Failed Controller causes Incident
During a polymerization reaction (poly acrylates), a runaway reaction occurred and the vessle pressurized and relieved via the emergency relief system. Four tones of material were released to the roof, and some blown off-site. No one was injured.
It was found that a feed controller had failed, and added three toms of material in 45 minutes rather than 3 hours. As the plant was old there were no catch tanks for any release. The temperature alarms which were once in place had been removed as the plant was now "multi-purpose".