Study 2: Front-End Engineering Design and Project Definition

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Process Safety Guide:
GBHE-PSG-HST-030
Study 2: Front-End Engineering
Design and Project Definition
Process Information Disclaimer
Information contained in this publication or as otherwise supplied to Users is
believed to be accurate and correct at time of going to press, and is given in
good faith, but it is for the User to satisfy itself of the suitability of the information
for its own particular purpose. GBHE gives no warranty as to the fitness of this
information for any particular purpose and any implied warranty or condition
(statutory or otherwise) is excluded except to the extent that exclusion is
prevented by law. GBHE accepts no liability resulting from reliance on this
information. Freedom under Patent, Copyright and Designs cannot be assumed.

Process Safety Guide: Study 2: Front-end Engineering Design
And Project Definition
CONTENTS
2.0 PURPOSE
2.0.1 Team
2.0.2 Timing
2.0.3 Documentation
HAZARD STUDY 2: APPLICATION
2.1 Study of Process and Non-Process Activities
2.2 Study of Programmable Electronic Systems (PES)
2.3 Risk Assessment
2.4 Defining the Basis for Safe Operation
2.5 Review of Hazard Study 2
APPENDICES
Appendix A Hazard Study 2 Method
A.1 Significant Hazards Flowsheet
A.2 Event Guide Diagram
A.3 Consequence Guide Diagram
A.4 Typical Measures to Reduce Consequences

Appendix B Programmable Electronic Systems (PES) Guide Diagram
Appendix C Risk Assessment
C.1 Risk Assessment Procedure
C.2 Risk Matrix
C.3 Risk Matrix Guidance for Consequence Categories – Safety and Health
Incidents
C.4 Risk Matrix Guidance for Consequence Categories – Environmental
Incidents
Appendix D Key Hazards and Control Measures
Appendix E Content of Hazard Study 2 Report Package.

2.0 PURPOSE
The depth of hazard identification and risk assessment and the methodology
used should be appropriate to the risk to safety, health, the environment or the
Business.
This document covers Hazard Study 2, which typically covers hazard
identification and risk assessment, operability and control features that should be
built into the detailed design, and any special environmental features to be
covered.
• In new plants or installations or in modifications, identification of the
hazards provides the opportunity for redesign to eliminate or significantly
reduce the risk. Where the risk cannot be reduced to tolerable levels by
practicable redesign, protective measures may need to be incorporated to
meet the relevant criteria. The study should help produce most of the
majority of the information and assessments needed to meet the
requirements of the regulatory authorities on safety, health and
environmental protection.
• When applied to existing plants or installations, Study 2 has the similar
objectives of identifying significant hazards, their possible causes and
protective measures to meet relevant criteria. The objective of the study is
usually to identify aspects of existing hardware and operations that do not
comply with modern standards or criteria. Critical features of the
hardware, procedures and instructions will be identified.
This document should be used in conjunction with a process safety publication
such as ’HAZOP: Guide to best practice’ (available from IChemE) or ‘Guidelines
for Hazard Evaluation Procedures’ (available from CCPS).
2.0.1 Team
The team composition should be agreed between the Hazard Study Leader and
the Project Manager. Assistance in selecting team size and membership can be
found in the 'HAZOP: Guide to best practice' book.
The same team composition should be suitable for the study of Programmable
Electronic Systems (PES) (see 2.2). Unless adequate expertise is available on
site it will be necessary to include the supplier’s representative and possibly a
process control expert.

2.0.2 Timing
The study of process and non-process activities can be started as soon as a
description of the process and the process flowsheet or flow diagram, or the
building layout and services distribution, are available. For Study 2 of the process
it may be helpful to have a draft pressure relief philosophy.
For the study of Programmable Electronic Systems (e.g. PLC or DCS), the
Hazard Study 2 meetings should be complete to the extent that all significant
hazards have been identified on all parts of the project where the PES system is
used for control or as part of an instrumented protective system. The project
should have reached the stage where the Project Definition is complete, the User
Requirement Specification (URS) is complete and the PES supplier has been
chosen and has provided an outline design of the PES system.
Completion of Hazard Study 2 helps in the production of a sanction estimate for
the project.

2.0.3 Documentation
The study is generally recorded on the worksheet entitled Hazard Study 2
(worksheet k).
A contents sheet for this study and associated documentation is available,
entitled Hazard Study 2 Report (worksheet m).

HAZARD STUDY 2: APPLICATION
The following sections 2.1 to 2.5 describe how to conduct Hazard Study 2.

