Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
1
SAChE® Certificate Program
Level 3, Course 3.3: Common Chemicals and Their Major Hazards
Unit 1 – Ammonium Nitrate, Hydrogen and Ethylene
Narration:
[No narration]
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
2
Getting Started
Narration (male 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
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
3
well as a printable copy of the unit slides and narrative. 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.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
4
About This Training Program
Narration (female voice):
Welcome to the American Institute of Chemical Engineers’ online Process Safety training
program. This course will introduce you to some common industrial chemicals and their major
hazards.
In this course, we will examine nine common chemicals:
1. Ammonium nitrate;
2. Hydrogen;
3. Ethylene;
4. Chlorine;
5. Ammonia;
6. Benzoyl peroxide as an example organic peroxide;
7. Ethylene oxide as an example epoxide;
8. Hydrogen fluoride; and
9. Sulfuric acid.
These chemicals are being covered in this course because they have played a role in numerous
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
5
industrial or transportation incidents that resulted in injury or death. They are also ubiquitous;
due to their wide usage and/or large production volumes, you are likely to encounter these in
your career. When you do, it is important that you are aware of the hazards associated with
them. These are obviously not the only hazardous materials you will encounter in your work but
they are some of the most common.
Technology exists to handle these chemicals safely. As an engineer, you will be part of the team
responsible for ensuring that they are handled properly.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
6
Course Introduction
Narration (female voice):
This course is divided into four units:
• Unit 1 – Ammonium Nitrate, Hydrogen and Ethylene;
• Unit 2 – Chlorine and Ammonia;
• Unit 3 – Organic Peroxides and Epoxides; and
• Unit 4 – Hydrogen Fluoride and Sulfuric Acid.
We have included the discussion of two to three chemicals in each unit simply for the purpose
of organizing the material into four units. The pairing of chemicals in each unit does not imply
that there is a unique relationship between them.
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 of 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.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
7
Objectives
Narration (female voice):
By the end of each unit of this course, you will be able to do the following for all of the
chemicals covered in that unit:
• Identify their common names, the physical states in which they are generally stored and
shipped, and their primary applications;
• Identify the primary hazards associated with the chemicals;
• Identify the inherent characteristics of these chemicals that make them hazardous; and
• Describe incidents that have occurred involving these chemicals.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
8
Types of Hazards
Narration (female voice):
Before we begin to explore individual chemicals, let’s review some key hazard terms. As you
know, hazards in the process industries include:
• Flammability;
• Toxicity;
• Instability; and
• Corrosivity.
[Male voice]
Click each term to review its meaning.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
9
Flammability (Slide Layer)
[When “Flammability” is clicked…]
Flammability is the ability of a substance to ignite and be consumed by fire.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
10
Toxicity (Slide Layer)
[When “Toxicity” is clicked…]
Toxicity is the quality, state, or degree to which a substance is poisonous and/or may chemically
produce an injurious or deadly effect upon introduction into a living organism.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
11
Instability (Slide Layer)
[When “Instability” is clicked…]
Instability is the degree of intrinsic susceptibility of a material to release energy through self-
reaction (polymerizing, decomposing or rearranging).
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
12
Corrosivity (Slide Layer)
[When “Corrosivity” is clicked…]
Corrosivity is the ability of a material to cause visible destruction of, or irreversible damage to,
living tissue by chemical action at the site of contact. These materials can begin to cause
damage as soon as they touch the skin, eyes, respiratory tract or digestive tract.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
13
SECTION 1: Ammonium Nitrate
Narration:
[No narration]
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
14
Description
Narration (female voice):
Let’s begin our exploration of common chemicals with an introduction to ammonium nitrate.
Ammonium nitrate (often referred to by its abbreviation, AN) is a colorless or white crystalline
solid. It’s often sold in the form of a pellet.
AN is a commonly used fertilizer. However, when heated to high temperature, it can become
dangerously unstable and potentially detonate. Later in this section, we’ll review some major
incidents that occurred due to this instability.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
15
Chemical Structure and Properties
Narration (female voice):
Ammonium nitrate has the chemical formula NH4NO3, as illustrated here.
AN is the nitrate salt of the ammonium cation. The nitrate anion makes AN a strong oxidizer.
While not flammable itself, as an oxidizer, AN will accelerate the combustion of other materials.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
16
NFPA 704 Diamond
Narration (female voice):
The National Fire Protection Association (NFPA) Standard 704 diamond is shown here.
The health (left blue), flammability (top red) and instability (right yellow) hazards of a material
are ranked from zero to four with four indicating the highest hazard level. Symbols in the
bottom white diamond indicate special hazards.
The NFPA diamond is intended for use by first responders. It provides a simple, pictorial
summary of the hazards associated with a material under emergency conditions, such as fire or
loss of containment.
