Abstract
Daily operations and equipment failures may require slight process changes which in many cases are carried out without any effect on safety. But sometimes unknown hazards are hidden beyond those slight changes.
Even if a company has a well implemented Management of Change protocol, the evaluation of every single process change may be difficult to assess in detail as a balance between time available and analysis depth has to be achieved, therefore assessment is made with information and knowledge available in the spot. In this sense, even if the evaluation is done, the knowledge available may lead to neglect hazards.
In this paper, an example of a slight process change is presented which lead to a runaway reaction and a drum burst. Hopefully no injures had to be blamed and only damages on the area where the drum burst had to be considered.
A solvent and a process reactant were mixed for a too long time inside a drum due to a pump failure leading to a different operation during the dosing of reactants into the reactor.
The change was evaluated according the MOC and available criteria by plant operator, shift leader and production chemist on duty, without identifying any significant hazard thus allowing the chance to be carried on.
Investigations later revealed that a hazardous exotherm reaction was present at temperatures close to ambient temperature between the reactant and the solvent.
This case is an example of an unknown by the operational workforce – known only by experts and the fact that experts may not be systematically involved in the assessment of slight process changes due to the time available to carry out operations.
Beside the analysis and explanation of the accident, the aim is to define measure to prevent similar incidents to take place; therefore lessons learned allow defining some recommendations related to MOC management which can be applied to any company helping to unhide hazards and make the knowledge available to people carrying out operations in the field.
