Transcribed TextTranscribed Text

Case study Read the following case study and answer the questions which follow. Cover-Shield Failure and Falling Incident at a Hydroelectric Generating Station Ontario Power Generation, located on a dam on the St. Lawrence River near Cornwall is the second-largest hydro power station in Ontario. It contains typical hydroelectric equipment such as turbines, generators, a repair shop (called the erection bay), and a 300- ton gantry crane (a moving, four-legged overhead structure). It is an outdoor type of generating station, where the 16 generators are located across the dam, side by side, and are easily accessible by the gantry crane. The crane is used to handle generators in need of repair. It moves on rails and can be moved into the erection bay. The erection bay is a closed structure near shore on the dam, with a huge door that can be opened to let the crane in. The door opening measures 20 meters by 20 meters. The door is powered by a motor. A drive shaft runs across the top of the door opening. The drive shaft has sections joined by three chain-type couplings (see Figure 1). The cast-aluminum covers that are mounted over the couplings (see Figure 2) rotate with the couplings as the drive shaft turns to operate the door. The coupling covers are made up of two sections. Each section weighs approximately 3 kg. The two mating surfaces of the coupling cover sections are joined by two bolts. There are no nuts used. At approximately 11:00 a.m. on Saturday, October 30, 1999, a maintenance technician started to open the erection bay door from the inside push-button station on the south side of the door. The door had raised approximately 2 meters when he heard a noise at the north side of the door and saw something fall to the erection bay floor. He stopped the door and went to investigate. The technician found two halves of a drive-shaft coupling cover and two bolts for securing the coupling cover on the floor. The coupling cover was from the north drive-shaft coupling. After the incident, the door was isolated. The coupling cover was bolted back on the coupling. Also, the covers on the two other drive shaft couplings were inspected. Two bolts on the south coupling cover had to be tightened 1/8 turn each. One bolt on the center coupling cover was tight and the other bolt had to be tightened 1/8 turn. The door was returned to service. The incident wasreported to the station manager, who rated the incident as “potentially high risk.” The level of investigation is more detailed for the high-risk incidents. The erection bay door is original to the station and maintenance responsibilities were turned over to the station in January 1960. The 1960 document includes manufacturer servicing instructions. Inspections of door components should be scheduled on a monthly to six-month basis.The inspectionsshould include checks of oil levels, chains, brakes, cables, and gear cases. The maintenance file on the bay door was not complete. It showed that mechanical maintenance was done on the door in 1983, 1984, 1989, and 1996. The work in 1989 was described as “emergency inspection and repair” and was performed by an external service provider. The work in 1996 was conducted with technical assistance from an external service provider. This door is categorized as non-production equipment. According to Ontario Power Generation, “[Non-production equipment] are the lowest-priority systems and work on these systems often gets deferred. However, maintenance on these structures/systems cannot be forgotten as eventually this will lead to failures which will have an overall impact on the facility.” Figure 1 Figure 2 Answer the following questions 1. The erection bay door has been relegated to breakdown (emergency) maintenance status during the last 20 years or so (as opposed to periodic inspection and preventive maintenance recommended by the manufacturer). Give argumentsfor and against this change in maintenance policy. 2. Is there a design problem in the cover shield assembly? Explain your answer Is there a simple fix? Explain your answer 3. Were there adequate breakdown (emergency) maintenance plans in place on the day of the incident? Why? 4. What do you think Ontario Power Generation Company should do?

Solution PreviewSolution Preview

These solutions may offer step-by-step problem-solving explanations or good writing examples that include modern styles of formatting and construction of bibliographies out of text citations and references. Students may use these solutions for personal skill-building and practice. Unethical use is strictly forbidden.

Question 1: In my opinion, I am against keeping the erection bay door with only breakdown/ emergency maintenance for many reasons. First of all, periodic inspection and preventive maintenance is highly recommended by the manufacturer because this type of equipment needs to be checked periodically in order to avoid the consequences of any interruption.
Moreover, the cost of breaking down might, and indeed, in most cases overweight the cost of preventing and periodic inspection....

By purchasing this solution you'll be able to access the following files:

50% discount

$20.00 $10.00
for this solution

or FREE if you
register a new account!

PayPal, G Pay, ApplePay, Amazon Pay, and all major credit cards accepted.

Find A Tutor

View available Industrial Engineering Tutors

Get College Homework Help.

Are you sure you don't want to upload any files?

Fast tutor response requires as much info as possible.

Upload a file
Continue without uploading

We couldn't find that subject.
Please select the best match from the list below.

We'll send you an email right away. If it's not in your inbox, check your spam folder.

  • 1
  • 2
  • 3
Live Chats