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HAZOP analysis

Safe operations with expert HAZOP analysis

The Hazard and Operability (HAZOP) study is the most widely used Process Hazards Analysis (PHA) technique in the chemical, pharmaceutical, food, oil and gas, nuclear, and other process industries worldwide. HAZOP is used during the design stages of a new process or project, for major process modifications, and for periodic review of existing operations. The U.S. Occupational Safety and Health Administration (OSHA), as well as other regulators around the world, recognizes the HAZOP technique as an acceptable methodology for evaluating risk.

The quality and effectiveness of the HAZOP study depends on the leader’s experience with the HAZOP technique, as well as with the process being analyzed, with process-control systems, and with unit operations in general. Our large team of highly-qualified HAZOP leaders and process-safety experts has facilitated numerous HAZOP-based PHA’s worldwide, in virtually all sectors of the process and processing industries.

Hazard and operability (HAZOP) study - Chilworth Technology
Applications of HAZOP analysis

We can facilitate HAZOPs, and other types of PHAs, in English, Spanish, Chinese, French, German, Italian, Arabic, Hindi and other languages. Our worldwide presence helps ensure intimate knowledge of local codes, standards, and cultures. Combined with our expertise in process safety engineering, extensive laboratory and large-scale testing capabilities, interpretation of test results, and ready access to process safety data, our HAZOP capability is unrivalled in our market.

Comprehensive HAZOP studies for sustainable safety

We provide a semi-quantitative HAZOP risk analysis that incorporates the philosophies of Layers of Protection Analysis (LOPA), Safety Instrumented Systems (SIL), and Fault Tree Analysis (FTA). We use these tools to assess the reliability of process controls and number and type of risk reduction measures that might be needed.

HAZOP scenario overview - Chilworth Technology
Overview of a HAZOP scenario

We begin with a review of the available Process Safety Information (PSI) and identification of missing PSI required to support our analysis. The HAZOP study would involve the following procedure:

  • Establishing the “Design Intent” for the process, including the desired and/or safe ranges for each of the operating parameters
  • Applying the Guide Words (No, Less, More, Reverse, etc.) to each of the Process Parameters (Temperature, Pressure, Flow, Level, etc.), to identify deviations from the design intent
  • Determining if the control system and emergency systems are adequate and are sufficiently reliable to prevent each deviation from escalating to an undesirable process incident
  • Estimating the severity of the consequences of each undesired incident. Consequences can be further evaluated using our expertise in consequence modeling with specialist software such as PHAST® and Effects®
  • Estimating the likelihood of occurrence of each undesired incident
  • Utilizing a Risk Matrix to determine the relative risks of the undesired incidents
  • Comparing the risk of occurrence for each incident with corporate guidelines for process risk
  • Determining the number and types of safeguards and/or process improvements that would be needed to reduce the risks to tolerable levels

Our process safety specialist’s report will present the HAZOP team’s recommendations and suggestions for improvements to the process, based on the site’s experience and on recognized and generally-accepted good engineering practices. Following the receipt of comments from the client, a final report is issued.

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Questions and answers about HAZOP analysis

Knowing what to expect before implementing a HAZOP analysis makes for a more successful and efficient process. To that end, here are some frequently asked questions and answers about how our HAZOP studies work.

What is a HAZOP study?

The Hazard and Operability (HAZOP) methodology is a systematic team-based Process Hazards Analysis (PHA) technique that can be used to effectively identify and analyze the risks of potentially hazardous process operations. It is used during the design stages of a new process or project, for major process modifications and for periodic review of existing operations.

What is the purpose and approach of HAZOP?

The purpose of HAZOP is to prevent the release of hazardous materials and energy, followed by mitigation of the consequences should a release occur. It is essential for the team to identify all the hazards of the process being studied, not just the most obvious ones. Our approach is to use a semi-quantitative HAZOP that incorporates Layers of Protection Analysis (LOPA) to assess the reliability and number of safeguards.

What are the advantages of undertaking a HAZOP study?

HAZOP is a rigorous, structured, systematic and comprehensive method, and is adaptable to the majority of process industry operations. It fosters the exchange of knowledge and experience among the participants and enables companies to anticipate potential accidents.

Who takes part in the HAZOP team?

HAZOP is a brainstorming exercise in which individuals from different disciplines participate. It is vital for the HAZOP team to be limited in size (ideally six people or fewer, excluding the HAZOP facilitator and, if there is one, the HAZOP secretary). It is difficult to establish a maximum and minimum number of participants in a HAZOP, since the various functions necessary may be assumed in different ways in different organizations. Nevertheless, and as a very general criterion, it is safe to say that a HAZOP with fewer than three participants (excluding the HAZOP facilitator and secretary) cannot generate sufficient and meaningful discussion.

