Hazardous Materials Associated with Plant Equipment

Figure 3-16 Hazardous Materials Associated with Plant Equipment...

When synthesizing a fiowsheet, the designer should consider carefully the problems associated with operation under extreme conditions. Attenuation will result in a safer plant, providing the attenuation does not increase the inventory of hazardous materials. If the inventory does not increase, then attenuation not only will make the process safer but also will make it cheaper, since cheaper materials of construction and thinner vessel walls can be used and it is not necessary to add on so much protective equipment. 

Many accidents occur because the operator or maintenance person does not understand the hazards involved or has not been instructed on the precautions to be taken. The policy document should identify the main hazards within the company with advice on which rules must be obeyed while carrying out a hazardous task. General rules should also be included to cover items such as untidy work areas, replacement of guards, the use of protective cloth-ing/equipment where appropriate, safe working practices in handling goods and materials, etc. It is essential that on the introduction of new products, processes, operations or plant and equipment that any hazards associated with these are brought to the attention of all concerned. 

The hazards associated with operations that involve more than one group can be reduced by the use of a permit system. O Driscoll has described the permit systems used in chemical operations many of these (hot work tank entry line breaking disposal operations excavations operation of material handling equipment and vehicles sprinkler-valve closing permit) are of interest in low-temperature plants. They are designed to permit the safe conduct of maintenance and repair functions. The use of written permits with copies to all groups concerned tends to increase the safety of potentially hazardous operations. Also, with use of written instructions, there is less chance for a misunderstanding. 

This chapter considers the nature and mitigation of the hazards associated with the movement and handling of materials. Later chapters will deal with specific equipment and plant procedures. 

A problem associated especially with multipurpose plants is the possible entry into an operating system of emical materials that are extraneous to the process in operation. For example, a solvent or raw material may be awaiting transfer to later use in another process in the same equipment. If incompatible with any of the materials used or produced in the process on line, the reserved solvent/raw material is a potential hazard unless positive steps are taken to exclude it from the ongoing process. Accidental intermingling is a two-way hazard. It is equally possible that a substance can leak from the process into the extraneous solvent/raw material. Inadvertent mixing can also cause difficulties in maintaining product quality and can present extra hazards to customers. 

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