1.1.3 The causeSomeone modified the truck’s nitrogen padding system and constructed a manifold on the truck that allowed the nitrogen hose connection to be made without climbing the ladder on the truck’s tank 1. Engineers determined that a nitrogen valve was opened to the hose connected to the tank trailer manifold. The nitrogen gas never entered because there was a closed valve atop the tank. It seems the truck driver misunderstood the recent nitrogen supply piping modification; the open and closed positions on this oval handle ball valve. Investigators observed a device that appeared to be a combination safety relief valve and a vacuum breaker. The information on this chrome-topped instrument read, “Press 26,700 CFM @ 32.5 psig,” and “VAC Relief 1,750 @ 1 psig.” Despite the nameplate, the trailer was not equipped to deal with vacuum 18.104.22.168 Lesson LearntNONE.No investigator for the chemical plant tried to determine when the well-intentioned tubing manifold was installed. The truck was owned and operated by a transportation company. But it was obvious that the hardware on this little change was not explained to the driver. The driver just did not know how to determine if the oval handle valve was fully opened or closed. Good communications and training (if necessary) must always be part of a procedure involving changes (even simple changes, like this one).1.1. Safety Concepts and DefinitionsSome important safety concepts and definitions have been listed down. The clear meaning needs to be understood before implementation of safety measures.1.2.1 DefinitionsSafe Operation:The name is not as obvious as it sounds. Generally, it is associated if there is no risk involved, the operation is assumed as safe.”Safe Operation consist of essential codes of practice for various hazardous activities & operations. It detail the system of work to be undertaken in the interests of safety, quality and efficiency. It defines the safe method of operation for all hazardous activities.” 2Risk:The IEC (IEC 61508, 2000) 3, defines”risk as a combination of the probability of an occurrence of harm and the severity of this harm”Harm:”Harm is defined as physical injury or damage to the health of people either directly, or indirectly as a result of damage to property or to the environment.”Accidents:”Unexpected sudden sequences of events, with undesired outcomes inflicting damage to people, property and/or the environment.”Active failures:Failures made by those in the operational process, that result into deviationsDouble loop learning:A way of regulating in a control process by questioning the organizational values and norms, to correct the deviations and to reach the desired outcome set by the organizational values and norms. Incidents:The combined set of accidents and near misses. Intervention:An element in the control process, situated behind the judgement element. Its purpose is to intervene in the input, resources or output of a transformation according to the organizational values and norms.Near miss:A sequence of events which is prevented from developing further into undesired outcomes inflicting damage to people, property and/or the environment.Observation:An element in the control process, situated before the judgement element. Its purpose is to monitor if the transformation and that the output of the transformation are according to the organizational values and norms.1.2.1 Safety ConceptsDetermination of risk 4:It can be made by questioning three factors; event, likelihood and consequences:What can go wrong? (event)What is the probability of occurrence? (likelihood)What are the consequences? (consequences) Incidents, Accidents and Near Miss concept 4:
Like risk, accidents and incidents are context specific concepts, which are subjective, and strongly depend on people’s perceptions. The difference between incidents and accidents is that accidents are the outcome of an incident or series of incidents having high consequences. Therefore, incidents can develop into an accident according to van der Schaaf 5, who also recognizes an intermediate state as a near miss. He defines a near miss as a situation in which an ongoing sequence of events is prevented from developing further into an event with .high. consequences. He combined the concepts of near miss, incident, and accident, as depicted in Figure 3, van der Schaaf 6. Incidents are in this respect the combination of near misses and accidents. Figure 3 shows that an organization may prevent dangerous situations from developing into an accident by various measures and tools (defenses). If these defenses are not adequate, the situation develops into an event with low perceived consequences (incident). From here on it is often the operator who may adequately recover the situation, which means the incident, becomes a near miss. However, if no adequate recovery takes place, the incident will be able to develop into an event with high perceived consequences (accident).Is it possible to identify early signs of accidents in an operational process?
The assumption of the research is that early signs are present which can prevent a small miss-happening in becoming a big disaster. Considering only that the early signs are enough to prevent any accident is quite unlikely. But the signs can be used to make a safety management protocol. It is more important to devise a pro-active measure to discover the underlying factors, causing the possible accidents. Subsequently companies can direct resources at these identified causal factors and possible accidents can actually be prevented. The next research question is therefore;
Is it possible to identify the casual factors which can explain accidents?
The research will require a understanding of accidents and the role of early signs in identification of these factors. The third research question can be formulated as;
Why do accidents still occur despite all the safety measures and how can the pro-active identification help in safety management?
This is the most important question which needs to be answered. It also deals with development of safety models and protocols. Eventually, it will let the operators predict when an accident would happen.
Answering these questions will help theory and practice in where to look for signs and derive causal factors for accidents, and show why accidents still occur in spite of all measures currently taken. It is inevitable that some accidents will occur, because not all accidents can be foreseen and prevented. The next Chapter will describe the underlying research process and will present the research methodology.
1.1. Research Scope
The ultimate aim of this research is make a multi-layered safety plan. The proposal is also to make a theoretical model which can always be referred or recommended while making the safety procedures of the plant. Literature shows existence of already such kind of models but most of them focus on “what to do when somethings goes wrong?”. The idea in this model is to pro-actively identify the potential hazards and include them in regular maintenance plan. The early signs identification must be a part of operator training and to be reviewed and improved on a regular basis. The boundaries of the research work are:
· No disaster/hazard which is due to natural calamity will be studied.
· The cases to be listed will be more general, that could be applied as standard procedure. Specific requirements of a certain operation not dealt.
· No limitation on geographical location of the chemical plant.
· The hazard studied will be of near past.
Concluding, the research will demonstrate an active list of accident precursors and ways to contain them. This will be supported with theoretical models and lessons from past miss-happenings. Moreover, recommendations in day-to-day tasks of operators to follow.