Piper Alpha incident

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. 

Smoke is a by-product of most fires caused by the incomplete oxidation of the fuel supply during the chemical process of combustion. It accounts for a large majority of fatalities of from fire incidents at both onshore and offshore petroleum facilities. In the Piper Alpha incident of 1988, probably the worst petroleum industry offshore life loss incident, the majority of deaths were not from bums, drowning or explosion impacts but from smoke and gas inhalation. The report on the incident concluded that, of the bodies recovered from the incident, 83% were as a result of inhalation of smoke and gas. Most of these victims were assembled in the accommodation awaiting evacuation directions or as they may have thought - a possible rescue. 

Dr Toity Barrell- former Chief Executive of North Sea Safety provided a memorable quote on sameness of incidents within the video Spiral to Disaster . The video captures maity aspects of the July 1988 Piper Alpha Tragedy. The July 1988 Piper Alpha incident resulted in 167 fatalities on a rig in the North Sea. Actors realistically portrayed... 

In the United States (principally the Gulf of Mexico) the response to the Piper Alpha incident was equally vigorous, but followed a different path. The American... 

Companies operating in the Gulf of Mexico had an equally forceful response to the Piper Alpha incident, but their approach was strategically different. There had not been a Safety Case system prior to Piper Alpha instead there were thousands of platforms (many of them simple, small, and similar to one another). Rather than preparing individual safety cases for each of these near-identical... 

Virtually all of the elements of Process Safety/SEMS played a role in the Piper Alpha incident, so profound was its nature. Three elements in particular are identified in Table 2.6. 

The Piper Alpha incident is described in Chapter 2. Piper Alpha, like most offshore production platforms, has a very limited on-board inventory of oil and gas. However the platform was also a hub—other platforms were pumping to it. Had they stopped pumping as soon as the first explosion had occurred, the loss of life would have been considerably less than the final toll, and it is likely that the platform would have been saved. 

Smoke is a by-product of most fires caused by the incomplete oxidation of the fuel supply during the chemical process of combustion. It accounts for a large majority of fatalities from fire incidents at both onshore and offshore petroleum facilities. In the Piper Alpha incident of 1988, probably the worst petroleum... 

A subsequent investigation into the disaster was conducted by the United Kingdom government that identified a number of factors that, directly or indirectly, contributed to the Piper Alpha incident s severity. Two of these factors were as follows [13-15] ... 

If two or more jobs are being carried out on the same piece of equipment or in the same area, the chance for confusion as to which permit applies to which controls arises. Failure to control multiple permits was a major factor in the Piper Alpha incident—two permits were open on one compressor. When the first job was finished, its permit was closed and the compressor was started, even though the machine had a missing blind flange associated with the second job. 

Following the Piper Alpha incident in the North Sea in 1988, and the recommendations of an inquiry held by Lord Cullen, an offehore hydrocarbon release database has been set up in the UK by the Offshore Safety Division of the Health and Safety Executive (HSE). Reports are mandatory and, as a result, this database represents an accurate picture. Most offshore installations include gas turbines and the database thus records incidents relating to them. Data from 5.5 years of operation has been analyzed, showing that there were 85 incidents within this period associated with fuel at gas turbines in general. Of these, 52 were ignitions and 4 resulted in explosions. One incident in particular was classified as of major potential. 

This case study concerns the events leading up to the hydrocarbon explosion which was the starting point for the Piper Alpha offshore disaster. It describes the investigation of the incident using the sequentially timed events plotting (STEP) technique. Based on the STEP work sheet developed, the critical events involved in the incident are identified and analyzed in order to identify their root causes. 

An initial explosion occurred on the production deck of the Piper Alpha Offshore Platform in the North Sea at about 1 00 PM on July 6,1988. The incident escalated into a tragedy that cost the lives of 165 of the 225 persons on the platform. Two additional fatalities occurred on a rescue boat. The Piper Alpha Platform was totally devastated. 

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. 