HAZOP team approach - Chilworth Technology
A typical HAZOP team approach

What information must be gathered in preparation for a HAZOP study?

HAZOP requires a review of all the available Process Safety Information (PSI) as well as identification of any missing PSI necessary for an effective HAZOP analysis. This includes, but may not be limited to:

  • Hazardous materials properties including combustibility, flammability, explosivity, reactivity, self-heating, toxicity, electrostatic properties
  • Process description
  • Process flow sheets
  • Operating procedures
  • Piping and instrumentation drawings (P&IDs)
  • Equipment design specifications
  • Pressure relief systems specifications
  • Site and industry data concerning process-component failure frequencies and probabilities of failure on demand (PFD).

How long does a HAZOP analysis take?

Estimating the duration of a HAZOP is not, of course, an exact science; it requires a good knowledge of the methodology, complexity of the process, nature of the risks that can be identified up front and, of course, the idiosyncrasy of the group. In no case should a HAZOP be carried out without an estimated agenda, but it is not acceptable for the estimation to be rigid and not subject to modification (up or down) as necessary.

What is the end product of the HAZOP study?

At the conclusion of the HAZOP analysis, our process safety specialist will present the observations, findings, and conclusions of the analysis, and preliminary recommendations and suggestions of the HAZOP team to members of the site management. Shortly thereafter, our process safety specialist will submit a written draft report to the client outlining the HAZOP team’s recommendations and suggestions for improvements to the process based on the site’s experience and on recognized and generally-accepted good engineering practices. Following the receipt of comments from the client, a final report will be issued.

What mistakes are commonly encountered when conducting a HAZOP analysis?

Firstly, planning errors can negatively impact the HAZOP study. While an estimated time frame should be in place, lack of flexibility can lead to incomplete analyses. Another pitfall is insufficient, outdated, or missing information. In order to properly identify and address potential hazards, the HAZOP team must have access to timely and complete information. A lack of focus and discipline among team members is also a common problem. Allowing outside calls and interruptions during HAZOP meetings, as well as tardiness or absences hinders the team’s progress. The so-called “minimalist HAZOP” is yet another typical mistake. This refers to superficial studies where key words or parameters are omitted, repetitions are frequent or templates are used, all of which can short-circuit the brainstorming work that allows the team to uncover less obvious risks and hazards. Finally, the “bureaucratic HAZOP” is a subset of the minimalist version. Here the process is reduced to a formulaic box-checking exercise, resulting in repetition and hampering a deeper analysis.

process hazard analysis

Prevent and mitigate process hazards and safety risks with our expert PHA services

Effectively managing process hazards in the chemical, petrochemical, pharmaceutical, metal, pulp and paper, wood, food, and process industries has wide-reaching benefits for all stakeholders, including the employees, contractors, and the public. A Process Hazard Analyses (PHA) helps prevent injury, loss of life, and property and environmental damage that can result from industrial activity and is a primary tool for compliance with regulations such as OSHA 29 CFR 1910.119 (e). PHA is a proactive and structured approach by chemical process operations to understand what can go wrong, how likely it is to go wrong and what steps are necessary to prevent or mitigate undesired consequences.

Our process safety specialists with strong industry background can help you select the PHA method best suited to your specific processes and operations. With many years of experience in process safety, we are well heeled with the complexities of hazards analysis. We can assist you in accumulating the necessary process safety information including hazardous materials properties such as combustibility, flammability, explosivity, reactivity, self-heating, toxicity, electrostatic properties as well as assembling and leading the PHA team and drawing up reports and documenting outcomes.

As part of our focus on empowering our partners in matters of process safety, we offer in-house workshops to train employees to manage risk and be effective PHA leaders.

Practical solutions are at the heart of our approach. From offices around the world, our experts focus on each client’s particular situation, taking both a holistic and an individual view of PHA implementation. Services are available in English, Spanish, Chinese, French, German, Portuguese, Italian, Arabic and Hindi, among others.

A complete range of PHA methodologies

Our specialists are experienced in the full suite of process hazard analysis methods, including checklists, what-if checklists, Hazard and Operability Studies (HAZOP), Failure Mode and Effect Analysis (FMEA), Fault Tree Analysis (FTA), Layers of Protection Analysis (LOPA) and more. As each PHA method has pros and cons as well as varying scope and application, consulting with one of our experts before making a choice contributes significantly to the overall success of your PHA.

