ExploConsult Process Hazard Analysis

HAZOP’s are a set of studies that can be carried out on new or existing
processes or on modifications, to ensure that the hazards of the process
are understood and adequately controlled. The technique applied depends
on the stage of the study; some studies will use a guide diagram approach
to identify hazards and others will be based on a checklist approach.

They are studies carried out by application of guidewords to identify all
deviations from design intent with the potential for undesirable effects
​on safety, health, the environment or operability.

​With that said, there have been many variations of ANFO and Emulsion plants installed around the world that may, or may not, have been subjected to a Hazard Review. Particularly mixers, pumps and control systems must be looked at to ensure the compatibility with the safety, health and environmental aspects of first of all management, and of course the governmental regulations. The entire process and plant should be subjected to a series of hazard reviews by a team of experienced professionals to ensure that a physical situation with a potential for human injury, damage to property, damage to the environment or some combination of these
does not exist.


The Hazard Study process has evolved since the 1960’s, to identify and correct Safety, Health, and Environmental (SHE) hazards. The process is general, and appropriately adapted and applied will recognize deficiencies in other systems such as quality, financial, and general operability. The Hazard Study Methodology that will be employed can be used to satisfy the 29 CFR (OSHA) 1910.119 requirements for Process Hazard Analysis and pre start-up safety review of hazardous processes.

Hazard Study 1
The purpose of Hazard Study 1 is to ensure that the understanding of the project, the process and the materials involved is sufficient to enable safety, health, and environmental issues to be properly assessed. It also contributes to key policy decisions and ensures that contacts are established with the functional groups, site management, and the authorities that may contribute to, or impose constraints upon, the development of the project.

Key aspects include:
1. Clear understanding of the project scope.
2. Reviewing information on any previous incidents involving similar technology.
3. Collecting information on the safety, health and environmental hazards of all chemicals and materials involved.
4. Provide a broad appreciation of the hazards of fire, explosion, and harmful releases as they apply to the inherent SH&E protection.
5. Reviewing the Environmental Impact Assessment to ensure that it will cover all relevant on-site and off-site environmental issues.

Hazard Study 2
The purpose of Hazard Study 2 is to identify significant hazards and ensure that there appropriate measures to eliminate the risk or reduce the risk to tolerable levels.

Key aspects include:
1. Consideration of any impact (SHE), which the project may have on either on-site or off-site.
2. Identification of significant hazardous events with special attention being paid to loss of containment which could lead to toxic, flammable,
biological, or explosive hazards to employees or the public, or to environmental pollution.
3. Identification of changes to process conditions that could lead to the consent levels for gaseous, liquid, or solid effluents being exceeded.
4. A review of the measures proposed to prevent employees being exposed to either chronic or acute health hazards.

Hazard Study 3
he purpose of Hazard Study 3 is to review the design and/or procedures to identify any hazards or obstacles to operability, which could arise, particularly through deviations from the design intent. In the case of a process plant (in this case) this will be based on the study of firm Engineering Line Diagrams and the outline operating procedures and outline commissioning procedures. The consequences of deviations are identified and where necessary, appropriate corrective actions initiated.

The study also provides an opportunity to review potential maintenance and quality problems.

Key aspects include:
1. A detailed systematic study of the design and outline operating and maintenance procedures to identify the consequences of deviation from
the design intent.
2. Consideration of transient operating conditions during start-up, shut-down, plant upsets and emergencies.
3. Consideration of potential exposure of employees to harmful effects during routine operations including maintenance, decontamination, etc.

The Hazard Study 3 is the “HAZOP” technique as referred to in US Federal Legislation on Major Hazard Plants, OSHA 29CFR Part 1910 and specified in the AIChE, Centre for Chemical Process Safety “Guidelines for Hazard Evaluation Procedures”.

Hazard Study 4
The purpose is to check that the project has been constructed as the design intended, and that the actions of previous Hazard Studies have been completed and implemented in the design and installation.

To check that the operating instructions and emergency procedures comply with any requirements identified by previous Hazard Studies and are satisfactory for safe operation.