For more information on the NFPA diamond, see the SAChE course on Fire Hazards.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
17
NFPA 704 Diamond (continued)
Narration (female voice):
By looking at the NFPA 704 diamond for AN shown here, you can see that AN has a high level of
instability hazard, has no significant health hazard, and is not flammable but can participate in
fire as oxidizer.
[Male voice]
Explore the hazards associated with AN by clicking each colored diamond. When you do, you
will see the NFPA definition of the hazard number shown.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
18
Red diamond (Slide Layer)
[When the red-0 diamond is clicked…]
Will not burn under typical fire conditions.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
19
Yellow diamond (Slide Layer)
[When the yellow-3 diamond is clicked…]
Capable of detonation or explosive decomposition or explosive reaction but requires a strong
initiating source or heating to high temperature under confinement before initiation.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
20
White diamond (Slide Layer)
[When the white-OX diamond is clicked…]
Possesses oxidizing properties.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
21
Blue diamond (Slide Layer)
[When the blue 0 diamond is clicked…]
No hazard beyond that of ordinary combustible material.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
22
Ammonium Nitrate Applications
Narration (female voice):
Now let’s look at applications for ammonium nitrate.
We mentioned that AN is a common fertilizer. The agricultural industry is the largest user of
ammonium nitrate. It’s used directly as a fertilizer and it is also used to produce other fertilizers.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
23
Production of Explosives
Narration (female voice):
Ammonium nitrate is also used as an oxidizer in the production of commercial explosives for
uses such as rock blasting. When ammonium nitrate is combined or contaminated with a
combustible material, such as fuel oil, an explosive mixture exists since the mixture contains
both a fuel and an oxidizer. Since ammonium nitrate and fuel oil are readily available, this
mixture has been used by terrorists, such as the Oklahoma City bomber.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
24
Other Applications
Narration (female voice):
Smaller quantities of ammonium nitrate are used in various other applications, such as:
• A raw material for the production of nitrous oxide gas;
• In the production of vehicle air bags;
• In medical instant cold packs; and
• As a nutrient in the production of antibiotics and yeasts.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
25
Hazards of Ammonium Nitrate
Narration (female voice):
Now let’s look at hazards posed by ammonium nitrate in more detail.
First, as we noted, AN is capable of detonation or explosive decomposition when exposed to a
strong initiating source.
As an oxidizer, AN can react with combustible materials, allowing them to burn without an air
supply (oxygen for combustion is available from the nitrate anion in the AN molecule). If a
material is burning in air, AN can accelerate the combustion. Thus, it is dangerous to store AN
near combustible materials.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
26
Thermal Instability
Narration (female voice):
The greatest hazard of AN is thermal instability. This material is subject to rapid decomposition;
the mechanism and rate of decomposition vary with temperature.
Pure AN is stable at room temperature. Low temperature AN decomposition is endothermic.
The heat input required for this reaction is comparable to that required to boil water. Small
amounts of ammonia and nitric acid vapor may be released at ambient temperatures but this
reaction is not self-accelerating.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
27
Thermal Instability (continued)
Narration (female voice):
Above about 200°C, AN becomes thermally unstable. Decomposition at this temperature
becomes exothermic and self-accelerating. Toxic oxides of nitrogen (NO, NO2, and N2O) plus
water, O2 and N2 are produced. Large volumes of gas are generated.
If a fire is the source of the high temperature, the produced oxygen and nitrogen oxides can
escalate the event by supporting the existing fire as oxidizers.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
28
With Increasing Temperature…
Narration (female voice):
As the temperature rises…
• The rate of decomposition increases; and
• The decomposition reaction becomes more exothermic.
Under the right conditions, the decomposition reaction can reach detonation velocities. Recall
that a detonation occurs when the reaction front moves faster than the speed of sound. The
resulting explosion is much more forceful than other types of explosions. We’ll see some
examples of the force of an AN explosion in a few minutes, when we review incidents involving
this material.
For more information on detonation, see the SAChE course on Explosion Hazards.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
29
Detonation
Narration (female voice):
The detonation of AN can be initiated by:
• A shock produced by an explosive charge; or by
• Heating of the AN to a high temperature under confinement.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
30
Incidents Involving Ammonium Nitrate
Narration (female voice):
We’ll conclude our discussion of ammonium nitrate by presenting a couple of incidents involving
this chemical:
• The SS Grandcamp explosion in Texas City, Texas; and
• The West Texas Fertilizer explosion.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
31
SS Grandcamp, Texas City, Texas
Narration (female voice):
A disaster that occurred in Texas City, Texas shortly after the end of World War II is generally
considered the worst industrial incident in American history. On April 16, 1947, the cargo ship,
SS Grandcamp, was docked in the port of Texas City, Texas. The vessel’s cargo included
approximately 2,100 metric tons of ammonium nitrate packaged in paper bags.
