Case Study in Engineering Flashcards
1
Q
What is the Socratic method
A
The Socratic Method (470-399 BCE)
- Form of cooperative argumentative dialogue
- Based on asking and answering questions to stimulate critical thinking and draw out ideas and underlying presumptions
- He believed human choice was always motivated by inner desire for happiness
2
Q
How can an engineer use Socratic method?
A
To analyse a situation to derive ethical judgement based on the inner self
3
Q
What is NSPE
A
USA national society of professional engineers
4
Q
What are the fundamental principles of NSPE
A
- Hold paramount the safety, health and welfare of public
- Perform services in area of competency
- Issue public statement in an objective and truthful manner
- Act for employer or client as a faithful agent and trustees
- Avoid deceptive acts
- Conduct themselves honourably, responsibly and lawfully so as to enhance honour, reputation and usefulness of the profession
5
Q
What is the Oppenheimer’s Dilemma
A
(Father of the atomic bomb)
- On July 1945, the first ever atomic bomb was detonated and in Aug 1945 two atomic bombs were dropped on Hiroshima and Nagasaki, which caused the Japanese to surrender.
- Instead, he felt responsible for the ensuing arms race and threat to civilisation brought about by the bomb
- Due to his complex moral code, he objected to the development of the H-bomb (social and political consequences)
6
Q
Case A: Disaster at Bhopal - The Plant Background
A
- Manufactured pesticides in India
- Part of India’s Green Revolution
- Increase the productivity of crops
1) Plant initially welcomed at Bhopal for its economic potential
2) Located 2 miles from city centre; surrounding population expanded significantly after construction
3) Government classified plant as “general” (not “hazardous”) industry in 1976, even after approving MIC-based processes at plant and establishing a “hazardous industry” zone 15 miles from city.
7
Q
Case A: Why was Bhopal Chosen
A
- It’s central location in India
- A railway system that spanned the country
- Large lake = reliable source of water
- Sufficient electricity and labor to sustain a large scale industrial plant
8
Q
Case A: When was the disaster and what happened?
A
- December 2nd, 1984
- There was a leak in the storage tank at a Union Carbide chemical plant
- The tank contained 10,000 gallons of MIC (Methyl Isocyanide)
- The leak sent a toxic cloud of gas over the surrounding slums of Bhopal, resulting in the death of over 10,000 people and 200,000 more getting injured
9
Q
Case A: What was the impact from the disaster at Bhopal?
A
- Over 10,000 deaths in the first three days of the gas leak
- Additional 25,000 people died of related injuries by 1994
10
Q
Case A: What caused the leakage at Bhopal?
A
- The leak was attributed to the leakage of water (valve not properly closed) into the MIC storage tank during maintenance
- Water reacts vigorously with MIC, causing heating of the liquid
11
Q
Case A: What happens when water is mixed with MIC?
A
- Mixing of water with MIC increased the temperature of the liquid in the tank to 400F causing MIC to vaporise
- Leading to a build up of high pressure within the tank
- When internal pressure became high enough, a pressure relief valve opened, leaking MIC vapour into the air
12
Q
Case A: What was the root cause of the incident?
A
- There were several factors that led to the disaster
- A major factor was the curtailment of plant maintenance as part of a cost cutting effort
13
Q
Case A: What was wrong with the storage tank?
A
- The MIC tank had a refrigeration unit on it, which should have kept the tank temperatures closer to normal
- This tank stopped working 5 months before the accident and has not been repaired
- Tank was equipped with an alarm, which should have alerted plant workers to the dangerous temperatures
- The alarm was improperly set, no warning was given
14
Q
Case A: What is the purpose of the flare tower, and what happened?
A
- The flare tower was designed to burn vapours before they enter the atmosphere
- it would have been able to reduce, if not eliminate, the amount of damage
- The flare was not functioning
15
Q
Case A: What is the purpose of the scrubber and what happened?
A
- Scrubber: used to neutralise toxic vapours
- This was not activated until the vapour release was already in progress.
16
Q
Case A: Who was responsible for the Disaster at Bhopal?
A
Plant designers - did their job, although with some safety features under design
- Management of the plant seems obviously negligent
- Union Carbide also seems negligent in not preparing a plan for notifying and evacuating the surrounding population in the event of an accident.
- Indian government: Blamed for not putting some safety standards
- Local government: No policy or zoning forbidding squatters and others from living to close to a power plant
- Bulk of the blame goes to UC, for failure to adequately train and supervise its Indian employers in the maintenance and safety procedures that are taken for granted.