Process Hazard Analysis - Chilworth Technology
Our Process Hazard Analysis includes these four steps.

Whatever PHA methodology is chosen, the first phase of the analysis is dedicated to gathering all the applicable safety information about the materials handled, the chemical process and conditions, the control methods employed, and the equipment and systems use. The applicable safety information relevant to the targeted process are gleaned from Safety Data Sheets (SDS’s), laboratory testing, design manuals, operating procedures, and equipment manufacturers/suppliers.

Next, a team is assembled under the guidance of an experienced, knowledgeable leader which includes members with diverse experience and expertise to examine the process in search of inherent hazards and operating risks such as fire, explosion, and the release of materials or energy. During the PHA exercise for each hazard identified the team examines the existing safeguards that prevent or mitigate the undesired consequences in addition to proposing new measures should they be required.

The final critical aspect of the PHA effort is to provide adequate documentation of the analysis, its findings and recommendations. A risk management plan must follow the PHA in order to ensure that effective follow-up and closure occurs.

Meet with one of our PHA consultants and request a quote!

FAQ - Process Hazard Analysis

Process Hazard Analyses (PHAs) comprise a wide range of methods and require a certain level of preparation. We have assembled a selection of typical questions and answers to assist you in getting ready for the process, knowing what to expect and deciding on the right approach for you.

What are the steps for preparing for a PHA?

  1. Determine the scope and scope limitations
  2. Gather process safety information, including sample testing as needed
  3. Establish team composition, including a team leader who is “knowledgeable in the specific PHA methodology being used” ([OSHA)].
  4. Provide the team with PSI several days prior to the first meeting,
  5. Schedule the meetings for not more than four hours per day, such as two hours before and after lunch.

What are the different PHA methods?

  • Checklists
  • What-If
  • What-If/Checklist
  • Hazard and Operability Analysis (HAZOP), based on ”nodes” in the P&I diagrams, or steps in the operating procedure
  • Failure Modes and Effects Analysis
  • Fault Tree Analysis [FTA]

What are the criteria for selecting a PHA method?

  • Inherent hazards of materials
  • Status of the process ([development, or design, or in operation)]
  • System complexity
  • Availability of a previous analysis
  • Applicability of good codes, standards, and RAGAGEP to the scope
  • Availability of excellent site/corporate experience, such that a well-organized What-If will likely extract all process safety issues

Do not apply a more-complex method such as HAZOP to a well-defined system that is “covered” by good codes and standards such as a flammable liquid tank farm. Do not apply a more -complex and extreme-effort-intense method such as a FTA or a QRA unless there is a “criticalprofound” decision that has to be made concerning the safety of a process.

What are the must-have qualifications of a PHA team leader?

  • Expertise and experience in PHA methodology
  • Excellent understanding of the science of hazardous materials and the consequences of releases (could be brought to the team by a subject matter expert)
  • Good understanding of “unit operations” and the uses and functions of typical process equipment
  • Good people skills to manage the team and develop consensus
  • Good organizational skills to organize and document the effort

What makes a PHA great?

  • Appropriate methodology
  • Correct application of the methodology
  • Appropriate team composition including subject matter experts as needed
  • Excellent documentation that includes why a specific method is appropriate
  • Executive summary that summarizes why the operation is safe and what major opportunities for improvement exist
  • Good team participation
  • Well defined recommendations
  • Site follow-up with documentation of recommendation closure, with attachment to the PHA report

process safety mgt

Industry Background

Of the several “approved” types of Process Hazards Analysis (PHA), the “Hazard and Operability” (HAZOP) study is the most widely used PHA technique in the chemical, pharmaceutical, oil and gas, and nuclear industries worldwide. HAZOP is used during the design stages of a new process or project, for major process modifications, and for periodic review of existing operations. This method has been found to be very effective in identifying and analyzing the risks of potentially hazardous process operations and in identifying operability problems.

The Hazard and Operability (HAZOP) analysis methodology is a systematic team-based Process Hazards Analysis (PHA) technique.

The U.S. Occupational Safety and Health Administration (OSHA) recognizes the HAZOP technique as an acceptable methodology for conducting PHA’s of processes that are covered by the OSHA Process Safety Management standard. Other regulators around the world also accept the HAZOP methodology as appropriate for analyzing the existing and potential hazards of a complex process that involves a highly hazardous substance.

