New SA legislation will
provide guidance. The risk assessor should provide details of the
source(s) and also explain the logic behind different failure
mechanisms, details of the logic behind the event trees and fault trees
analyses if used, etc.
2.4 RISK CHARACTERISATION
The primary purpose of the MHI Risk Assessment is to characterised the
risk. This section should provide the specific risk statistics that
have been derived to present, rank and evaluate the hazards that were
evaluated. It should also summarise what options have been evaluated
and the criteria by which the statistics will be ranked. The
characterisation of risk is the main purpose of the report, so the
reader should be taken back to the original objectives and indicate how
they have been fulfilled.
All risk assessments including MHI Risk Assessments must have
recommendations. If recommendations are made, they should be confined
strictly to the scope of the work. Additional findings and
recommendations that are arrived at during the course of the exercise
should be addressed separately from the MHI Risk Assessment Report.
Provide a list of all references used for the MHI Risk Assessment so
that results and conclusions are fully traceable and auditable.
SA MHI legislation requires Appendices. This includes Department of
Labour Accreditation Certificate, SANAS accreditation and an Executive
Report Summary and other Appendices. These other Appendices should
contain relevant information or data that might make the report easier
to understand In some instances it can contained detailed information
which may not be for all readers and is not appropriate in the main
body of the report. SA legislation also requires the site Emergency
plan to be provide and to be evaluated by the Risk Assessor. All HI
Risk Assessment Reports will be read by a wide variety of persons .It
can be beneficial to place the detailed technical analysis for outflow
modelling, frequency assessment, consequence modelling and fatality
assessment in the Appendices, such that the main body of the report
remains readable from a non-technical reader.
POLICY II ANTI-SPAM II AUP
II SECTION 51