17
Q
Case A: What were the consequences from the disaster at Bhopal?
A
- Casualties - over 10,000 people
- Injured over 200,000 more
- UC paid $250 billion for the lawsuits
- UC also helped set up job training and relocation programs for the victims of the accident
- Approximately 10,000 victims will suffer from permanent damage
18
Q
Case B: Challenger disaster - Give a brief overview of what happened?
A
- January 26, 1986, 7 astronauts killed whilst piloting the Challenger Space Shuttle
- Challenger exploded seconds after takeoff due to the failure of rocket booster O-rings
19
Q
Case B: What are the 3 components of the Challenger shuttle?
A
- Liquid rocket booster
- Solid rocket booster
- Orbiter
20
Q
Case B: What was the timeline/ when did the shuttle explode?
A
- The shuttle exploded ~73 seconds after launch
- Two rocket boosters crisscrossed and continued flying wildly.
- The right booster, identifiable by its failure plume, is now at the left of the non-defective counterpart
21
Q
Case B: Explain the design of the Challenger
A
- Designed to be a reusable launch vehicle
- A key aspect of the booster design = joints where the individual cylinders come together
- Joints are sealed by two O-rings
22
Q
Case B: O-rings:
- What are they made of?
- What was their purpose
- Why did they cause problems to the program timeline?
A
- Made from synthetic rubber
- Designed to prevent hot gases from the combustion of the solid propellant from escaping
- They were previously found to be inadequate and redesigned causing delays in the program
23
Q
Case B: What was the political climate before the Challenger disaster?
- NASA’s Budget
- European Space authority
- President Reagan
And what role does the socratic method play in all this?
A
- NASA’s budget was determined by congress who was unhappy with the delays of the shuttle
- European space authority was developing what seemed to be a cheaper alternative to the shuttle
NASA felt pressure to get the challenger launched on time so that the next shuttle launch was to carry a probe to examine Halley’s comet before Russians launch
- President Reagan was planning to mention the shuttle and a special astronaut - the first teacher in space - Christa McAuliffe before the upcoming state-of-the-union address.
Socratic method: one should not be concerned about these issues! One should make judgements based on safety, health and welfare to derive an ethical judgement fulfilling his inner-self happiness.
24
Q
Case B: What happened to the weather the days before the launch?
A
- First launch date was postponed due to cold front expected to move through the area
- Again another cold front was expected with temperatures in the low 20s(F) by the new launch time
25
Case B: What happened the night before the launch?
| 1. Role of Morton Thiokol
- 14 engineers at Morton Thiokol had unanimously and vigorously voiced opposition to the launch.
Boisjoly "Too cold, delay launch! Until 53 F"
- They warned that the launch site temperatures were below the safety range
- Engineers were aware of a history of concern over these seals, which had shown alarming erosion in precious launches and were already being redesigned (o-rings)
26
Case B: What did they say would happen if the temperatures were too low?
- Low temperatures can make O-rings less pliable and cause them to fail
- Because o-rings are supposed to form the seals between segments of the booster rockets
27
Case B: What happened during the launch?
- Contrary to the weather predictions, the temperature was 28F
- Due to the low temperatures, the O-ring didn't set properly
- The shuttle exploded 73 seconds after lift off on 28th Jan 1986
28
Case B: What was the aftermath from the Challenger disaster?
- President Ronald Reagan
- What did the investigation reveal
- What happened to Boisjoly
1. Reagan ordered a presidential commission to review the disaster, Boisjoly was one of the witnesses called
2. investigation: revealed that long before the disaster, Boisjoly sent a memo describing the O-ring problem to his managers but was apparently ignored
3. Boisjoly set up a task force to address this issue, but the task force had no resources, so it was eventually shut down. Then he took a medical retirement
29
Case B: What else could Boisjoly have done?
External whistleblowing
30
Case B: Epilogue, what did NASA and Boisjoly do following the accident?
1. NASA
- Several families sued NASA
- Between 2-3.5million per family
- Morthon Thiokol paying 60%
2. Boisjoly
- Testified before congress
- Left the company
- Underwent therapy for PTSD
- Became a speaker on workplace ethics
- Awarded the prize for scientific freedom from the AAAS
- Died of cancer in 2012
31
Case C: Briefly describe what happened
Nicoll Highway collapse (Singapore)
| - 4 casualties, crane operator, construction worker, inspector of works and construction supervisor
32
Case C: When did it happen and what happen?