Although the HAZOP method is highly structured – in the application of Guide Words to Process Parameters – in practice, the quality of the study is influenced by the ability of the HAZOP Leader to ask the appropriate questions. The objective is to ensure that the team identifies all the hazards of the process being studied, not only the most obvious hazards. Thus, the outcome of the study is based on the Leader’s experience, with the HAZOP technique, with the process being analyzed, with process-control systems, and with unit operations, in general.

Our large team of highly-qualified HAZOP leaders and process-safety resource experts has facilitated hundreds of HAZOP-based PHA’s worldwide, in virtually all sectors of the process and processing industries. Our Team Leaders are chemical and/or process engineers with a high level of process safety expertise and knowledge, and with many years of experience leading HAZOPs in industry and as consultants.

We can facilitate HAZOPs, and other types of PHAs, in a large number of languages, including English, Spanish, Chinese, French, German, Italian, Arabic and Hindi. Our worldwide presence helps ensure intimate knowledge of local codes, standards, and cultures. Combined with our expertise in process safety engineering, material-testing capabilities, interpretation of test results, and ready access to process safety data, Chilworth provides a HAZOP capability unrivalled in our market.

Moreover, through the Chilworth Process Safety Academy, we train and qualify a large number of HAZOP leaders every year. We provide HAZOP leader training through our public-enrollment courses as well as private company training, which can be tailored to our clients’ specific needs.

Our Approach

Our approach is to use a structured HAZOP to identify the hazards of a process and – as a by-product – to identify potential operating problems. The emphasis is on evaluating the basic control system, providing effective emergency controls, preventing the release of hazardous materials, and mitigating the consequences of a loss of process control or a hazardous-material release. We provide a semi-quantitative HAZOP risk analysis that incorporates the philosophies of Layers of Protection Analysis (LOPA), Safety Instrumented Systems (SIL), and Fault Tree Analysis (FTA) to assess the reliability of process controls and number and type of risk reduction measures (safeguards) that might be needed.

The general steps involved in conducting a HAZOP include:

  • A review of the available Process Safety Information (PSI) and identification of missing PSI that is required to support the HAZOP, including:
    • Hazardous materials properties including combustibility, flammability, explosivity, reactivity, self-heating, toxicity, electrostatic properties
    • Process description
    • Process flow sheets
    • Operating procedures
    • Piping and instrumentation drawings (P&IDs)
    • Equipment design specifications
    • Pressure relief systems specifications
    • Site and industry data concerning process-component failure frequencies and probabilities of failure on demand (PFD).
  • The HAZOP study would involve the following procedure:
    • Establishing the “Design Intent” for the process, including the desired and/or safe ranges for each of the operating parameters
    • Applying the Guide Words (No, Less, More, Reverse, etc.) to each of the Process Parameters (Temperature, Pressure, Flow, Level, etc.), to identify deviations from the design intent
    • Determining if the control system and emergency systems are adequate and are sufficiently reliable to prevent each deviation from escalating to an undesirable process incident
    • Estimating the severity of the consequences of each undesired incident. Consequences can be further evaluated using our expertise in consequence modeling with specialist software such as PHAST® and Effects®
    • Estimating the likelihood of occurrence of each undesired incident
    • Utilizing a Risk Matrix to determine the relative risks of the undesired incidents
    • Comparing the risk of occurrence for each incident with corporate guidelines for process risk
    • Determining the number and types of safeguards and/or process improvements that would be needed to reduce the risks to negligible or tolerable risks
  • At the conclusion of the HAZOP analysis, our process safety specialist will present the results of observations, the findings and conclusions of the analysis, and preliminary recommendations and suggestions, to members of the site management staff.

Report and Documentation

Shortly after the HAZOP team’s study, the process safety engineer will submit a written draft report to the client that will contain the results of the study, for comments by the client. Our process safety specialist’s report will present the HAZOP Team’s recommendations and suggestions for improvements to the process, as based on the site’s experience and on recognized and generally-accepted good engineering practices. Following the receipt of comments from the client, a final report is issued.

layers of protection analysis (LOPA)

Using LOPA to examine risk levels of selected scenarios

Managing process safety means understanding the many factors that contribute to risk and establishing appropriate measures for risk mitigation. Layers of Protection Analysis (LOPA) is a method used to evaluate high-consequence scenarios determining if the combination of probability of occurrence and severity of consequences meets a company’s risk tolerance. LOPA addresses the key questions: “how safe is safe enough?”; “how many independent protection layers are needed?”; and “how much risk reduction should each layer provide?”

