level 2, course 3: chemical reactivity hazards

Copyright ©American Institute of Chemical Engineers 2017. All rights reserved.

1

SAChE® Certificate Program

Level 2, Course 3: Chemical Reactivity Hazards

Unit 1 – An Introduction to Chemical Reactivity Hazards

Narration:

[No narration]


2

Getting Started

Narration (female voice):

If this is your first time taking a SAChE course, please take a few minutes to explore the interface.

This slide will explain how to use the controls to navigate through the course. All of the units in

the course use the same interface. This interface has four main features that you should be

aware of:

• Here is the left navigation bar. It contains a list of the slides as well as the narrative

transcript. At any point in the course, if you would like to revisit any content, click the

slide title to jump back.

• You may also use the Previous button on the bottom of the player. To advance forward,

use the Next button.

• The Search feature allows you to search for content using any word in the current unit.

• On the top menu bar you will find the Help, Abbreviations, Glossary, Resources and Exit

options. The resources included in this course include any unit-specific attachment as

well as a printable copy of the unit slides and narrative.


3

• Use the Exit tab to leave this unit at any time.

Click the arrows if you want to learn more about the interface features. Click ‘Next’ when you’re

ready to continue.


4

About This Training Program

Narration (male voice):

Welcome to the American Institute of Chemical Engineers’ online Process Safety training

program. This course will introduce you to chemical reactivity hazards. It is divided into three

units:

• Unit 1 - An Introduction to Chemical Reactivity Hazards;

• Unit 2 - Uncontrolled Chemical Reactions; and

• Unit 3 - Identifying Incompatibilities and Providing Controls and Safeguards.

Each unit takes about 30 to 45 minutes to complete. At the end of each unit, you will be

presented with a quiz. You must pass the quiz in order to have the unit marked as complete, so

be sure to pay close attention to the content and answer all the review questions along the way.

After completing all of the units in the course, you will take a final exam. You must pass the

exam to have the course marked as completed.


5

Objectives


By the end of this first unit, titled “An Introduction to Chemical Reactivity Hazards,” you will be

able to:

• Describe three major process safety incidents that were related to uncontrolled

chemical reactions; and

• Define "chemical reactivity hazard" and recognize the various types of reactivity hazards.


6

SECTION 1: Significant Incidents Involving Chemical Reactivity

Narration:

[No narration]

Section 1


7

Chemical Reactivity


In this first section, we’re going to examine some major incidents involving chemical reactivity

that caused property damage, environmental damage, harm to human health and even death.

After reviewing these events, some outside the chemical process industries might question why

facilities are using reactive chemicals at all. So let’s first consider how society benefits from

chemical reactivity.


8

Benefits of Chemical Reactivity


Here are just a few examples where chemicals are intentionally reacted to create useful

products:

• In the petrochemicals industry, ethylene is catalytically polymerized to form

polyethylene, which is used for plastic containers, films, pipes and many other uses;

• In the pulp and paper industry, chlorine dioxide is used as a strong oxidizer to bleach

wood pulp in the production of paper products;

• In the mining industry, slurry explosives that rapidly decompose when subject to a

strong initiating source are used in rock blasting;

• In the pharmaceutical industry, predominantly organic reactions are used to

manufacture countless substances beneficial to human health.


Take a few minutes to consider other industries where chemicals are intentionally reacted. Type


9

these examples on the notepaper on the screen before continuing. Click the ‘Submit’ button

after completing your entries. Don’t worry; your entries are not being scored for accuracy; this is

just a brainstorming exercise.

[After making an entry on the notebook paper and clicking ‘Submit.’]

Here are some other industries where chemicals are intentionally reacted. How does this list

compare to the examples you typed?

Part 2


10

Significant Incidents Involving Chemical Reactivity


Problems can occur when intended chemical reactions get out of control or when unintentional

reactions occur. We will learn about the various types of chemical reactivity hazards later in this

unit.

There have been many cases over the past few decades where unintended or uncontrolled

chemical reactions caused significant property damage, negative health effects, and even led to

multiple deaths. Sometimes these incidents impact just the facility where the chemical process

was taking place; but in other cases, both the processing facility and the surrounding community

were tragically impacted.

In this section we are going to explore three of these incidents:

• The Union Carbide incident that occurred in Bhopal, India in 1984;

• The AZF fertilizer factory incident that occurred in Toulouse, France in 2001; and

• The T2 Laboratories incident that occurred in Jacksonville, Florida in 2007.


11

Union Carbide – Bhopal, India (1984)


Let’s begin with the Bhopal disaster. This event took place at a Union Carbide pesticide plant in

Bhopal, India in 1984. To date, this incident remains the most serious industrial disaster ever to

occur, harming people as well as the environment. Watch this brief video for an overview of the

incident.