Tuesday 20th April 2004 around 330pm
- Temporary retaining wall of the tunnel at the MRT circle line construction collapsed
- Caused a cave-in and brought the surrounding area and the highway down into it, forming 30m deep ravine
33
Case C: What were the impacts from the incident?
1. Gas water and electricity
2. Police action
3. Excavation workers for the circle line
4. Cost of damages
1. Gas water and electricity
- Cables snapped, causing power to go out for about 15,000 people and 700 businesses in the Marina and Suntec City area
2. Police action
- police had to cordon off the adjoining Merdeka Bridge and seal all roads leading to Nicoll Highway, affecting thousands of commuters
3. Excavation workers for the circle line
- Excavation works at the circle line sites were temporarily suspended
4. Cost of damages
- The cost of damages arising from the disaster was estimated to run into the millions and Nicoll highway opened again after 8 months
34
Case C: What is the cut and cover method?
- Cut and cover method used to construct the underground tunnels between the Nicoll highway and boulevard stations
- Large cavity, with retaining concrete walls is progressively excavated from ground level to tunnel depth, which in this case was 33m
- As the cavity gets deeper, the retaining walls are braced with a strut-waler support system
- This system comprises of steel bars which are connected to bars running parallel to the walls (walers).
35
Case C: What is the strut-waler support system?
This system comprises of steel bars (struts) which are connected to bars running parallel to the walls (walers).
The purpose of the walers is to distribute the forces exerted by the struts along a larger surface area of wall/ When work is completed within the cavity, it is filled back with soil
36
Case C: What happened post-collapse?
At about 3.30pm on 20th April 2004, a collapse occurred at part of the excavation site known as type M3. This was directly adjacent to the Nicoll highway
At the time of collapse the cavity had reached about 30m in depth
37
Case C: What caused the collapse?
2 critical reasons
what did these design errors result in
1. Under-design of the diaphragm wall using Method A
- Finite element analysis of ground conditions used the mechanical properties of drained soil - known as Method A when the data for undrained soils should be used
2. Under-design of the waler connection in the strutting system
- About 10% underestimation of strut loads at level 9
- 50% underestimate of wall bending moments
- 50% underestimate of wall deflections
These design errors resulted in the eventual failure of the 9th level strut-waler connections together with the inability of the overall temporary retaining wall system to resist the redistributed loads as the 9th level strutting failed. The catastrophic collapse then ensued.
38
Case C: What are the area of competences?
| For engineers
1. Engineer - should offer services, advice or undertake professional assignments only in their areas of competence (NSPE code of ethics)
- Includes exercising care and communicating clearly
- Also includes the responsibility to call for and to obtain the services of a specialist or an expert if required
- Requirement not just about maintaining a proper standard of care, actually involves honesty with one's client of employer or oneself
39
Case C: Nishimatsu Contruction company
| - What consequences did they face?
1. Max fine of 200,000 (New laws have increased this to 500,000)
2. Spent additional $11.7 millions on rescue operations, reconstruction, checks on nearby buildings
3. Barred from further contracts for 5 years
4. Damage to reputation
40
Case C: What happened to Ng Seng Yoong of LTA
1. Project director
2. Ng was told to investigate alert levels more than 2 months before the incident and his reply failed to satisfy the BCU
3. By submitting an assessment endorsed by the professional engineer for temporary works, Paul Broome, and not by himself, Ng had not compiled his duties as a qualified person
* An offence under section 19(1) of the building control act for breaching condition 8 of the statutory duties in the conditions of permit, issued pursuant to section 7(2) of the same and imposed on him as the Qualified person of project C824
- Guilty, fined $8000 also faced disciplinary action under the Professional Engineers act
41
Case C: What were the lessons learnt from this incident?
- Structural safety of temporary works is as important as that of permanent works
- Structures should be designed according to established codes (e.g. construction safety handbook) and checked by competent persons
- Monitoring and instrumentation during construction must be meticulously undertaken with an eye to safety
42
Case D: What happened with the Chandrayaan-2 launch?
- India's first moon lander was postponed at the very last 56 minutes on 15th July 2019 due to suspected "technical snag"
- Discovered whilst filling the rocket with cryogenic fuel even though the conditions were pressing to go ahead:
1. Top scientists and VIPs were gathered
2. The skies were cleared and "India's Space Dreams" (being the fourth country to land on the moon were about to happen)
43
Case D: What role did the Socratic method play in this incident?
- Prioritised safety and the engineer convinced his superior and his company to address the problem before external whistle-blowing
- They did not launch and everyone was safe
