Operations teams

If a toller has a contract to perform the same toll repeatedly, but on an infrequent basis, training should not be overlooked in preparation for restarting the repetitive toll. It is a good practice to provide refresher-training sessions to assure that the personnel have received current training. One company has picked a six-month period between campaigns as the indicator that the operations team needs refresher training. 

The operating team as a whole had been aware of the well-known hazards of water hammer in steam mains. 

The investigation showed that at the time the operating team members were busy at the main plant, which they operated. A deputy foreman had been left in charge of changing the relief valve. He wanted to get it done while a crane was available. 

A similar incident occurred on another furnace when the heat transfer oil froze inside the furnace during unusually cold weather. Outside the furnace, the lines were steam-traced. The operating team decided to thaw the frozen oil by lighting one of the burners... 

After the furnace had been allowed to cool, the operating team, not realizing the extent of the damage, restarted the flow of feed water. They stopped it when they saw water running out of the firebox. It is fortunate they did not start the water flow earlier, or it would have caused explosive vaporization of the water [17]. As stated in Section 9.2.2 (e), equipment that has been taken outside its design or test range should not be used again until it has been examined. 

From the traditional HF/E perspective, error is seen as a consequence of a mismatch between the demands of a task and the physical and mental capabilities of an individual or an operating team. An extended version of this perspective was described in Chapter 1, Section 1.7. The basic approach of HF/E is to reduce the likelihood of error by the application of design principles and standards to match human capabilities and task demands. These encompass the physical environment (e.g., heat, lighting, vibration), and the design of the workplace together with display and control elements of the human-machine interface. Examples of the approach are given in Wilson and Corlett (1990) and Salvendy (1987). 

In the CPI, the most extensively studied human-machine interface is in the central control room in automated plants where plant information is displayed on visual display units (VDUs) and appropriate control actions are made by the operating team. In the case of a highly automated plant, the primary role of the human is to respond to unexpected contingencies such as plant states that have not been anticipated by the designers of the automatic... 

The dotted lines in the diagram indicate the various feedback paths that exist to enable the individual to identify if a particular stage of the processing chain was executed correctly. Thus, if the operating team had planned a strategy to handle a complex plant problem, they would eventually obtain feedback with regard to whether or not the plan was successful. Similar feedback loops exist at the rule and skill-based levels, and indicate opportunities for error correction. The application of the stepladder model to a process industry example is given in Appendix 2A at the end of this chapter. 

If the pattern does not fit into an immediately identifiable pattern, the process worker may then consciously apply more explicit "if-then" rules to link the various symptoms with likely causes. Three alternative outcomes are possible from this process. If the diagnosis and the required actions are very closely linked (because this situation arises frequently) then a branch to the Execute Actions box will occur. If the required action is less obvious, then the branch to the Select/Formulate Actions box will be likely, where specific action rules of the form "if situation is X then do Y" will be applied. A third possibility is that the operating team are unable or imwilling to respond immediately to the situation because they are uncertain about its implications for safety and/or production. They will then move to the Implications of plant state box. 

At this stage the implications of the situation will be explored, using the operating team s general fxmctional knowledge of the process. This explicit... 

It is not possible to predict all the potential situations which the process worker will have to deal with. Unfamiliar situations sometimes arise whose recovery is entirely dependent upon the operating team. When this is the case, the likelihood of success will depend upon the problem solving skills of the process workers. These skills can be trained in refresher training exercises... 

In another incident, a maintenance foreman was asked to look at a faulty cooling water pump. He decided that, to prevent damage to the machine, it was essential to reduce its speed immediately. He did so, but did not tell any of the operating team immediately. The cooling water rate fell, the process was upset and a leak developed in a cooler. 

