Overview

Improper or insufficient maintenance can lead to serious personnel or process accidents. Occasionally, well-intended maintenance activities inadvertently introduce an unwanted situation into a carefully engineered plant. A lack of a maintenance program with proper inspections and tests can also result in accidents. This chapter will review both of these maintenance causes of accidents while emphasizing piping-related case histories.

Maintenance employees often work on equipment and piping that handles high volumes or high flow rates of hazardous materials. Maintenance mechanics' jobs often consist of opening up piping systems and vessels that previously contained hazardous chemicals and may still have an undetermined amount of hazardous chemical residues. It is logical to think these vital upkeep activities share a significant role in plant accidents. Trevor Kletz often stated during his Continuing Education lectures for the American Institute of Chemical Engineers that, in his industrial experience, the preparation for maintenance and the actual maintenance activity accounted for more chemical plant accidents than any other single cause.

In most plants, piping systems require plenty of maintenance, and piping changes occur frequently. Typically there is piping replacement (due to corrosion or to provide larger diameter piping for more flow rate), some rerouting, and other less glamorous activities to clear and clean piping. And then there is the periodic installation of blinds and the replacement or repair of block valves, control valves, and leaking fittings.

A high percentage of the incidents covered in this chapter involve piping maintenance problems, and this chapter concludes with case histories...