Once shutdown planning is well underway, the process of shutdown scheduling begins. During the planning and scheduling phases of a shutdown, there should be corresponding efforts in procurement, engineering, maintenance, operations, quality assurance, HSE & security, and administration in support of the work to be done before, during, and after the shutdown. To ensure these shutdown planning activities are tracked and completed, they should be included on the master execution schedule.
Process Technical Services has qualified and experienced personnel that can assist in developing the shutdown plans and shutdown schedule and the shutdown supporting activities in all participating areas.
Shutdown planning is used as input for shutdown scheduling. When shutdown scheduling starts, the units that will be shutdown are known, their shutdown duration is specified
the number of workers available and the number required for the shutdown. Since shutdown planning is an iterative process, performed by different people, the information for the scheduling phase could change. Therefore the shutdown schedule should be periodically updated, which makes the interaction between planning and scheduling iterative as well.
Scheduling the shutdown maintenance activities can be done before the scheduling of production, or along with the scheduling of production. In the first case, maintenance periods are already known and fixed at the time when equipment must be shutdown because of legal, manpower, shop fabrication limitations, or other constraints.
In the case of large single-line process units all units in the line will usually be shut down at nearly the same time. The ability to sequence the shutdown of large single-line units is determined primarily by intermediate storage capacity. Occasionally, product can be purchased from a competitor to sustain customers until the units are returned to service.
In a refinery the flow of components between units is scheduled separately from the shutdown. Usually the maintenance department schedules the shutdown and the production department schedules production. If the shutdown schedule were to be developed independently of the production schedule, then no consideration would be given to the capability of the production department to store components and to buy or sell them. Since a refinery consists of several complex processes, cooperation and coordination between the maintenance and production departments will produce a better overall schedule. This results in better efficiency during the shutdown period.
Shutdown scheduling does not end with the shutdown of the process for maintenance work. Beginning with the first day of the shutdown, the maintenance work should be monitored closely and changes in both the plans and the schedule should be kept current with events in the field. A change in the plans can arise because of hidden problems that were not discovered until after the process was shut down and equipment opened for inspection. Changes in plans require corresponding changes in shutdown scheduling.
Changes in plans can develop in the event that critical resources are not available as previously assumed. If the needed manpower is not available, then a schedule change is required. In large scale shutdowns, early changes in the plans and schedule can ripple through the entire shutdown planning process causing changes in shutdown scheduling of later projects, and possibly extending the duration of the shutdown.
Any delays in the startup of the upgraded facilities may result in changes to the production department plans for supplying customers. Without a current set of the plans and schedule the upsets that occur early in the shutdown operations can produce unnecessary complications and delays near the end of the shutdown.
With qualified and experienced personnel from Process Technical Services assisting in the shutdown scheduling process, the time to develop the original shutdown schedule and update it during the operations phase of the shutdown will be done more quickly and with fewer chances for error.