12

Video: Reflections on Bhopal After 30 Years (Slide Layer)


13

Union Carbide – Bhopal, India (1984) (continued)


As indicated in the video, due to a massive release of a toxic vapor called methyl isocyanate, or

MIC, over 2,000 people in surrounding communities died immediately and thousands more died

later from toxic vapor-related illnesses. Tens of thousands of people suffered health effects from

exposure to the gas. The effects of the incident are still evident today, decades later.

Methyl isocyanate attacks the respiratory system, eyes and skin. It can injure the lungs and

bronchial airways, cause permanent eye damage, and cause death from various forms of

respiratory distress.


14

Part 2


15

Union Carbide – Bhopal, India (1984) – Compounding Factors


After extensive investigation, the immediate cause was identified as water being somehow

added to a storage tank of MIC. MIC is water reactive and, as a result, the pressure and

temperature increased inside the storage vessel to the point where the MIC was released

through the emergency relief system.

There were a number of compounding factors that led to the Bhopal disaster:

• A storage tank was filled beyond recommended capacity.

• The vessel refrigeration system was down for six months to save money; the coolant was being

used elsewhere.

• A relief system caustic scrubber was inactive (said to be down for maintenance).

• The flare downstream of the scrubber was also shut down (said to be awaiting replacement of

corroded pipe work).

• A fixed water curtain used to absorb MIC vapors was insufficient to reach the cloud.


16

• Supervision was slow to react to initial reports of MIC odor in the area; this was coffee break

time (up to an hour may have been lost here).

• A shanty town had been allowed to form along the plant perimeter over a number of years.

• And an effective emergency communication/response system was not in place.


17

Union Carbide – Bhopal, India (1984) – Schematic


This is a schematic of the process system. Click the numbered dots to explore the conditions of

the plant on the day of the incident.

[When [1] is clicked...]

The MIC refrigeration system was out of commission and Tank 610 could not be cooled to slow

down the reaction.


The caustic scrubber was shut down for long delayed maintenance.


Toxic MIC vapor is released from the top of the scrubber vent line at a height of 33 meters.


The flare tower was out of service, awaiting long-delayed replacement of corroded piping.



18

The poorly designed water curtain only reached a maximum height of 15 meters. This height

was insufficient to mitigate the toxic MIC cloud at 33 meters.


19

AZF – Toulouse, France (2001)


Let’s look at another industrial incident involving chemical reactivity.

At the AZF/Grande Paroisse plant in Toulouse, France, production rejects of ammonium nitrate

granules were stored in a warehouse. On the morning of September 21, 2001, 300 metric tons

of the ammonium nitrate granules underwent a decomposition reaction that was fast enough to

be explosively violent.

The incident caused 31 deaths, hundreds of injuries (most from flying broken glass), and

enormous property damage (the whole city was impacted; over 50,000 windows were broken).

According to insurance company estimates, the damage was valued between 1.5 and 2.3 billion

Euros (approximately 1.4 to 2.1 billion U.S. dollars at the time).


20

AZF – Toulouse, France (2001) (continued)


Here is the apparent sequence of events compiled from investigations of the incident…

For unexplained reasons, a major underground explosion took place at a neighboring military

plant. The explosion was recorded as being equivalent to a 3.4 magnitude earthquake.

This tremor triggered the detonation of a 500-pound bomb that was beneath the warehouse

where the ammonium nitrate was stored. The bomb had been dropped in the area during World

War II and had remained buried under the warehouse at the plant.

The bomb blast provided a strong initiator, causing the ammonium nitrate in the warehouse to

explosively decompose.


21

Part 2


22

T2 Laboratories – Jacksonville, Florida (2007)


Let’s look at one more major loss event involving chemical reactivity. This incident took place at

T2 Laboratories in Jacksonville, Florida in 2007. Watch this video for an overview of the incident.


23

T2 Laboratories – Jacksonville, Florida (2007) (continued)


As you just learned from the video of the T2 Laboratories event, four employees were killed and

32 others were injured (including members of the public in the surrounding areas). Debris from

the reactor was found up to a mile away.


24

T2 Laboratories – Jacksonville, Florida (2007) – Findings


The plant was producing methylcyclopentadienyl manganese tricarbonyl (MCMT), a gasoline

additive used to reduce knocking in vehicle engines and other internal combustion engines.

One of the most significant findings by the U.S. Chemical Safety Board (CSB) investigation was

that neither the owners nor operators of the processing facility were aware of all of the

potential hazards associated with the reactions in the facility.