2.1 STUDY OF PROCESS AND NON-PROCESS ACTIVITIES
The study team works systematically through the process
flowsheets, identifying significant hazards associated with
each stage of the process. The most significant hazardous
events are often loss of containment ’LOC’.
For each new diagram or system, a brief explanation of the
process and proposed operation is required, to ensure that
each member of the team has an adequate understanding
for their active, effective participation in the study.
Where there are several unit operations, the team can
study them as a small number of separate process related
’blocks’. The Hazard Study Leader will provide guidance in choosing a suitable
division into these ’blocks’.
A diagram of the method used is given in the Significant Hazards Flowsheet (see
appendix A.1). The study proceeds, considering one block at a time, using the
guidewords in the Event Guide Diagrams (see appendix A.2).
The study should be recorded on the Hazard Study 2 worksheet (worksheet k).
Where quantification of hazards is required, expert guidance on methodology is
suggested.
Consideration should also be given to non-process activities that can give rise to
potential safety, health or environmental hazards. The GBHE Engineering
Procedures (EPs) define requirements for identification of non-process hazards
and management systems to control those hazards.
The following drawings and documents may be helpful and these should be
included in section 2.2 of the Hazard Study 2 Report (worksheet m).
(a) Site plans, floor plans, photographs.
(b) Service distribution drawings (in lieu of flowsheets or line diagrams).
(c) Pressure regimes.
(d) Material Data Sheets.

2.2 STUDY OF PROGRAMMABLE ELECTRONIC SYSTEMS
(PES)
The Hazard Study 2 will have produced a list of identified
hazardous events. If these are significant a study of the PES
should be considered. The intention of the study of a PES is to
look at potential failures of the PES and to determine what role
the PES plays in each of these identified events where
appropriate.
If any aspects of the PES are involved in protecting against an
identified hazardous event that could cause serious harm to
people or the environment, then an analysis of the protective
role of the PES may be needed. Specialist advice should be
sought.
The study should consider particularly:
(a) Are there any potential failures of the PES which increase the likelihood of
a particular hazardous event?
(b) Are there any potential failures of the PES which affect the protection
against hazardous events?
(c) Are there any potential failures that could produce a new hazard scenario,
or a new or more serious combination of events?
The study can be based on three documents:
(1) A list provided by the PES supplier of potential system faults, system
alarms and the actions that need to be taken. This list should be included
in section 2.2 of the Hazard Study 2 Report (worksheet m).
(2) The Programmable Electronic Systems Guide Diagram (see appendix B).
(A copy of the diagram should be included in section 2.1 of the Hazard
Study 2 Report (worksheet m).
(3) The Hazard Study 2 PES Worksheet (worksheet l) for recording results.
The completed worksheets should be included in section 2.1 of the
Hazard Study 2 Report (worksheet m).

2.3 RISK ASSESSMENT
In Hazard Study 2 undesirable events will be identified.
Their acceptability depends on their severity (or
magnitude) and their likelihood (or frequency). This
combination is the definition of risk.
Assessment of risk can be either a qualitative or
quantitative process depending upon perceived risk.
Qualitative assessment is suggested as a means to
quickly determine the potential severity of risk. As a tool
to help qualification, the team may consider the event
frequency and consequences, based upon experience
and a word model to assess the acceptability or to
determine the need for design changes or further assessments.
The objective of risk assessment, which is carried out with the Risk Matrix shown
in appendix C.2, is to decide if the risk of an event is:
(a) Unacceptable such that changes are required to reduce the risk out of
category (a);
(b) In the border region between acceptability and non acceptability, changes
may be required;
(c) No changes required.
Events will be removed from category (a) and may require a more detailed
analysis like a Quantified Risk Assessment (QRA) fault tree, to confirm the risk is
now acceptable. For an operating plant definitive action plans and scheduling will
be required to allow continuing operation.
Events in category (b) require careful examination and may require a Quantified
Risk Assessment (QRA) such as a fault tree. An action plan should be developed
and steps taken to reduce the risk.
A risk assessment procedure is given in appendix C.1.

2.4 DEFINING THE BASIS FOR SAFE OPERATION FOR TOXIC,
FIRE AND EXPLOSION HAZARDS
Having completed Hazard Study 2, the Basis for Safe
Operation for toxic, fire and explosion hazards may be
established. In this should be recorded a concise statement
of the key hazards and control measures. This can provide
a framework for future training, operating procedures,
auditing and preparation of other mandatory SHE reports.
Depending upon perceived risk, Health and Environmental
aspects may also be included.
A list of possible key measures is given in appendix D.
2.5 REVIEW OF HAZARD STUDY 2
At the completion of Hazard Study 2 the following key
activities should have been completed:
• Actions should have been assessed, reviewed and
closed out.
• All conclusions should be documented.
• All project information necessary for the completion of
the Environmental Impact
Assessment should have been assembled if necessary. Review the
Environmental Impact Assessment against any changes introduced by
Hazard Study 2
• Where the project Hazard Study 1 or 2 has identified the need, a QRA
should be completed where appropriate before Hazard Study 3.
• Identify issues that need further Hazard Study review as part of Hazard
Study 3.
The Project Manager is responsible for progressing identified actions.

Study 2: Front-End Engineering Design and Project Definition

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