Introduction

Question 1

When did the Bhopal Disaster occur?

Answer 1

December 2, 1984

Question 2

What happened during the Bhopal Disaster?

Answer 2

A pesticide plant released 30 tons of highly toxic gas (methyl isocyanate).

Question 3

What were the effects of the Bhopal Disaster?

Answer 3

600,000 people were exposed. The gases stayed low to the ground, causing victims throats and eyes to burn, inducing nausea, and many deaths.

Question 4

What was the death toll of the Bhopal Disaster?

Answer 4

Estimate of 15,000 killed over the years

Question 5

Properties of methyl isocyanate

Answer 5

• highly reactive intermediate for pesticides
• lethal if inhaled or absorbed through skin (0.02 ppm 8-hr threshold limit value)
• Exothermically reacts with water

Question 6

Overview of Bhopal Disaster

Answer 6

Water began to enter the methyl isocyanate storage tank containing over 40 tons of MIC. At that point, the runaway exothermic reaction could not be controlled. The hot MIC vapor was relieved to the atmosphere to the community next to the plant.

Question 7

Bhopal Disaster Safety Systems

Answer 7

vent gas scrubber, flare tower, refrigeration, firewater spray

Question 8

Bhopal Disaster: Vent gas scrubber

Answer 8

Uses caustic soda to neutralize toxic gas exhaust from MIC plant and storage tanks before release thru vent stack or flare) leaking gas could have been detoxified, but the scrubber was turned off

Question 9

Bhopal Disaster: Water curtain

Answer 9

not high enough to reach gas

Question 10

Bhopal Disaster: Flare Tower

Answer 10

designed to burn off gas, but a connecting pipe had been removed for maintenance

Question 11

Bhopal Disaster: Storage Tanks

Answer 11

3 separate storage tanks; water started leaking into one of them causing the runaway heat-producing reaction

Question 12

Bhopal Disaster: Refrigeration System

Answer 12

Freon system to cool liquid MIC was shut down in June to save money and Freon shipped to other plants.

Question 13

Outside factors affecting the Bhopal Disaster

Answer 13

1. Profitability: Plant operating at 1/5 capacity due to weak demand and shifting market
2. Accidents: 6 major chemical safety incidents from 1978-1984
3. Morale: Major cost cutting initiatives had reduced training, maintenance, and staffing
4. Oversight: Government oversight at odds with desire for chemical production entirely in India
5. Site location: Shanty town set up outside plant was legalized in July 1984

Question 14

Hindsight of the Bhopal Disaster

Answer 14

• apply process safety management principles
• Understand the hazards of your process fully
• Define emergency action plans for the “worst case scenario”
• Inherently safer design: MIC was an intermediate chemical and did not need to be stored

Question 15

Beirut, Lebanon Incident

Answer 15

An explosion at a warehouse storing ammonium nitrate killed at least 135 people and injured at least 5000.

Occurred on August 4, 2020

Question 16

Georgetown Toyota Plant Incident

Answer 16

A truck carrying liquid nitrous oxide hooked up to the wrong tank, which held phosphorous, and as a result nitric acid was produced. The hazmat team and local emergency response team flooded the contaminated tank with 3000 gallons of water.

Question 17

Process safety

Answer 17

the measures taken to manage, prevent, or respond to process hazards

Question 18

Personal safety

Answer 18

a component of process safety focused on individual behaviors

Question 19

Which category has the highest percentage of accidents?

Answer 19

Mechanical - 53%
Operator Error - 18%
Design - 10%

Question 20

What do engineers do to prevent accidents?

Answer 20

Define hazards and design for safety which includes:
- Understand the hazards inherent in your system
- Identify risks
- Perform Process Hazard Analysis (PHA)
- Develop and follow standard operating procedures
- Understand how your facility works (including startup, shutdown, and fail-safes)
- Management of change (MOC)
- Contribute to the safety culture of the organization

Question 21

Inherently Safer Design

Answer 21

Rely on chemistry and physics to prevent accidents rather than safety systems (controls, interlocks, redundancy, etc.)
- Minimize: storage of hazardous chemicals
- Substitute: less toxic, flammable, reactive materials
- Moderate: reduce temperature, pressure, corrosiveness
- Simplify: equipment and procedures designed for ease of operation

Question 22

Components of Chemical Process Safety Education

Answer 22

Technical aspects (knowledge), Cultural (behavior and values), Psychomotor (doing things)

Question 23

Bhopal Disaster: Firewater spray pipes

Answer 23

Functional but insufficient height to reach top of vent stack. The firewater spray pipes are used to control escaping gasses, cool over-heated equipment or douse fires)

Question 24

Example of Inherently Safer Design

Answer 24

Bhopal Disaster - because the toxic gas was an intermediate, you can MINIMIZE its storage by reacting it directly to a less hazardous product.