HAZOP Process

A HAZOP study can be broken down into the following steps (McKelvey (1988))  

Gather the information necessary to conduct a thorough and detailed study. 

Subdivide the process into logical, manageable sub-units for efficient study and confirm that the scope of the study has been correctly set. 

Conduct a systematic review according to the established rules for the procedure being used and ensure that the study is within the special scope. 

Follow up to ensure that all recommendations from the study are adequately addressed. 

---

What the HAZOP Does. The HAZOP process is there to identify those situations which the designer has forgotten or ignored and which could lead to a hazard. It often will be looking for complex and abstruse failures and situations and rare events. It should be borne in mind that even rare events can represent considerable risks (recalling that risk is a combination of the consequences of an event and its likelihood). Despite often bad publicity, the chemical industry is a very safe one and rare events need to be addressed. 

During the 1960s, ICl developed the HAZOP (Hazard and Operability) process to identify hazards in chemical plant design. The HAZOP process is now well established, and was successfully... 

Purpose and scope (defines the objective and appiicabiiity of the HAZOP) Process review team... 

The Hazop process itself is likely to be compromised. If it is swamped under the volume of problems which surface, the chances of picking up all the problems are significantly decreased. This is analogous to one of the scenarios that a Hazop should bring to light if a safety device, such as a safety valve, can be used by the plant operators in normal plant operation (rather than taking direct action to prevent an over-pressure), the reliability of the safety system will be unacceptably reduced. In fact, if the Hazop comes up with too many problems, it must be repeated after the modifications have been made. 

It is quite some time since various methods were developed for automating the HAZOP process. Some methods included computer-based systems. We shall now see how these systems have been developed. 

HAZOP expert is an object-oriented model-based intelligent technique used to automate the HAZOP process. It is well known that no two plants are identical, hence the problems will be different. At the same time it is also true that the majority of time and effort is spent on routine work in a HAZOP study and there is commonality in this routine work. So, by automating this routine part (which is a major part), time, effort, and cost can be saved. But how can this routine work be matched with plant-specific issues Another important issue to be noted is that automation is not meant to replace the HAZOP team but to supplement it, so that experts instead of being bogged down with routine work can concentrate on how to address the complex issues pertinent to the plant. To understand HAZOP expert it is better to refer to Fig. lV/1.6.2-1. 

Taking the above stated differences between the What-If Analysis Worksheet and the HAZOP process. Figure 14.3 provides an example of a typical HAZOP Worksheet. Note the headings over each column. Some are identical to those found on the What-If worksheet and, therefore, transfer of the information from any previous What-If... 

GENERAL (general information about the project, process, or facility) COMPANY POLICY (statement of company ES H management policy) PURPOSE SCOPE (defines the objective and applicability of the HAZOP) PROCESS REVIEW TEAM... 

One team member should take notes of the proceedings of the HAZOP meetings. The team recorder is probably one of the most important roles in the HAZOP process. The recorder must be able to support the team dynamics and not slow down the process. 

Figure 12.8 illustrates how the HAZOP process is conducted on specific nodes of interest. In the HAZOP context, a node is a location on a process diagram (usually piping and instrumentation diagrams or P IDs) at which process parameters are investigated for deviations. Nodes are also points where the process parameters have identified design intent. Nodes are usually pipe sections or vessels. 

A HAZard and OPerability (HAZOP) study is an inductive technique, which is an extended Failure Mode, Effects and Criticality Assessment (FMECA). The HAZOP process is based on the principle that a team-approach to hazard analysis will identify mote problems than when individuals working separately combine results. 

The HAZOP process creates deviations from the process design intent by combining guidewords (no, more, less, etc.) with process parameters resulting in a possible deviation... 

To apply the HAZOP process for the study of a fishing vessel system, the conventional method... 

The HAZOP process can be time consuming and costly if it is not well prepared in advance and... 

Figure 3.4 Flowchart of HAZOP process applied to fishing vessels...

Generally a higher level than the HAZOPS process and results in a quicker study. 

---