Investigating incidents initiating

The employer investigates incidents that result in, or could result in, a catastrophic release of highly hazardous chemicals. An incident investigation is initiated as soon as possible, but before 48 hours following the incident. An incident investigation team is established to consist of one or more experts in the process involved, and accident investigation. The report prepared at the conclusion of the investigation includes at a minimum ... 

Maintain a capability to promptly investigate incidents and events in order to initiate and support corrective or preventive action... 

After the incident, an investigation team determined that the first operator had not added the initiator when required earlier in the process. When the relief operator added the initiator, the entire monomer mass was in the reactor and the reaction was too energetic for the cooling system to handle. Errors by both operators contributed to the runaway. Both operators were performing many tasks. The initiator should have been added much earlier in the process when much smaller quantities of monomer were present. There was also no procedure to require supervision review if residual monomers were detected. The lesson learned was that operators need thorough training and need to be made aware of significant hazardous scenarios that could develop. 

The initial incident report is very important. This document captures the initiator s firsthand knowledge of what occurred in the moments after the specific event. Example 5-2, Sample Toller Initial Incident Report, is an example of the data that should be documented as soon as possible. Note that it should be modified using the company s management system procedure and incident investigation procedure, which should describe the type of data needed, and level of detail desired. 

In this case study, one of the strongest blast-generating BLEVEs to occur in the Mexico City incident (Section 2.4.3, Pietersen 1985), will be investigated. This BLEVE occurred a few minutes after the initial vapor cloud explosion and probably involved two 1600-m spheres. The spheres were probably 50% full at the time of the accident. 

However, MORT does not aid in the representation of the accident sequence which must first be determined before the method can be effectively used. Although MORT provides a comprehensive set of factors which may be considered when investigating an incident, it can easily turn an investigation into a safety program review as no guidance is provided on the initial investigative process. 

The case study has documented the investigation and root cause analysis process applied to the hydrocarbon explosion that initiated the Piper Alpha incident. The case study serves to illustrate the use of the STEP technique, which provides a clear graphical representation of the agents and events involved in the incident process. The case study also demonstrates the identification of the critical events in the sequence which significantly influenced the outcome of the incident. Finally the root causes of these critical events were determined. This allows the analyst to evaluate why they occurred and indicated areas to be addressed in developing effechve error reduchon strategies. 

The regulation states An incident investigation shall be initiated as promptly as possible, but not later than 48 hours following the incident. In part, the reason for this quick response to an incident is to assure that all pertinent evidence and facts can be preserved to facilitate the investigation. 

Shumaker SA, Legault C, Rapp SR, Thai L, Wallace RB, Ockene JK, et al. and WHIMS Investigators (2003) Estrogen plus progestin and the incidence of dementia and mild cognitive impairment in postmenopausal women the Women s Health Initiative Memory Study a randomized controlled trial. J Am Med Assoc 289 2651-2662... 

Initially, the literature is searched for relevant data on the substance (physical-chemical properties, thermodynamics, incidents, case studies, and so forth). If insufficient data are available, the usual case, a systematic investigation procedure comprising three main subjects must be initiated for the material in question. 

The Chemical Incidents Report Center (CIRC) is an incident database initiated by the U.S. Chemical Safety and Hazard Investigation Board. An online search of this database (www.chemsafety.gov/circ), as well as a more general web search, may be a good starting point for a literature survey. 

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