Question
In the spring of 2020, one of Seaburg's clients, a chlorine complex in nearby McIntosh, Alabama, was operating at 1OO percent of capacity-sold-out. A maintenance
In the spring of 2020, one of Seaburg's clients, a chlorine complex in nearby McIntosh, Alabama, was operating at 1OO percent of capacity-"sold-out." A maintenance turnaround was scheduled, however, to perform major repairs to the facility. Turnaround activities, expected times for their completion, and sequencing constraints were as shown in Table 1 (below)
It should be noted from the above sequencing constraints that job C (removal of the existing chlorine compressor and installation of a new unit) constrained job N (changing the heat exchanger on the first effect evaporator) because a large crane was needed for both jobs. Plans called for the crane to perform the compressor job (C) before moving to the heat exchanger job (N). Seaburg’s staff advised the production manager that a second crane could be rented so that both jobs could be performed simultaneously. The rental of the crane would cost a base fee of $10,000 plus $8,000 per day. Contribution to profit and overhead from the production complex was estimated at $40,000 per day.
Activity | Predecessors | Normal Time(hours) | Normal time (days) | Crash Time (hours) | crash time (days) | Crash Cost |
A | None | 8 | 1 | 0 | 0 | |
B | None | 16 | 2 | 8 | 1 | $15,000 |
C | A | 72 | 9 | 48 | 6 | $50,000 |
D | A | 16 | 2 | 0 | 0 | |
E | A | 24 | 3 | 16 | 2 | $10,000 |
F | A | 36 | 4.5 | 24 | 3 | $15,000 |
G | A | 10 | 1.25 | 0 | 0 | |
H | A | 16 | 2 | 0 | 0 | |
I | B | 24 | 3 | 0 | 0 | |
J | B | 24 | 3 | 0 | 0 | |
K | B | 16 | 2 | 8 | 1 | $15,000 |
L | B | 8 | 1 | 0 | 0 | |
M | CDEFGH | 24 | 3 | 16 | 2 | $35,000 |
N | BC | 48 | 6 | 0 | 0 | |
O | IJKLM | 8 | 1 | 0 | 0 | |
P | MNO | 8 | 1 | 0 | 0 |
- Should the second crane be rented? What is the minimal cost or maximum profit resulting from using the second crane? Assume in the analysis that “8” hours is equivalent to “one” days operation. Also assume that Seaburg construction owns a crane and that their are no cost associated with it’s operation for this case. Therefore, only the cost of the second crane is applicable for your analysis. Use crashing.
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