The ESD system is distinguished from other facility safety systems in that it responds to a hazard situation which may affect the overall safety of the entire facility. It is therefore considered one of the prime safety systems that can be provided for any facility. Without an ESD system, an incident at a hydrocarbon facility may be provided with "unlimited" fuel supplies that can destroy the entire facility. Such situations are amply demonstrated by wellhead blowouts that can be fed from underground reservoirs and destruction of pipeline connections at offshore installations affecting the availability of further isolation means, eg., "Piper Alpha". 

Isolation - It has been shown that the addition of isolation valves at periodic intervals is not as cost effective as prevention measures such as thickness inspections or tests. However all pipelines should be provided with a means for emergency isolation at it entry or exit from a facility. Offshore facilities may be particularly vulnerable to pipeline incidents as the Piper Alpha disaster has shown. In that accident a contributing factor to the destruction was the backfeed of the contents of the gas pipeline to platform once the topside isolation valve or piping lost its integrity. Further isolation means (i.e., a subsea isolation valve SSIV) were not available. 

The first safety cases prepared for the process industries were those developed for North Sea offshore oil and gas operations following the Piper Alpha disaster that occurred in the year 1988. The Cullen report (Cullen, 1990) that was written following that accident was highly critical of offshore operating practices and recommended that a safety case approach be implemented. The Seveso incident that occurred in Italy further prompted the increased use of safety cases. Since that time the use of safety cases has spread to other industries (such as mining and railway operations) and to other nations, primarily in Europe and Australasia. (It is notable that the safety case regime approach has not been taken up for offshore oil and gas operations in the Gulf of Mexico—instead a more prescriptive approach based on industry consensus standards is used.)... 

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. 

There is sufficient evidence from well-known historical events to indicate that safety culture (Piper Alpha), human error (Kegworth) and violations (Herald of Free Enterprise) all play major roles in the occurrence of incidents. Coupled with the increasing importance being afforded to the human factors causes of incidents, organisations have a very convincing case for the development of an integrated suite of tools for incident investigators. 

It is very important that drills are carried out frequently. Many incidents— most notably Piper Alpha— were made much worse because the people involved did not know what to do. 

Procedural problems are frequently cited as the cause of major accidents, contributing to some of the world s worst incidents, such as Bhopal. Piper Alpha and Clapham Junction. In the major hazard industries, fit-for-purpose procedures are essential to minimise errors, and to protect against loss of operating knowledge (eg when experienced personnel leave). 

In addition to reducing performance efficiency, the employment of operators with substandard competence levels within safety-critical systems can have grave consequences. For example, a review of major accidents in the hazardous industries indicated that a lack of operator skills and/or knowledge led to the errors that contributed to the accidents analyzed (Wright et al., 2003). Wright et al. (2003) also referred to the Southall rail crash, the Piper Alpha oil rig disaster, the Longford Esso Gas plant explosion, and the Hickson Welch fire as examples of incidents where staff incompetence played a part and where staff competency levels were not sufficiently tested by the organizations involved. 

The supervision of process control teams is a key factor in ensuring plant efficiency and safety. Previous research in various domains has identified the key role that effective supervision plays in the efficiency of subordinates work performance. Further, various studies have identified poor or inadequate supervision as a key contributory factor in accidents and incidents within complex sociotechnical systems (e.g., BOMEL Consortium, 2003 Brazier, Gait, and Waite, 2004). For example. Brazier et al. (2004) highlighted the Texaco oil refinery, Hickson Welch, Nobel, and Piper Alpha explosions as examples of accidents in which inadequate supervision was evident. 

The importance of a safety culture cannot be understated. Safety culture has been identified as a contributory factor in many catastrophic incidents occurring within the hazardous industries in recent times, including the Ladbroke Grove and Southall rail crashes, Texas BP refinery explosion, the Challenger and Columbia space shuttle disasters, and the Piper Alpha oil platform disaster (Hendershot, 2007). 

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