HAZOP Study Checklist Template

The study leader sets up the study about five weeks before the first session. The first task names the five people, the kind of study and the rules the site works under, and gives the first and last session dates: tasks before the sessions count back from the first, and everything after them counts forward from the last, in working days.

• Set up the HAZOP study — the site, unit and process, the study reference, what kind of study it is, which rules apply, the first and last session dates and the five people; later tasks are assigned and dated from these fields
• Define the scope and the study boundaries — what the study covers and what it leaves out, the battery limits and tie-in points, the connections to other units and utilities, and the operating modes to examine: normal running, start-up, shutdown, maintenance and emergencies
• Link the study to its change record — the MOC or project reference, what is changing, and where the changed plant meets plant that stays as it is, so that the nodes cover the tie-ins
• Review the previous study and what has changed since — the last HAZOP report and its date, how each of its recommendations was closed, the changes made to the process since, and the incidents and near misses since; the team checks that the study still matches the current process
• Record the design intent and the operating envelope — what the process is meant to do, the design basis, the normal operating ranges and the safe limits for flow, pressure, temperature, level and composition, and the materials handled and their hazards
• Confirm HAZOP is the right method — why a HAZOP suits this process, whether operating steps need a procedure HAZOP, and any later study it will feed, such as a layer of protection analysis

The design lead and the study leader divide the process into nodes on the P&IDs and agree the parameters and guide words. The node list sets how many session days the study needs.

• Mark up the nodes on the P&IDs — divide the process into sections that each have one design intent, number them in the order of the flow, and mark them on a copy of each P&ID
• List each node with its design intent — the node number, a short description, the P&IDs it covers and what that section is meant to do; the scribe uses the same numbers on the worksheets
• Choose the parameters and guide words — the parameters for each node, such as flow, pressure, temperature, level and composition, and the guide words the team will apply to them, such as no, more, less, as well as, part of, reverse and other than; add timing and sequence words for batch steps
• Plan the session days — how long each node is likely to take, how many hours a day the team will sit, and the dates of each session; if the plan needs more days than the dates on the first task allow, change the last session date there

The team needs the people who designed the process, the people who run and maintain it, someone who knows process safety and a leader who knows the method. The study leader names them, checks the skills and books the sessions.

• Name the study team — the study leader, the scribe, a design or process engineer, an operations representative who knows this process, maintenance and instrument engineers, a process safety specialist, and anyone else the scope needs, such as a control systems engineer or the equipment supplier
• Check the team has the skills the study needs — the leader’s HAZOP training and experience, each member’s knowledge of the process, and cover for anyone who cannot attend every session; record any gap and how it is filled
• Book the sessions and set up the recording — the room or video call, a screen for the drawings, the worksheet template or software, and calendar invitations for every session

A HAZOP is only as good as the drawings it uses. The design lead checks the drawings against the plant or the latest design, then freezes the revision the team will study; the study leader gathers the safety information, past incidents and the site’s risk matrix, and sends the pre-read.

• Check the drawings against the plant as built — for existing plant, walk the plant with the drawings and mark every difference; for a new design, confirm each drawing is the latest issued revision; differences are corrected before the drawings are frozen or recorded as a study assumption
• Freeze the drawings and study documents — the P&IDs and their revisions, the process flow diagram, the heat and material balance, cause and effect charts, relief and alarm data, data sheets and any draft operating procedures, frozen at the revision checked in the previous task with its corrections; nothing in the frozen set changes during the sessions
• Gather the process safety information — safety data sheets for the materials, reactivity and compatibility data, the technology and design basis, and the equipment information, so the team can understand the hazards
• Collect past incidents and lessons — incidents and near misses on this process or similar ones, here and elsewhere in the company, and published lessons for the same materials, for the team to use when it judges causes and consequences
• Agree the risk matrix and ranking rules — use the site’s own risk matrix and say which version; agree how the team ranks severity and likelihood, and which rankings need further analysis; this template does not set the values
• Brief the team and send the pre-read — the scope, the node list, the frozen drawings, the risk matrix and how the sessions will run, sent a few days before the first session

The team works through each node in turn. For every parameter and guide word it records the deviation, its causes, what could happen, the safeguards already there, the risk ranking and any recommendation. The scribe keeps the worksheets, and they are read back after the last session.

