Process hazard review generally

A typical agenda for a Process Hazards Review generally follows these lines ... 

Many different factors need to be evaluated when determining which process hazard review methodology should be utilized. These include the complexity of the equipment or process, previous e q)erience of accidents or incidents and the potential consequences of an adverse event such as serious injury or community contamination. Other parameters include time available, cost, etc., since the time and complexity of the various analyses varies widely. In general, the what-if analysis is the simplest and least expensive. 

HAZOP reviews have been stated as arising from the chemical industry in Britain during the 1960 s. Imperial Chemical Industries, Ltd. (ICI) developed a standardized method of analyzing processing hazards based on the basic operation conditions and then changed individual parameters one at a time to see the subsequent consequences. This evolved into a standard practice within their company and soon found its way into the general chemical industry (although it was not universally or consistently applied). 

It is also prudent that the general results of a process hazard assessment technique are explained or are known to management prior to its occurrence, so that their expectations are consistent with those results. Management should fully realize that monetary commitment (manpower and financial expenditures) are required to initiate, perform and follow up the review. 

The bulk of process hazard analyses (PHA) in the petroleum and related industries will be either a HAZOP or a What-If review. Generally in the upstream sector, 60 - 80% of the safety reviews will be a What-If review, while in the downstream sector, 60 - 80% will be HAZOP reviews. 

The next example is of a Pre-Startup Review or a Process Hazards Audit held on a piece of purchased processing equipment, a Haake Rheocord Torque Rheometer and Laboratory Twin-screw Extruder. The organization responsible for this extruder has a standard checklist of eleven pages of items to be considered by the technical person or persons in charge of the equipment or process, before the review is held. Copies of the completed checklist are then sent to each committee member before the meeting for review. Generally, in a review of this type, the group will convene at the location of the equipment rather than in a conference room to go over the material provided. In this case, the committee consisted of ... 

The first step in the process is risk identification, which is accomplished by review of the proposal/study by suitably experienced experts using well-considered checklists. These must embrace all facets which may affect the project outcome, such as plant feedstock quality, process reliability, mechanical reliability, potential foundation problems, operational hazards, environmental impact, equipment costs, construction costing and labour, statutory requirements, contractual and legal problems peculiar to the country of construction, eventual decommissioning costs, and so on. Risks due to operational hazard are generally treated separately from commercial risk, and will be discussed in Chapter 12, but they are obviously an essential part of the overall process. 

Safety Review. The safety review was perhaps the very first hazard analysis procedure developed. The procedure begins by the preparation of a detailed safety review report. The purpose of this report is to provide the relevant safety information regarding the process or operation. This report is generally prepared by the process engineer. A typical outline for this report follows. 

It generally is recommended, and often required, that gas dcicciiuii systems be installed in a fail-safe manner. That is, if power is disconnected or otherwise interrupted, alarm and/or process equipment shutdown (or other corrective action) should occur. All specific systems should be carefully reviewed, however, to ensure that non-anticipated equipment shutdowns would not result in a more hazardous condition tlian the lack of shutdown of the equipment. If a more hazardous situation would occur with shutdown, only a warning should be provided. As an example, a more hazardous situation might occur if blowout preventers were automatically actuated during drilling operations upon detection of low levels of gas concentrations than if drilling personnel were only warned. 

Review background information obtained from the facility to develop a general understanding of process safety hazards, areas of process safety concern, chemicals and processes used, etc. Typical background information includes ... 

This section discusses how a runaway reaction occurs and lists some of the process deviations that can lead to such a runaway. Equipment for identifying potentially hazardous process steps is reviewed, and general principles for inherently safe process design are given. 

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