Production Operations and Management[1]

Production and Operations Management Module 2 HW-1 Submitted by Group 2 1 Akhila Vydugula 2 Shreya Vishwas 3 Bhavana Yadav Krishnappa 4 Sohan Shylaja Mohan Shale Oil Case Study Network diagrams are used by the project management technique PERT (Program Evaluation and Review Technique) to predict the amount of time needed for project tasks. The PERT (Program Evaluation and Review Technique) 4-way technique using AON (Activity-on-Node) entails a structured study of project activities and dependencies. It consists of the following key elements:  Define Activities and Sequence.  Determine Activity Durations and Time Estimates.  Create Project Network Using AON.  Determine Critical Path and Slack. Let’s calculate Expected time and variance using the below formulas: T exp = (a+4m+b)/6 Variance=[(b-a)/6] 2 No . Activity Optimisti c Most Likely(m ) Pessimistic(b ) Predecessor Expecte d time Varianc e 1 Circulate wash water throughout unit 1 2 2.5 - 1.9 0.06 2 Install blinds 1.5 2 2.5 1 2.0 0.03 3 Open and clean vessels and columns 2 3 4 2 3.0 0.11 4 Open and clean heat exchangers; remove tube bundles 1 2 3 2 2.0 0.11 5 Open and clean 1 2 4 2 2.2 0.25

furnaces 6 Open and clean mechanical equipment 2 2.5 3 2 2.5 0.03 7 Inspect instrumentatio n 2 4 5 2 3.8 0.25 8 Inspect vessels and columns 1 2 3 3 2.0 0.11 9 Inspect heat-exchanger shells 1 1.5 2 4 1.5 0.03 10 Inspect tube bundles 1 1.5 2 4 1.5 0.03 11 Inspect furnaces 2 2.5 3 5 2.5 0.03 12 Retube furnaces 15 20 30 5 20.8 6.25 13 Inspect mechanical equipment 1 1.5 2 6 1.5 0.03 14 Install new pump mechanical seals 3 5 8 6 5.2 0.69 15 Repair instrumentatio n 3 8 15 7 8.3 4.00 16 Repair vessels and columns 14 21 28 8 21.0 5.44 17 Repair heat-exchanger shells 1 5 10 9 5.2 2.25 18 Repair tube bundles; retube 2 5 10 10 5.3 1.78 19 Repair furnaces 5 10 20 11 10.8 6.25 20 Repair mechanical equipment 10 15 25 13 15.8 6.25 21 Test and close vessels and columns 4 5 8 16 5.3 0.44 22 Install tube bundles into heat-exchanger shells 1 2 3 18 2.0 0.11 23 Test and close 1 2 2.5 17, 22 1.9 0.06

Activities that have Zero slack value are considered critical. These are the tasks that will postpone the project's completion if they are not completed on time. From the above diagram we identified the critical path as 1-2-3-8-16-21-27-28-29 . So these are the activities that are critical. No Critical Activity Expected Time 1 Circulate wash water throughout unit 1.9 2 Install blinds 2.0 3 Open and clean vessels and columns 3.0 8 Inspect vessels and columns 2.0 16 Repair vessels and columns 21.0 21 Test and close vessels and columns 5.3 27 Pull blinds 2.0 28 Purge all equipment with steam 3.0 29 Start up unit 5.5 Total= 45.7 Critical activities time = 45.7 Days The expected time for all activities(Critical+ Non-Critical) = 146.7 Days Critical Activities percentage= (45.7/146.7 )*100 = 31.15% 6) List all non-critical activities. All activities with slack value>0 are non-critical activities. Delaying these activities does not affect the project completion time. From the above diagram we can list them as: No Non-Critical Activities 4 Open and clean heat exchangers; remove tube bundles 5 Open and clean furnaces 6 Open and clean mechanical equipment 7 Inspect instrumentation 9 Inspect heat-exchanger shells 10 Inspect tube bundles 11 Inspect furnaces 12 Retube furnaces 13 Inspect mechanical equipment 14 Install new pump mechanical seals 15 Repair instrumentation 17 Repair heat-exchanger shells 18 Repair tube bundles; retube

19 Repair furnaces 20 Repair mechanical equipment 22 Install tube bundles into heat-exchanger shells 23 Test and close heat exchangers 24 Test and close furnaces 25 Test and close mechanical equipment 26 Test instrumentation 7) What is the probability that the shutdown can be completed 4 days earlier than expected project completion time. To calculate the probability of completing the project 4 days earlier than expected project completion. We need project variance and standard deviation.

Using above calculations we can draw the statistical graph, X