Around 8:00 a.m., smoke was spotted in the cargo hold. Over the next hour, attempts to
extinguish the fire or bring it under control failed.
At 9:12, the vessel detonated, causing enormous destruction throughout the port. The blast
leveled nearly 1,000 buildings and even knocked two planes out of the sky. The official casualty
estimate was 567. More than 5,000 people were injured, with 1,784 admitted to 21 area
hospitals.
You will recall that a strong initiator is required to detonate AN. In this case, the initiator was
high temperature along with confinement. The high temperature was generated by the
preceding fire and the use of steam to try to extinguish the fire. The necessary confinement was
provided by the bags of AN packed together inside the ship’s hold.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
32
Part 2
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
33
West Fertilizer Company Explosion
Narration (female voice):
On April 17, 2013 a fire broke out in a fertilizer storage and distribution facility in the town of
West, Texas. The facility stored large amounts of ammonium nitrate for use as a fertilizer. The
fire caused approximately 27 metric tons of ammonium nitrate to detonate. The initiator was
the same as at Texas City in 1947 – fire-induced high temperature and confined material.
The site itself and buildings near the site were destroyed. The explosion caused 15 fatalities –
most of them firefighters – and many more injuries. It led to extensive damage and destruction
in the town.
[Male voice]
For more details on this event, click the video icon to watch a video produced by the U.S.
Chemical Safety Board (CSB).
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
34
Part 2
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
35
Part 3
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
36
Part 4
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
37
West Texas Video (Slide Layer)
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
38
SECTION 2: Hydrogen
Narration:
[No narration]
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
39
Description
Narration (female voice):
Here in Section 2, we’ll discuss hydrogen.
At standard temperature and pressure, hydrogen is a colorless, odorless, tasteless, non-toxic,
but highly flammable gas. It can be liquefied for storage and transportation. With a normal
boiling point of 20°K, it is cryogenic when in its liquid state.
Hydrogen is widely used in industry.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
40
Chemical Structure and Properties
Narration (female voice):
Hydrogen has the chemical formula H2 and is sometimes referred to by that formula rather than
its full name. With its low molecular weight, it is much lighter than air at ambient conditions.
A large number of tragic industrial incidents have begun with the release of a flammable gas or
vapor. Hydrogen is a highly flammable gas that is used in large quantities. It is easily ignited and
more likely than most other gases to transition from deflagration to detonation when ignited in
a congested area.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
41
NFPA 704 Diamond
Narration (female voice):
The NFPA 704 diamond for H2 is shown here. You can see that flammability is the only
significant hazard of H2 – but it is a serious hazard.
[Male voice]
Click on the colored diamonds if you would like to see the NFPA definitions of the hazard levels
given for H2.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
42
Red diamond (Slide Layer)
[When the red-4 diamond is clicked…]
Burns readily. Rapidly or completely vaporizes at atmospheric pressure and normal ambient
temperature.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
43
Yellow diamond (Slide Layer)
[When the yellow-0 diamond is clicked…]
Normally stable, even under fire conditions.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
44
White diamond (Slide Layer)
[When the white diamond is clicked…]
No special hazards.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
45
Blue diamond (Slide Layer)
[When the blue-0 diamond is clicked…]
No hazard beyond that of ordinary combustible material.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
46
Hydrogen Applications
Narration (female voice):
The primary use of hydrogen is in the production of ammonia.
The next largest single user of hydrogen is oil refineries. These facilities use hydrogen in
processes such as reforming and hydrotreating.
Hydrogen is also used in the production of other chemicals for a variety of industries.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
47
Vehicle Fuel
Narration (female voice):
Liquid hydrogen has long been used as fuel for space travel. Liquid and gaseous hydrogen are
now being used as a fuel for road transportation and in fuel cells.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
48
Hazards of Hydrogen
Narration (female voice):
Now let’s discuss what makes hydrogen so flammable.
The flammability hazard of hydrogen can be quantified using a number of parameters. Let’s look
first at flammability range. A wide range of hydrogen/air mixtures will ignite. In other words,
hydrogen has a large flammability range. The range is much larger than that of typical
hydrocarbons, as you can see by the lower flammable limits (LFLs) and upper flammable limits
(UFLs) listed in this table.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
49
Easily Ignited (Low MIE)
Narration (female voice):
Hydrogen is also easily ignited. Note from this table that hydrogen has a much lower minimum
ignition energy (MIE) than that typical of hydrocarbons.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
50
Minimum Oxygen Required
Narration (female voice):
Hydrogen does not need a lot of oxygen to burn. The limiting oxygen concentration (LOC) of
hydrogen is lower than that typical of hydrocarbons.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
51
Explosion Potential, Particularly in Congested Areas
Narration (female voice):
Once ignited, hydrogen has the potential to produce violent vapor cloud explosions (VCEs).