This technique sets out to collect data about near-incidents or critical events that have been experienced by the operating team but that are unlikely to be documented. The basic premise of the technique is that events that could have led to serious consequences would tend to be remembered by the workers. Through individual or group interviews, significant events are recalled which are then analyzed in order to generate useful information about the difficulties involved in the performance of a task, the adequacy of the operating procedures, any problems with the equipment or control panel design and so on. The technique can be used in three areas ... 

Operator action event trees are treelike diagrams that represent the sequence of various decisions and actions that the operating team is expected to perform when confronted with a particular process event. Any omissions of such... 

In spatial OSDs the flow of events and symbols is overlaid on a map of all items of equipment with which the operator interacts during the task. The map itself does not have to be very accurate, provided that the general geographical relationships among items of equipment are shown. The spatial OSD thus provides a graphical description of the perceptual-motor load a particular task imposes on the performance of the worker. For multiperson tasks, the operational sequences for several workers can be coded in different colors and superimposed onto the same equipment map. This can generate useful information for the distribution of tasks to different members of the operating team. 

Typically, the first phase of a comprehensive accident investigation process will involve describing the way in which the hardware, the chemical process, individual operators and operating teams are involved in the accident process. This is the domain of the structural analysis techniques and the technical analysis of the chemical process which gave rise to the accident. Analyses of human error will primarily address the interactions between hardware systems and individuals or operating teams (the first two layers... 

These may give rise to lack of clarity with regard to who is responsible within an operating team. 

Preparation of Equipment for Maintenance The essential feature of this procedure is a permit-to-work system The operating team members prepare the equipment and write down on the permit the work to be done, the preparation carried out, the remaining hazards, and the precautions necessary. The permit is then accepted by the person or group who will carry out the work and is returned when the work is complete. The permit system will not make maintenance 100 percent safe, but it reduces the chance that hazards will be overlooked, lists ways of controlling them, and informs those doing the job what precautions they should take. The... 

Army Technical Escort Unit 52nd Explosives Ordnance Disposal Unit and other selected Department of Defense (DOD) units DOE Joint Technical Operations Team, DOE Nuclear-Radiological Advisory Team, DOE Nuclear Emergency Search Team, DOE Lincoln Gold Emergency Team. 

Obviously, a multidisciplined safety review committee may have detected the problems of the ill-advised use of a combination vent/overflow line, but this type of collapse is viewed as somewhat of an oddity. Several variations of this type of collapse have been reported on low-pressure and atmospheric tanks. Another incident occurred when a company requested the operating team to fill a tank as high as possible for storage needs, so they ignored the high-level alarm. After the tank level reached the overflow, the liquid started pouring out of the overflow faster than it was being pumped in and the tank collapsed. [4]... 

The operations team in this area of the plant was convinced that if changes were to be made in any equipment, reactants, intermediates, catalyst, or any operating conditions of the process were modified, the system would be first reviewed by a committee. In the operations teams mind, this was just a waste water line. As is apparent in Figure 2—18, the danger of just blocking the water drain lines at any time the system is in operation would cause physical explosion. 

Talented supervisors often need to make improvements, but with their zeal to improve they may fail to see the need for all of the fanfare of a committee review for a small change in a utility system. In a previous example, the operating team made a small change in just a waste water line that yielded damages of over a half-million dollars. 

It was the practice to neutralize slight acidity in such solvents in a pressure vessel (called a neutralizer) that was filled with solid caustic soda flakes or beads. Such treatment was a common method to improve tainted inventories of solvent intermediates and products. The operating team was pleased to secure the equipment and caustic soda to improve this product. 

Just before a plant startup, the operations team wondered if the piping upstream of a flammable gas compressor may not have been cleaned sufficiently to prevent dirt from entering the precision machinery. Concerned employees had a temporary filter installed in the suction line. The operations team was correct there was a sufficient amount of foreign material in the upstream piping to plug up the filter. [8]... 

At the time of the incident, the operating team was preparing to simulate operations by circulating water in the system. Shortly after midnight, operators noticed water coming from the reabsorber vent. Pre-op engineers concluded that water had flooded both the... 

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