Introduction to Hazard Studies

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Process Safety Guide: GBHE-PSG-HST-001

Introduction to Hazard Studies

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Process Safety Guide: Introduction to Hazard Studies CONTENTS 1 INTRODUCTION 2 HAZARD EVALUATION TECHNIQUES

2.1 Hazard Identification and Control 2.2 Selection of Technique 2.3 GBHE Hazard Study Procedure 2.3.1 Study One – Concept stage hazard review

2.3.2 Study two - Front-end engineering design and project definition

2.3.3 Study three – detailed design hazard study 2.3.4 Study four – construction/ design verification 2.3.5 Study five – pre-commissioning safety review 2.3.6 Study six – project close-out/ post start-up review

2.4 Application of Hazard Study Procedure

2.5 Outcomes from the Process 2.6 the Hazard Study Toolkit

2.7 Change Management/Modifications 3 HAZARD STUDY LEADER CAPABILITY AND APPOINTMENT REFERENCES APPENDICES A THE PROJECT PROCESS B GBHE HAZARD STUDY TOOLKIT



1 INTRODUCTION Hazard studies are required for the identification of hazards and the assessment of risks for all new or significant modifications of processes, plants, equipment and buildings. Appropriate hazard studies should be performed at various stages from early development through to beneficial manufacture and final closure. They are also required for periodic review of hazards as part of ongoing SSHE assurance. This document describes the ‘GBHE’ hazard study toolkit’ and contains guidance on:

• techniques for the evaluation of hazards and the use of the hazard study procedure;

• use of hazard studies in management of change/modifications;

• Hazard study leader capability and appointment. It does not cover the identification and control of product hazards. Who is it intended for?

• Managers responsible for the selection and appointment of hazard study leaders.

• Site Responsible Engineers or managers responsible for local procedures on hazard evaluation procedures.

• Hazard study leaders and hazard study participants.

• Project managers.

• Persons responsible for the examination and approval of modifications.

This guidance supports the requirements of the Responsible Care Management Systems. (RCMS) and will assist with the implementation of SSHE Guidelines and GBHE Engineering Procedure GBHE_PSG_EP_6. A glossary of terms used can be found in Process SHE Practitioner Guide GBHE-PGP-003/008.



2 HAZARD EVALUATION TECHNIQUES 2.1 Hazard Identification and Control It is important that all significant hazards are identified and satisfactorily controlled if they cannot be removed or eliminated. The depth of hazard identification and risk assessment and the methodology used should be appropriate to the risk to safety, security, health, the environment or business. Where appropriate, screening criteria should be used in order to identify those hazards or risks that require more detailed assessment or additional management measures. A hierarchical approach to risk management should be followed by exploring practical opportunities to:

2.2 Selection of Technique The hazard assessment technique selected and the depth of study required needs to be relevant to the hazards involved and the risks to be managed for the business and location. In determining the hazard study technique to be used, judgments have to be made. It is recommended that local guidance is prepared to assist managers who make these judgments . Techniques may be generally classified into two types: Task based and Process or Equipment based:

• Task based techniques include Job Safety Analysis and Task Analysis. These are a systematic approach to breaking a job / work task down into its component parts and identifying the hazards associated with each part of a given job. Guidance on the use of all these techniques can be found in Process SHE Practitioner Guide GBHE-PGP-005.



• Process and Equipment based analysis include techniques such as process hazard analysis, Checklist Analysis, What-if Analysis, FMEA (Failure Modes and Effects Analysis) and Quantified Risk Analysis (QRA). Process hazard studies are required when plants, equipment, buildings or processes are new or altered.

The recommended GBHE process hazard study procedure uses six stages and is similar to that described in chemical process safety publications such as 'HAZOP: Guide to best practice' and ‘Guidelines for Hazard Evaluation Procedures’. This procedure can be applied to both continuous and batch plant processes. 2.3 GBHE Hazard Study Procedure The recommended GBHE hazard study procedure is summarized below. Not all of the stages described may need to be covered in every application: 2.3.1 Study one - Concept stage hazard review

In this first study, the basic hazards of the materials and the operation are identified and SHE criteria set. It identifies what information is needed and the program of studies required, ensuring that all safety, health and environmental issues are adequately addressed. The aspects covered may include reaction kinetics, toxicity data, environmental impact and any special process features that need further evaluation. In addition, any constraints due to relevant legislation are identified. A decision may be taken on which of the remaining hazard studies (two to six) should also be undertaken. It is also important at this stage to apply the principles of inherent SHE within the design. 2.3.2 Study two - Front-end engineering design and project

definition This study typically covers hazard identification and risk assessment, operability and control features that shall be built onto the detailed design, and any special environmental features to be covered. Potential for loss of containment will also be identified. Alarm and trip systems can be considered here and inherent SHE principles continue to be applied.



