After the hot work was completed, the contractors left the site. During one of the routine operational

checks, the operator sees flames on the ground floor. In accordance with training, they instantly

operate a safety shower and use their radio to communicate the details to the shift manager. The

operator then asks the process control room operators to remotely activate the plant evacuation

alarm. The evacuation alarm sounds and the associated red lights flash.

The operator sees that the acetylene gas bottle hose has flames coming out from it at several points.

Flames are in contact with the middle of a pressurised process plant vessel, one of the few vessels

that contain a hazardous substance. The vessel is half full of a flammable liquid, and it has an

integral pressure relief valve.

In accordance with their training, the operator locates a dry powder extinguisher and tries to

extinguish the flames. The flames temporarily extinguish, and then reignite. The operator retreats

from the fires and decides to wait for the emergency rescue team.

All other workers on the plant immediately and calmly evacuate, and the operator helps to direct

people to the assembly point. The evacuees congregate at the signposted assembly point, to await a

roll call and permission to return to the plant. The return to the plant will only be authorised once the

$$all clear$$ is given by the shift manager, who acts as the incident controller.

The shift manager and emergency rescue team arrive. The team leader calmly assesses the

situation, walks over to the acetylene cylinder and closes the isolating valve. Within seconds the fires

are extinguished. The shift manager decides not to contact external emergency services. They also

instruct one of the rescue team to direct a fire hose onto the vessel to slowly cool it$.$

The subsequent investigation determined that the hoses supplied by the specialist contractor team

were old, and the rubber had cracked at three points, through which acetylene was escaping.

Task $4$: Successful application of the emergency plan

$4$ What aspects of the emergency plan worked well once the acetylene hose fire

was observed by the operator? $20$ points

Note: Your answer must be based on the scenario only.