Other findings included:

• The cooling system employed was susceptible to single point failures due to a lack of design

redundancy; and

• The MCMT reactor relief system was incapable of relieving the pressure from a runaway

reaction.

After examining the evidence, it was concluded that the cooling water supply to the reactor

jacket was lost. The heat of reaction was not removed because of this lack of cooling. Thus, the


25

reactor contents heated up into the range where a more severe second exothermic reaction

occurred; the staff and management at T2 did not fully comprehend the extreme severity of this

secondary reaction.

This incident led the CSB to recommend changes to undergraduate chemical engineering

education in the U.S. so that new engineers carefully consider process safety - particularly

chemical reactivity - in their work.


26

SECTION 2: Chemical Reactivity Hazards

Narration:

[No narration]


27

What is a Chemical Reactivity Hazard?


In this section, we’ll learn about hazards associated with chemically reactive materials.

A chemical reactivity hazard is a situation with the potential for an uncontrolled chemical

reaction that can result directly or indirectly in serious harm to people, property or the

environment. The uncontrolled chemical reaction might be accompanied by a temperature

increase, pressure increase, gas evolution or other form of energy release.


28

Runaway Reaction


As part of this discussion, you should know the meaning of the term, “runaway reaction.” A

runaway reaction is a thermally unstable reaction system which exhibits an uncontrolled

accelerating rate of reaction leading to rapid increases in temperature and pressure.

A runaway reaction occurs when the energy and products released by the reaction are not able

to be safely absorbed by the reaction environment (such as the vessel in which it is otherwise

contained).

The incident that occurred at the T2 Laboratories plant in Jacksonville, Florida was a result of a

runaway reaction due in part to a lack of cooling of the reactor.


29

Endothermic vs. Exothermic Reactions


Two other terms that you should be familiar with are endothermic and exothermic reactions.

Click the buttons to review each term.


30

Endothermic (Slide Layer)

[When “Endothermic” is clicked…]

Endothermic refers to a physical or chemical change that requires or is accompanied by the

absorption of heat. Endothermic reactions represent a potential hazard if gaseous or highly

volatile products are generated. In addition, the end product of the endothermic reaction will

generally have greater energy content than the starting materials, so the product itself may be a

reactive material.


31

Exothermic (Slide Layer)

[When “Exothermic” is clicked…]

Exothermic refers to a physical or chemical change accompanied by the evolution of heat; that is,

heat from the system is released to its surroundings. If this heat release is not safely absorbed

by the surroundings, a hazardous situation can occur. For example, the heat of reaction may

vaporize and cause the release of a volatile solvent.

Exothermic reactions with all reactants initially present have the potential for a runaway

reaction leading to a dramatic increase in temperature, pressure (if the reaction is contained)

and reaction rate.


32

Reactivity Hazards


Recall from the beginning of this section that a chemical reactivity hazard is a situation with the

potential for an uncontrolled chemical reaction that can result directly or indirectly in serious

harm to people, property or the environment. There are two basic types of chemical reactivity

hazards….

Those that are a result of self-reactive materials, which include materials that are:

• Polymerizing;

• Decomposing; and

• Rearranging...

...and those that are the result of reactive interactions from materials that are:

• Reactive with atmospheric oxygen;

• Reactive with water;

• Reactive with ordinary combustible materials; and

• Chemically incompatible.

We'll learn more about these two types of reactivity hazards on the slides that follow.


33

Polymerizing Materials


Polymerizing materials are those in which two or more small molecules combine to form larger

molecules during the chemical reaction. A hazardous polymerization reaction is a reaction which

takes place at a rate which releases a large amount of energy.

In 2006, Synthron Inc., a paint additive manufacturer, intentionally used polymerization in a

reactor at its facility in Morganton, North Carolina. The manufacturer changed its process to

meet the needs of a customer. This change resulted in a rapid pressure increase in the reactor.

Solvent vapors vented from the reactor’s manway, forming a flammable cloud inside the

building. The vapors found an ignition source, and the resulting confined vapor explosion and

fires killed one worker and injured 14 others.


Click the video icon to see a CSB video about the incident.


34

Synthron Explosion (Slide Layer)


35

Decomposing Materials


Decomposition is the breakdown of a material or substance (initiated by some form of energy

input) into simpler compounds that are the decomposition products. We have already examined

one major incident (at Toulouse, France) involving the decomposition of ammonium nitrate.

The importance of decomposition in the study of chemical reactivity hazards is that the

decomposition reaction can release a large amount of energy very rapidly. In addition,

decomposition products often present different hazards than the original material.

Decomposing materials can be shock-sensitive and/or thermally-sensitive. The rate at which

decomposition reactions occur varies greatly, from slow to nearly instantaneous.

