Maintenance shift system

Settlement/storage areas for effluent need to be sized not just for average flow but also for peak periods. Where production is based on a shift system, peak flows created during holiday periods (shutdown, major maintenance, etc.) should be considered. 

Started. Since pump A and its associated pipework was off-line, the supervisor took the opportunity to carry out scheduled maintenance on the pressure relief valve (PRV) downstream of pump A. The valve had been malfunctioning, and although the work was not scheduled to be done for some weeks, the specialist contractor team who maintain the PRVs had a team available to carry out the work immediately. The supervisor therefore now had two teams working on the pump A systems the shift maintenance team working on the pump itself, and a two-man contractor team working on the PRV and its associated pipework. The PRV for pump A is not located immediately adjacent to the pump, and is above floor level, close to a number of other pipe runs. The following description represents a hypothetical sequence of events based on the inquiry findings, but embellished for the purposes of the case study. 

The root causes for this critical event both concern the operations department and the service department who ran the contractor maintenance team. The operations department (i.e., the day shift operations supervisor) failed to provide adequate supervision and instructions to the contractor team. Explanations of the nature of the permit-to-work systems (i.e., the need to report back at end of shift) should have been given, and the possibility and implications of work not being completed before the end of the shift should have been considered by both parties. 

On the night of the accident, operators heard a screeching noise from the relief valve on one of the tanks. Unfortunately, the closed blowdown system had been taken out of service for maintenance. It was later established that while operators were on their shift change or on a break, someone disconnected a pressure gauge from the cover plate on one of the tanks and attached a water hose. A quantity of water estimated between 450 and 900 kg entered the tank and caused a severe upset and release of MIC vapor. With no means of notifying the public and evacuating the community, thousands were exposed to the vapor cloud, resulting in the deaths and injuries. 

The mechanism of development of tolerance and physical dependence is poorly understood, but persistent activation of preceptors such as occurs with the treatment of severe chronic pain appears to play a primary role in its induction and maintenance. Current concepts have shifted away from tolerance being driven by a simple up-regulation of the cyclic adenosine monophosphate (cAMP) system or a down-regulation and recycling of preceptors from the cell surface to cryptic... 

If an instrument or instrument system malfunctions, the operator tries to correct the problem. If an alarm, flow- or temperature-measuring instrument or shutdown system malfunctions, the operator s first response should be an attempt to restore it to service. It may be a plugged impulse line, inadvertent flow shut off to an analyzer, etc. If the Instrument System is a Class 1 or 2, immediately go to Step 2. If the alarm is a Class J. the Lead Operator (or Shift Foreman) should be consulted and follow established procedures and his knowledge of the unit and the specifics of the situation to determine the temporary steps required. At the minimum, a note in the maintenance logbook must be made to initiate repairs. Stop Here for Class 3 Alarms. 

The availability of capital resources is equally important. As mentioned, the current health care system— including the emergency, acute, and chronic care components—are all operating at maximal capacity. However, EMS vehicles, ED and hospital beds, and operating rooms will be needed in differing levels based on the incident (Auf der Heide, 2006 Pesik et al., 2001). For the EMS system, planners must know and address mutual aid issues. In upstate New York, Rural Metro Medical Services provides EMS in many cities and has a plan to shift resources between cities in event of crisis. Thus, additional ambulances, communications equipment, and maintenance facilities can be deployed throughout the region. In other areas, mutual aid compacts must be in place to allow for the immediate recruitment of as many additional EMS units as are needed (Auf der Heide, 2006). 

The staff requirements shown below apply to the Purifax process, macerator, pumps, and chlorination system. Dewatering or thickening operation and maintenance are not included. The labor requirements of a package chlorine treatment unit are listed below (a) Operation = 2 h/shift/unit and (b) maintenance = 3 h/shift/unit. 

Traditionally, flooded lead-acid batteries have been the technology of choice for use in RAPS systems. During the last 10 years, however, there has been a considerable shift towards VRLA batteries. The main driver for this change is the low maintenance requirement of the latter technology. This and other important issues are discussed in the following sections. 

For maintenance small valves are easier and much cheaper to replace. However, the main advantage is that all ports can be shifted independently from each other. SMB plants are very often designed with a suction line of the recycling pump, which is much longer than the other lines between the columns. In the case of asynchronous shifting, it is necessary to compensate the unequal distribution of the dead volume. In the case of the Varicol process, an asynchronous multicolumn continuous system derived from SMB (Section 5.2.5.1) individual switching of the inlet and outlet lines is obligatory. 

---