Our process safety specialists are comfortable with complexity and experienced in implementing the LOPA methodology. We provide rational, semi-quantitative risk-based answers to key questions as well as clarity and consistency among analyses of equipment and processes at plant sites. Documentation of each decision and the decision-making process is an integral part of our methodical approach. Upon completion of the analysis, the LOPA report promotes self-sufficiency by facilitating understanding among site personnel of process hazards and their prevention.

With a strong track-record in process safety, we have carried out countless Layers of Protection Analyses, gathering valuable experience to share with our clients. We place a premium on maintaining a global presence, providing services in a wide variety of languages and having a command of the local codes, standards and cultures. Combined with our intimate knowledge of process safety engineering and process safety data, we offer expertise unrivalled in the market.

A thorough approach to LOPA services

Typically, a high-consequence scenario – which usually involves a combination of equipment and human failures – is identified during a qualitative hazard evaluation, such as a Process Hazards Analysis (PHA) or a Hazard and Operability study (HAZOP). LOPA is then implemented for a closer, more careful assessment of this scenario. LOPA is a quantitative screening tool which provides a consistent, objective, and defensible approach.

A LOPA can be visualized as a series of slices of Swiss cheese, whereby each slice is a layer of protection with a varying number and size of holes representing flaws. A high-consequence scenario occurs only if at least one of the holes in each slice “line-up,” allowing propagation of multiple failures. For components of a process-control system, such as safety instrumented systems and other components such as relief valves and rupture disks, it is important to know or estimate the probability of failure on demand.

Layers of protection analysis - Chilworth Technology
Layers of protection scenarios

We study the process under investigation to identify likely initiating events and estimate the frequency of initiating-event occurrence. We will then examine all process-control features and safeguards, estimating the reliability of protection provided and ensure the independence of each protection layer. With this information, the likelihood of occurrence (or frequency) of a given high-consequence scenario can be semi-quantitatively determined. Combining this likelihood with the severity of the consequences, an evaluation of risk is obtained.

A risk matrix is usually employed to show the possible combinations of likelihood and consequence severity. The risk thus obtained can be compared to the facility or corporation’s risk tolerance for presentation to site and/or corporate management. We prepare a comprehensive study report to serve as a record of the completed analysis, including descriptions of potential risks with the existing safeguards and with recommendations for additional safeguards, where warranted.

Let us share how our LOPA services can benefit your company. Contact us today.

process safety mgt

Ensure your company’s PSM complies with regulatory standards

As part of responsible, conscientious industrial activity, companies implement measures to ensure the safety of people, the environment and their facilities and assets. These measures can take the form of Process Safety Management (PSM), a Risk Management Plan (RMP) or some other safety program, such as the New Jersey Toxic Catastrophe Prevention Act (NJTCPA).

Our process safety specialists are dedicated to supporting safe industrial practices and have the experience and know-how to deliver quality auditing services. We can perform audits to determine conformance to OSHA – Occupational Safety and Health Standard (29 CFR 1910.119), Process Safety Management of highly hazardous chemicals, EPA’s risk management rule (40 CFR Part 68), chemical accident prevention provisions, the NJTCPA Consolidated Rule, or your corporate process safety standards and programs.

Not only do our auditors have the expertise, credentials and background to ensure dependable, professional results, but we also have the soft skills to make partnering with us a successful experience in every way. Our emphasis on good communication and friendly collaboration is paired with a global scientific rigor, all in the service of safety.

A three-step auditing process for PSM plans

Our process safety audits follow a three-step process beginning with information collection prior to a site visit followed up with a report and documentation.

Compliance auditing for process safety
Compliance auditing process for PSM

Our process safety specialists work closely with site personnel to collect pertinent Process Safety Information (PSI) required for the audit. Time spent on this activity helps to minimize the time required for the on-site visit. Information needed may include process descriptions and flow diagrams, material property data, site equipment layout drawings, and written policies and procedures.

In the second step, we shall conduct the site audit. During this visit, we complete record reviews, make visual observations, and conduct interviews with site operations and maintenance personnel as well as contract personnel in order to assess compliance. For OSHA, EPA, and NJTCPA compliance, a detailed checklist is completed addressing all aspects of the standards.

Finally, we shall submit a written report to the client that contains our findings, checklists, observations, and suggestions concerning any gaps found in the PSM, RMP, and/or NJTCPA covered portions of the site. We offer insight and recommendations as may be required to advance the site’s programs based on the legislated requirements and best industry practices.

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Laboratory Testing

lab testing

We operate one of DEKRA's world premier chemical process hazards laboratories. Process safety testing is used to develop the data on which fire and explosion hazard assessments and incident investigations should be based.

Learn about our Laboratory Testing options