A 2001 incident at the BP Amoco Polymers facility in Augusta, Georgia was partially due to

thermal decomposition. Three workers died as a result of the incident.


Click the video icon to see a CSB video about the incident.


36

BP Amoco Decomposition Incident (Slide Layer)


37

Rearranging Materials


Rearranging materials may result in disproportionation, isomerization or tautomerization. Click

each term to learn about it.


38

Disproportionation (Slide Layer)

[When “Disproportionation” is clicked…]

Disproportionation is a chemical reaction in which a single compound serves as both oxidizing

and reducing agent and is thereby converted into a more oxidized and a more reduced

derivative. For example, with appropriate heating, a hypochlorite yields a chlorate and a

chloride.


39

Isomerization (Slide Layer)

[When “Isomerization” is clicked…]

Isomerization is the conversion of a chemical with a given molecular formula to another

compound with the same molecular formula but a different molecular structure. Examples

include the isomerization of ethylene oxide to acetaldehyde (both C2H4O) and butane to

isobutane (both C4H10).


40

Tautomerization (Slide Layer)

[When “Tautomerization” is clicked…]

Tautomerization refers to the conversion of one isomer into another organic compound that

differ from one another in the position of a hydrogen atom and a double bond.


41

Materials that are Reactive with Oxygen


There are several types of materials that are reactive with oxygen, which of course is readily

available in the atmosphere. These include materials that are:

• Pyrophoric;

• Flammable;

• Combustible; and

• Peroxide forming.

These terms are listed in order of decreasing rate of reaction.

Click the terms for definitions of each.


42

Pyrophoric (Slide Layer)

[When “Pyrophoric/spontaneously combustible” is clicked…]

A pyrophoric material spontaneously ignites upon exposure to atmospheric oxygen. Note that

the definition of pyrophoric often includes a maximum temperature, such as 54.4°C, or a

maximum time to ignition, such as five minutes. Examples include aluminum alkyls, Grignard

reagents, metal hydrides, and iron sulfide.


43

Flammable (Slide Layer)

[When “Flammable” is clicked…]

A gas that can burn with a flame if mixed with a gaseous oxidizer, such as air or chlorine, and

then ignited. The term “flammable gas” includes vapors from flammable or combustible liquids

above their flash points.


44

Combustible (Slide Layer)

[When “Combustible” is clicked…]

A material that is capable of burning.


45

Peroxide-forming (Slide Layer)

[When “Peroxide forming” is clicked…]

A material that will react with oxygen in the atmosphere to form unstable peroxides, which in

turn might explosively decompose if concentrated. Peroxide formation, or peroxidation, usually

happens slowly over time, when a peroxide-forming liquid is stored with limited access to air. A

peroxide is a chemical compound that contains the peroxy (O-O) group, which may be

considered a derivative of hydrogen peroxide (HOOH). Examples of peroxide formers include

1,3-butadiene and isopropyl ether.


46

Materials that are Reactive with Water


A water-reactive material is one that will react upon contact with water under normal ambient

conditions, including materials that react violently with water and other materials that react

slower but can generate heat or gases that can result in elevated pressure if contained.

Recall from the Bhopal disaster presented earlier in this unit that the prevailing conclusion is

that water was introduced to a MIC storage vessel through an instrument connection, causing a

dramatic chain of events.


47

Oxidizers


An oxidizer is a material that readily yields oxygen or other oxidizing gas, or that readily reacts to

promote or initiate combustion of combustible materials.

Examples of oxidizing gases include bromine, chlorine, and fluorine. Other examples of oxidizers

include hypochlorites, nitrites, and organic peroxides.


48

Chemical Incompatibility


You have nearly completed this first unit in the Chemical Reactivity Hazards course. There is one

more type of chemical reactivity hazard. This is known as chemical incompatibility.

Two (or more) materials are incompatible if they produce an undesired chemical reaction when

combined together under a defined scenario. You will learn more about chemical incompatibility

in Unit 3 of this course.


49

Unit 1 Summary


We’ve reached the end of the first unit in the Chemical Reactivity Hazards course. Having

completed this first unit titled “An Introduction to Chemical Reactivity Hazards,” you should now

be able to:

• Describe three major process safety incidents that were related to uncontrolled

chemical reactions; and

• Define "chemical reactivity hazard" and recognize the various types of reactivity hazards.

In Unit 2, you will learn how uncontrolled chemical reactions can lead to process safety

incidents; you will also learn where to look for chemical reactivity hazards. But first, please take

the quiz for Unit 1 beginning on the next slide.

level 2, course 3: chemical reactivity hazards

Documents