Flixborough incident

In each case, two different methods were used in arriving at estimates the HSE TNT-equivalency method and the multienergy method. The results, in the form of side-on blast peak overpressures for various distances from blast centers, are listed in Table 7.10. In addition, some peak overpressures estimated by Sadee et al. (1976/ 1977) from Flixborough-incident damage patterns are included. The photographs in Figures 7.6a and 7.6b illustrate the practical effects of such overpressures. 

Blast overpressures calculated by the TNT-equivalency method are in reasonable agreement with the overpressures deduced from observed damage (Sadee et al. 1976/1977). This is to be expected, because the Flixborough incident is one of the major vapor cloud explosion incidents on which the TNT-equivalency value of... 

Ever since the inception of the petroleum industry the level of fires, explosions and environmental pollution that have precipitated from it, has generally paralleled its growth. As the industry has grown so has the magnitude of its accidental events. Relatively recent events such as the Flixborough incident (1974), Occidental s Piper Alpha disaster (1988), and Exxon s Valdez oil spill (1989) have all amply demonstrated the extreme financial impact these accidents can produce. 

PSSR (conducted before the modifications are commissioned) is also a part of the MOC procedure. Any new items identified during the PSSR may require further rounds of review and approvals by the reviewers. Completed MOC is an important part of process safety management it needs to be filed in the facility s process safety and project files, and stored for the lifetime of plant operations. These forms are required for future MOC audit and also are useful during future PHA studies. CCPS (1995) and CCPS (2007) presented MOC process and useful check lists. Note that a proper MOC procedure could have avoided the Flixborough incident outlined in Section 3.2 (CCPS, 2007). 

After the Flixborough incident in 1974 the HSE appointed a committee of experts, the Advisory Committee on Major Hazards, to consider the health and safety problems posed by major chemical sites and to make recommendations. This they did in three reports which identified a need for three basic elements of control ... 

Table 2.4 shows the elements of SEMP/SEMS that are of particular relevance to the Flixborough incident. 

HSE method) was based. Therefore, a TNT equivalency of 3% is a reasonable measure of expression of the explosive power of a vapor cloud under conditions similar to those at Flixborough. Such conditions may be considered typical major incident conditions. 

Robert M. Bethea, Process Safety Management with Case Histories Flixborough, Pasadena, and Other Incidents (New York American Institute of Chemical Engineers, 1994). 

The use of industrial chemicals with less explosive potential makes the process more intrinsically safe. Most dangerous explosions come from large clouds of flammable material which find an ignition source. Flixborough (Lees, 1996) is an example of the destruction caused by such an incident. 

Some of the most tragic and well-remembered accidents also had a start with a mini-modification made with a hose connection. The Bhopal Tragedy, the Three-Mile Island Incident, and the Flixborough Disaster were initiated by the improper use of hoses. 

A number of incidents in the past occurred because a change made to a covered process was not adequately reviewed for unintended consequences. The case in Flixborough is an example. The element that governs this is Management of Change [29 CFR... 

The Flixborough nylon plant accident in the UK (1974) was caused by an open-air explosion of a flammable gas released into the air. It killed the 28 plant employees present and caused extensive property damage in the surrounding area. The failure to perform a full technical assessment of a modification was given as the main cause of the event. The Seveso pesticide plant accident in Italy (1976) is well known for the dangerous release of dioxin due to poor plant safety features and to the underestimation of the possibility of a runaway reaction. The Bhopal incident in India (1984), at another pesticide plant, killed an estimated 4000 (although the total number is still unknown). This disaster was attributed to too large an inventory of toxic substances and to very poor staff attention to the operability of safety features. 

You can also find video clips of earlier major incidents including Philhps 66 Pasadena Texas (1989) Piper Alpha Catastrophe (1988) and Flixborough Disaster (1976). No doubt there are many others. 

Other disasters at chemical plants followed in 1976 at Seveso (Italy) there was a dioxin escape which polluted over 4000 acres of farmland, killed 100 000 grazing animals and led to the evacuation of 1000 people. Later (1984) in India a release of 40 tonnes of methyl isocyanate from a batch operation at Bhopal resulted in 40 000 deaths and 100 000 injuries. Incidents such as these would have either been avoided or extensively mitigated had the processes been intensified. In the Flixborough case, a very much smaller vapour cloud would probably have been incapable of developing the shock wave which proved to be so damaging. A continuous intensified version of the Bhopal reactor may still have caused fatalities, had the contents been released, but there would have been very many less than actually CKCurred. 

PICTURE 4.1 The Flixborough explosion. (From American Institute of Chemical Engineers, Process Safety Management with Case Studies Flixborough, Pasadena and Other Incidents, American Institute of Chemical Engineers, New York, 1994. Copyright 1994 by the American Institute of Chemical Engineers reprodueed by permission of Center for Chemical Process Safety of AIChE.)... 

VCE models have been applied for incident analysis [e.g., Sadee ct al. (1977) for the Flixborough explosion] and in risk analysis predictions (Rijnmond Public Authority, 1982). A flash fire model has been developed for risk analysis purposes by Eisenberg ct al. (1975). 

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