• Open the first session — introduce the team, read back the scope, design intent and boundaries, explain the guide words and the risk matrix, and agree the session rules
• Examine each node with the guide words — apply each guide word to each parameter, decide whether the deviation is credible, and finish one node before moving to the next; a deviation with no credible cause is recorded as considered
• Record the causes and consequences — for each credible deviation, every cause the team finds and the worst credible consequence if no safeguard worked, to people, the environment and the plant
• Record the safeguards already in place — alarms, trips, relief devices, interlocks, procedures and other protection in the design or on the plant, and whether each is independent of the cause; protection the design does not yet have is a recommendation, not a safeguard
• Rank the risk of each deviation — severity and likelihood with the safeguards in place, using the risk matrix agreed in Phase 4, and a flag on each deviation that needs further analysis
• Raise recommendations and questions — each recommendation numbered and linked to its node and deviation, saying what should change and why; a question the team cannot answer in the room is recorded with who will answer it
• Cover the RMP additions to the analysis — stationary source siting and the proximity of the public, natural hazards, standby or backup power for the monitoring equipment, and any gaps between the codes the process was built to and their current versions
• Consider safer technology and alternatives — for a covered process in NAICS code 324 or 325, consider and document inherently safer technology or design, passive measures, active measures and procedural measures, in that order of preference
• Keep the attendance and session record — who attended each session, the nodes covered each day and any session held without a key discipline, so the record shows who took part
• Read back the worksheets with the team — the scribe sends the worksheets after the last session and the team confirms they record what was agreed; corrections are made before the actions are assigned

After the sessions the study leader closes the open questions, gives every recommendation an owner and a target date, decides where more analysis is needed, tells the people the actions affect, and the study sponsor records any recommendation not adopted as written. These steps come before the sign-off, whatever its outcome.

• Answer the open questions from the sessions — each question answered by the person named, checked with the team, and either closed or turned into a recommendation
• Give every recommendation an owner and a target date — the written schedule of what is to be done, by whom and by when, with the priority from the risk ranking; the register here is the one later tasks update
• Decide which deviations need further analysis — for example a layer of protection analysis, a quantified risk assessment or a safety integrity level assessment, where the ranking or the team’s judgement says the safeguards may not be enough
• Tell the people the actions affect — operators, maintenance staff and others whose work is in the process and who may be affected by the recommendations or actions, through briefings, shift handovers or toolbox talks
• Check what the study means for the COMAH documents — whether the findings change the major accident prevention policy, the safety management system’s hazard identification, the safety report of an upper tier site, or need a notification to the competent authority
• Record any recommendation not adopted as written — each recommendation the study sponsor decides not to adopt as written, with what will be done instead or why it was rejected, the evidence for that decision and who made it; this template asks the sponsor to decide before signing off the action plan

The study leader writes the report and the team checks it. The study sponsor then signs off the study and its action plan; nothing after the sign-off can be completed until the sponsor completes it.

• Write the HAZOP report — the scope and boundaries, the team and attendance, the drawings and revisions studied, the method, guide words and risk matrix, the node list, the worksheets, the recommendations with owners and dates, the assumptions and anything left open
• Send the draft report to the team for comment — each member checks that the report records what was agreed in the sessions; comments are answered and the report updated
• Rework the study before it is signed off — make the changes the study sponsor asked for, which may mean more sessions, and complete this task; the sponsor then changes the decision on the sign-off task to Approved or Approved with conditions, which hides this task, and completes the sign-off
• Sign off the HAZOP study — the study sponsor reads the report and the action plan and completes this task with the decision: Approved, Approved with conditions or Not approved

Applies only when the study is signed off (Approved or Approved with conditions). Once the study is signed off, the report becomes the record of the study. The revalidation date is set now, and each recommendation is tracked until it is done.

• Meet the sign-off conditions — do what the study sponsor asked for when approving with conditions, and record how each condition was met
• Issue the final report and file the study record — the signed report, worksheets, attendance, frozen drawings and action plan filed together where they can be found for the life of the process, and the team told where they are
• Set the revalidation date — the date the study is next updated and revalidated, entered here so it can be tracked, set from your own procedure and the law that applies
• Track each recommendation to closure — update the status of each recommendation in the register as it is done, chase anything past its target date, and agree any new date with its owner
• Update the drawings, safety information and procedures — every drawing, data sheet, operating procedure and piece of process safety information the actions change, updated through the site’s change process

Applies only when the study is signed off. Close-out checks that what the team asked for was really done. The study closes when every recommendation is closed or carried into another tracked process.

• Check on the plant that each closed action was done — walk the plant or review the design to confirm each change, hardware and software included, is in place and does what the team intended
• Confirm the actions needed before start-up are closed — for a new unit or a change, the actions the team said must be done before start-up are closed or the start-up waits; for a revalidation of running plant, mark this task not applicable
• Close the study — every recommendation is closed or carried into another tracked process, the register is final and the revalidation date is in the site’s planning system