2.3.3 Study three - detailed design hazard study This normally involves a detailed review of a firm design aimed at the identification of hazard and operability problems. Relief and blowdown studies, area classification, personal protection and manual handling may, if appropriate, be included at this stage. HAZOP studies are normally carried out at this stage. HAZCON or HAZDEM studies are sometimes carried out at this stage. 2.3.4 Study four - construction/design verification This review is performed at the end of the construction stage. The hardware is checked to ensure it has been built as intended and that there are no violations of the designer's intent. It also confirms that the actions from the detailed design hazard studies 1, 2 and 3 are incorporated, and operating and emergency procedures are checked. 2.3.5 Study five - pre-commissioning safety review This examines the preparedness of the operations group for start-up and typically covers training, the final operating procedures, preparation procedures and readiness for start-up including function testing, cleanliness and purging. Confirmation of compliance with company and legislative standards is done at this stage. 2.3.6 Study six - project close-out/post start-up review This study, carried out a few months into the production phase, confirms that all outstanding issues from the previous five studies are complete and seeks any lessons that might give useful feedback to future design work. In practice, some studies may be combined, for example with small projects or modifications. A Periodic Hazard Review (PHR) may be carried out periodically on existing plant using Hazard Study 1 and 2 methodologies.



2.4 Application of Hazard Study Procedure In determining the extent of hazard studies necessary, and the method to use, note the following:

• For capital projects a multi-stage approach should be used that matches the stages of the project process and project development. See appendix A for a typical project process and the relationship with the hazard study stages.

• When a significantly new process is being developed and for all process

development projects a Hazard Study 1 should be carried out as soon as possible for a basic identification of hazards. If the study demonstrates that there are no significant hazards, it may be agreed that no further hazard studies will be necessary. For most projects with significant process hazards and complexity, Hazard Study 2 and a specific detailed design stage study (e.g. HAZOP or similar) should be carried out.

• For major and high hazard processes, a full series of specific hazard

studies covering initial design through to and including ongoing operation stages should be carried out for new plants and for modifications or extensions to existing plants.

• There may be requirements in local legislation for HAZOP studies, PHRs

and pre start-up reviews. For example, legislation in Europe to implement the Directive 96/82/EC on the control of major accident hazards involving dangerous substances; in the USA, the OSHA Process Safety Management Standard and EPA Risk Management Program. Hazard studies meeting the requirements of the GBHE guidance should normally be sufficient to satisfy such statutory requirements.

• Local procedures should ensure that a hazard methodology is applied to

all change management/ modification projects. Changes to existing processes, buildings, plant and equipment, need to be registered and controlled. Each change or modification should be reviewed and a decision made as to the requirement and extent of hazard study. Modifications with significant process hazards and complexity should be treated as projects and receive a full series of hazard studies.



• The frequency of PHRs should also be relevant to the hazards involved.

For plant with significant process hazards, a review should be made at least once every five years (that will be a statutory requirement for plants in a number of countries). Longer periods between reviews may be appropriate for plants of lesser hazard or risk and in some cases more frequent reviews may be necessary.

2.5 Outcomes from the Process

The process of hazard identification and risk assessment will result in an understanding of hazards and their potential consequences. In practical terms the outcomes will include:

• identification of hazards and their elimination or minimization;

• implementation of required protection by appropriate physical changes, procedural measures and controls;

• identification of critical equipment and the need for critical safety

instrumented systems, schedules of routine inspection and testing and equipment records;

• Worksheets and actions which are summarized into a hazard study report

that provides a record of the decision processes and risk management requirements at each stage of the process. Full completion of documentation is recommended and is often a regulatory requirement.



2.6 The Hazard Study Toolkit GBHE guidance on the hazard study process is summarized in appendix B - The GBHE Hazard Study Toolkit. This consists of:

• Practitioner guides for trained hazard study leaders – this includes

guidance on each stage, worksheets and specialist techniques. Guidance on training and validation of leaders is also included.

• GBHE Process Information – this should include key contacts and examples of hazard study application. A list of validated hazard study leaders should be included.

• Standardized hazard study worksheets.

• Chemical process safety publications such as 'HAZOP: Guide to best

practice' 2.7 The Hazard Study Toolkit A change to an existing facility or the way it is operated requires a modification procedure. Any procedure developed to identify and control the hazards arising from modifications needs to be: (a) Flexible in its ability to handle minor modifications to large complex

modifications; (b) Effective in identifying hazards including obscure hazards; (c) Simple to understand and apply, and encourage employee participation. An example local procedure for the control of modifications is available in the guidance documentation. See Process SHE Practitioner Guide GBHE-PGP-006. Modification procedures fall under GBHE SSHE GBHE-PGP-006.



3 HAZARD STUDY LEADER CAPABILITY AND APPOINTMENT A formal program of training and experience is required for validated GBHE hazard study leaders. Details of the training and validation process may be found in the hazard study toolkit documentation. See Process SHE Practitioner Guide GBHE-PGP-007. Key appointments are defined in GBHE_PSG_EP_1. The responsibilities of the Site Responsible Engineer, Project Manager, Hazard Study Leader, Operating Manager and Commissioning Manager respectively are described in GBHE_PSG_EP_6. Businesses may have their own equivalent business engineering procedures for implementation of the GBHE_PSG_EPs. REFERENCES Books 'HAZOP' Guide to Best Practice, published by IChemE Guidelines for Hazard Evaluation Procedures, published by CCPS



APPENDIX A THE PROJECT PROCESS

Introduction to Hazard Studies

Documents

Transcript of Introduction to Hazard Studies