roject Management
Shale Oil Company
Shale Oil Companys Aston, Ohio, manufacturing complex comprises several operating units. These units process the crude oil that is pumped through and transform it into a multitude of hydrocarbon products. The units run 24 hours a day, 7 days a week, and must be shut down for maintenance on a predetermined schedule. One such unit is Distillation Unit No. 5, or DU5. Studies have shown that DU5 can operate only 3 years without major equipment breakdowns, and excessive loss of efficiency. Therefore, DU5 is shut down every 3 years for cleaning, inspection, and repairs.
DU5 is the only distillation unit for crude oil in the Aston complex, and its shutdown severely affects all other operating units. Some of the production can be compensated for by Shale refineries in other locations, but the rest must be processed and stored before the shutdown. Without proper planning, a nationwide shortage of Shale gasoline could occur. The time of DU5s shutdown is critical, and the length of time the unit is down must be kept to a minimum to limit production loss. Shale uses PERT as a planning and controlling tool to minimize shutdown time.
The first phase of a shutdown is to open and clean the equipment. Inspectors can then enter the unit and examine the damage. Once damages are determined, the needed repairs can be carried out. Repair times can vary considerably, depending on what damage the inspection reveals. Based on previous inspection records, some repair work is known ahead of time. Thorough cleaning of the equipment is also known to improve the units operating efficiency. The table below lists the many maintenance activities and their estimated completion times.
DISCUSSION QUESTIONS
1. Determine the expected shutdown time and the probability that the shutdown can be completed 1 week earlier.
2. What are the probabilities that Shale finishes the maintenance project 1, 2, 3, 4, 5, or 6 days earlier?
3.Shale Oil is considering increasing the budget to shorten the shutdown. How do you suggest the company proceed?
Preventive Maintenance of DU5
ActivitiesTime Estimates (in Days)
OptimisticMost LikelyPessimistic
1-2Circulate wash water throughout unit122.5
2-3Install blinds1.522.5
3-4Open and clean vessels and columns234
3-5Open and clean heat exchangers; remove tube bundles123
3-6Open and clean furnaces124
3-7Open and clean mechanical equipment22.53
3-8Inspect instrumentation245
4-9Inspect vessels and columns123
5-10Inspect heat-exchanger shells11.52
5-11Inspect tube bundles11.52
6-12Inspect furnaces22.53
6-17Retube furnaces152030
7-13Inspect mechanical equipment11.52
7-18Install new pump mechanical seals358
8-19Repair instrumentation3815
9-14Repair vessels and columns142128
10-16Repair heat-exchanger shells1510
11-15Repair tube bundles; retube2510
12-17Repair furnaces51020
13-18Repair mechanical equipment101525
14-20Test and close vessels and columns458
15-16Install tube bundles into heat-exchanger shells123
16-20Test and close heat exchangers122.5
17-20Test and close furnaces123
18-20Test and close mechanical equipment123
19-20Test instrumentation246
20-21Pull blinds1.522.5
21-22Purge all equipment with steam135
22-23Start up unit3510