Preparing for a HAZOP

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Preparing for a HAZOP study

An effective HAZOP study relies on the right preparations being made prior to undertaking the HAZOP workshop. The following article provides an overview of the steps to take and pitfalls to avoid when organising a HAZOP study.

Hazard studies can be undertaken at different stages throughout the design process. For instance, a Hazard Identification (HAZID) study may be more appropriate at early/concept stage of a design to uncover significant hazards that may inform the design. HAZOP studies are usually carried out at detailed design stage when the P&IDs are finalised to systematically review the potential hazards and operability issues of the proposed designs. The decision to carry out a HAZOP study may be based on internal company practice or imposed by the client / external regulatory bodies. In the latter case, the project supervisor should contact the client to obtain any HAZOP guidance or procedure documentation they may have for applying the HAZOP technique to their assets. In the absence of a specified HAZOP methodology, the HAZOP: Guide to Best Practice Third Edition remains the HAZOP guide of choice for the chemical and process industries.

Appointing a HAZOP Chair

A HAZOP Chair or Team Leader should be appointed at the early stages of HAZOP planning. The role of the HAZOP Chair is to facilitate the HAZOP process and guide the HAZOP team through the HAZOP study. The appointed HAZOP chair should be experienced in HAZOP facilitation and possess a solid understanding of process design. It is also important that the HAZOP chair is independent so as to avoid imparting bias, e.g. from previous involvement in the project.

Interpersonal communication is a core aspect of HAZOP workshops which the HAZOP chair must navigate. HAZOP meetings are often attended by several stakeholders with differing perspectives, expertise, and interests. A core task of the HAZOP chair is to encourage a balanced discussion from the team members and promote a collaborative approach to problem solving while ensuring that the HAZOP process is adhered to.

Scribe

The scribe is responsible for recording the HAZOP study and so should be familiar with the HAZOP method with a working understanding of the subject matter. Typically, HAZOP studies are recorded on proprietary HAZOP/PHA software or Excel spreadsheets which provide a template for inputting the findings of the study in the correct format. While the HAZOP chair may also fulfill the role of scribe, this not recommended as they cannot effectively engage in discussion and record at the same time. The appointed HAZOP chair will usually provide a dedicated scribe as part of the HAZOP facilitation services. The task of the scribe is to summarise the consensus of the team in a concise manner with instruction or amendments from the HAZOP chair as necessary. Over the course of the study, the HAZOP spreadsheet is usually displayed on a projector or large TV screen to allow the study team to view and agree on the record as it is being updated.

Pre-HAZOP Meeting

On appointment of the HAZOP Chair, the contractor, client, and HAZOP chair should arrange a pre-HAZOP meeting to review the design documents and outline the scope of the HAZOP study. During this meeting the chair will ascertain the ‘firmness’ of the design to satisfy himself that the design has been sufficiently progressed to undertake a detailed HAZOP study. The P&IDs will be reviewed to identify Nodes to be studied. Nodes are individual lines of the system with a defined design intent to which HAZOP guidewords are applied. The HAZOP chair will advise on the anticipated number of sessions required to complete the HAZOP study based on the extent of the works and previous experience. The process parameters to be reviewed and method of recording (i.e. recording in full or by exception) should also be agreed at this stage.

HAZOP Scheduling & Venue

The contractor will liaise with the client to arrange a suitable date and venue for the HAZOP meeting. Ideally, HAZOP sessions should be limited to half-days, with no more than three sessions per week. HAZOP studies require sustained concentration and once fatigue sets in amongst the study team the quality of the HAZOP tends to suffer. Regular tea breaks should be worked into the agenda. Selection of a venue should consider the following:       

  • The meeting room should be sufficiently sized for the anticipated numbers to sit comfortably with adequate table space for drawing printouts.
  • A large TV screen or overhead projector should be made available such that the HAZOP spreadsheet and drawings are visible to all in the room. 
  • The venue should be free from distractions and ideally remote from the site of the works under review.
Who Should Attend a HAZOP Study?

The client will usually be responsible for issuing invitations to the required HAZOP study team members. The size and composition of a study team will depend on the project under review, however, there is usually a core team of six to seven people comprising the following roles:

  • HAZOP Chair/Team Leader
  • Scribe
  • Project Manager
  • Design Engineer
  • Plant Operator
  • Client HSQE
  • Client’s Representative

Where proprietary or specialist equipment are included in the design it is beneficial arrange for a representative from the supplier to attend the HAZOP while this system is under review. There is often a temptation by the client and contractor to issue invitations to large numbers of personnel involved in a project where their attendance at HAZOP is not required. For instance, it is not necessary for three project engineers to attend the HAZOP study on behalf of the contractor if the lead design engineer has a solid grasp of the process design. There is rarely a requirement for more than ten attendees, and as numbers increase beyond this point the quality of the HAZOP can deteriorate. It becomes increasingly difficult to direct the focus of the team on the HAZOP process, conflicts can emerge, and separate conversations may take place amongst team members.   Overall, the assembled study team should have the necessary combined experience and knowledge to properly evaluate the design and its anticipated process and operational issues.

Documentation

The HAZOP study team should be issued the required HAZOP and design documentation prior to the HAZOP study. These documents should be issued in a timely manner so that the team have an opportunity to review the proposed design in advance of the HAZOP study. The HAZOP Pack should include the following documents:

  • P&IDs
  • Sit Layout, General Arrangement Drawings
  • Draft Control Philosophy
  • Process Flow Diagram
  • HAZOP Study Format, Terms of Reference
  • HAZOP Nodes
  • HAZOP Agenda

It is important that the P&IDs are sufficiently developed for the HAZOP as they will form the basis of the HAZOP review process. Furthermore, the P&IDs should be ‘frozen’ and no further revisions made in the lead up to the HAZOP study.