Safety, Loss Prevention and HAZOP

Factors relating to the safety of a chemical plant have so far been ignored. This is mainly because it is impossible to discuss all the aspects of plant design initially in a set of notes. The designer will obviously design items of equipment, and perform other tasks in process design, in 

Property word Guide word Cause Consequence Action. 

It is important to identify not only what may happen (consequences) and why (causes), but also what should be done (actions) to prevent serious accidents. Examples of operability studies in particular situations are included in Coulson and Richardson, Volume 6 (1983 pp. 292-294, 296298). Modifications initiated in one section of the plant can have effects in other sections, it is therefore necessary to consider the effects of any changes that are made on the overall operation of the plant. The existence of recycle lines requires careful consideration in the study. A second operability study may need to be performed after all the actions have been incorporated into the design and included on the flowsheet. 

Note In student design projects, the aim is to produce a competent design and also to communicate to the supervisor what has been done. It is therefore essential to include a summary of the major findings obtained by performing the HAZOP study (this is usually only performed on one 

Safety check lists can provide a uselul guide for the main items to be considered during the process design stage. It must be remembered that no list is ever complete and other considerations and techniques should also be applied. Safety check lists can be found in Coulson and Richardson, Volume 6 (1983 pp. 301-303) IChemE Flowsheeting for Safety (1976) Wells (1980) and Balemans (1974). 

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