​Key aspects include:
1. Actions from earlier have been completed, or that changes have been justified.
2. All actions and changes have been documented.
3. Operating instructions are available for normal operation, start-up, planned and emergency shut-downs and, where appropriate, for
maintenance and decontamination of the plant.
​4. Emergency procedures are available.

Hazard Study 5
The purpose of Hazard Study 5 is to provide an opportunity for those responsible for personal safety, employee health and environmental protection on the site to satisfy themselves that the detailed implementation of the project meets Statutory, Company and legislative requirements.

Key aspects include:
1. A review of the arrangements for the protection of employee health, covering the facilities provided and the arrangements for workplace
2. A review of the arrangements, including emergency systems, for employee safety.
3. A review of the equipment and systems provided to protect the environment and for monitoring environmental performance.

Hazard Study 6
The purpose is to check that Hazard Studies 1 to 5 have been completed, and relevant documentation exists in the Project SHE Dossier.

To review early operation to ensure that it is consistent with the design intent with regard to safety, health and environmental issues, and that assumptions defined in earlier Hazard Studies are borne out in actual operation.

To identify and record operating and maintenance difficulties, and report back to the project management. THE HAZARD STUDY TEAM

The Hazard Study Team should consist of:
a) A Hazard Study Leader
b) A Project Manager
​c) A Site Representative
​d) A Functional (design) engineer
e) Specialists

Hazard Study Leader
The leaders function is to lead the discussion, encouraging thinking about what might go wrong, and what that would result in. The Hazard Study Leader should have had training and experience compatible with the complexity and hazards of the process being studied.

Project Manager
The Project Managers role is to choose the hazard study team, coordinate the hazard study meetings, review the design to ensure that the process meets the Safety, Health and Environmental targets set my management. He also has the responsibility to ensure that the study is recorded properly, and that all action items are properly completed and recorded.

Site Representative
Accepting the operating principles, constraints or procedures agreed at the Hazard Studies including implications on manning levels, maintenance procedures, etc.

He also needs to understand the basis for safe operation and the hazard control philosophy, so that he can satisfy himself that any changes made at commissioning, or subsequently, do not increase the hazards of the operation. He is the person that ensures that all action items are completed, the rest of the employees are fully trained in the safety aspects of the operation, and that no changes can be made without the proper study, acceptance by management and proper documentation.

Where their particular expertise is needed, other members can be invited to specific meetings. For instance, this may include a control engineer where complex control systems or computer controls are involved. His role should include consideration of the practical aspects of routine proof testing and classification of electrical systems.

The Hazard Study Leader needs to ensure that the team assembled has the necessary operating experience and process knowledge, which can be provided by a plant supervisor or other appropriate personnel.


Hazard Study 1
Performed during the project feasibility study, it identifies the basic hazards of the of the materials involved and of the operation. It establishes Safety, Health and Environmental criteria and ensures the necessary contacts with functional groups and external authorities.

For projects with no inherent hazard, the study process may be curtailed following Hazard Study 1 at the discression of the Hazard Study Team. In these cases, the reasons for not following the full procedure should be fully documented.

Hazard Study 2
Performed at the project definition stage, using Guide Diagrams to stimulate creative thinking to identify significant hazards. Inherent SHE principles continue to be applied where possible and practicable, or assessment may be used to determine appropriate design features, including the identification of trip/alarm systems.

Hazard Study 3
This is a Hazard and Operability Study, sometimes called “HAZOP”. It is performed at the end of the project design stage, using fully developed P&ID’s to identify hazards and operability problems, using guidewords to stimulate creative thinking about possible deviations
​and their effects.

Hazard Study 4
Performed at the end of the construction stage and before introducing process materials, this checks that the equipment and procedures are as required by the previous hazard studies.

Hazard Study 5
Performed at the end of the construction stage and before introducing process materials, this is a check that the project meets Company and legislative requirements.

Hazard Study 6
Performed 3 to 6 months after beneficial production is established, this study checks that previous Hazard Studies have been completed and that early operation is consistent with the design intent and with the assumption in earlier Hazard Studies.