Beware of the use or storage of hydrogen in congested process areas or near pipe racks, as
these areas are particularly susceptible to hydrogen vapor cloud explosions.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
52
High Flame Speed
Narration (female voice):
Additionally, due to hydrogen’s high flame speed, it is more likely than most gases to transition
from a deflagration to detonation in a congested area.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
53
Potential Mitigating Factor – Density
Narration (female voice):
A mitigating factor with regards to hydrogen’s flammability hazard is its density. Being much
lighter than air, hydrogen will disperse quickly if it can escape upward when released.
This is not true of hydrogen vaporizing from spilled liquid. The very low temperature of the
vapor initially causes it to be heavier than ambient air until it warms up.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
54
Leaks are Difficult to Detect
Narration (female voice):
Hydrogen has an additional fire hazard. As we mentioned, H2 is a colorless, odorless gas. It
burns with a pale blue, almost invisible flame. Thus, a hydrogen leak is difficult to detect.
The use of flame resistant clothing (FRC) is critical when working anywhere hydrogen is used or
stored since you could walk into a hydrogen flame without seeing it!
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
55
Incidents Involving Hydrogen
Narration (female voice):
On the next couple of slides, we’ll review two incidents involving hydrogen:
• The Hindenburg airship disaster; and
• The Silver Eagle Refinery incident.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
56
Hindenburg Airship Disaster
Narration (female voice):
In May of 1937, the Hindenburg was completing its flight from Frankfurt, Germany to Lakehurst,
New Jersey. Onboard the large airship were 36 passengers and 61 crew members.
While attempting to moor, the airship suddenly burst into flames. A spark may have ignited the
hydrogen used to provide lift for the airship. Rapidly falling 200 feet to the ground, the fabric
skin of the vessel incinerated within seconds. Thirteen passengers, 21 crewmen, and one civilian
member of the ground crew died. Most of the survivors suffered substantial injuries.
After this event, airship travel was no longer popular. Modern blimps are filled with helium, an
inert gas, rather than hydrogen.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
57
Part 2
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
58
Part 3
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
59
Silver Eagle Refinery
Narration (female voice):
A massive explosion and fire occurred at the Silver Eagle Refinery on November 4, 2009, in
Woods Cross, Utah. The incident was caused by a rupture of a pipe that had become
dangerously thin from corrosion.
The catastrophic rupture occurred in a ten-inch pipe at the bottom of a reactor. The rupture led
to a massive release of hydrogen, which caught fire quickly. A vapor cloud explosion (VCE) sent a
blast wave across the refinery into a subdivision. The blast wave damaged over 100 homes, two
severely. One home was knocked off its foundation.
Fortunately, no one was seriously injured. There were four workers near the process unit at the
time of the explosion. They were blown to the ground but were not seriously injured. A fifth
worker escaped injury by just minutes, having been taking readings next to the pipe that failed
just one to two minutes before the release.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
60
SECTION 3: Ethylene
Narration:
[No narration]
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
61
Description
Narration (female voice):
In this last section of Unit 1, we’ll discuss ethylene. Ethylene is a highly flammable, colorless gas.
It is called ethene by the International Union of Pure and Applied Chemistry (IUPAC).
Ethylene is widely used as an intermediate in the chemical industry. It is one of the largest
volume organic chemicals produced globally.
Ethylene is typically transported as a compressed gas or as a cryogenic liquid with a boiling point
of -104°C.
The primary hazards of ethylene are fire and explosion. It is important to know that, like
hydrogen, ethylene is more likely than most gases to transition from deflagration to detonation
when ignited in a congested area. Unlike hydrogen, ethylene has significant instability and
toxicity hazards as well.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
62
Chemical Structure
Narration (female voice):
The chemical formula for ethylene is C2H4. The double carbon-carbon bond makes ethylene
more reactive than alkanes like ethane. The breaking of this bond is accompanied by a high
energy release.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
63
NFPA 704 Diamond
Narration (female voice):
The NFPA 704 diamond for ethylene is shown here. Note the high flammability hazard and less
severe toxicity and instability hazards.
[Male voice]
Click on the colored diamonds to see the definitions of the hazard levels shown.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
64
Red diamond (Slide Layer)
[When the red-4 diamond is clicked…]
Burns readily. Rapidly or completely vaporizes at atmospheric pressure and normal ambient
temperature.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
65
Yellow diamond (Slide Layer)
[When the yellow-2 diamond is clicked…]
Readily undergoes violent chemical changes at elevated temperatures and pressures.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
66
White diamond (Slide Layer)
[When the white diamond is clicked…]
No special hazards.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
67
Blue diamond (Slide Layer)
[When the blue-2 diamond is clicked…]
Can cause temporary incapacitation or residual injury.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
68
Ethylene Applications
Narration (female voice):
Ethylene is primarily used as a monomer for the production of polyethylene. Large quantities of
ethylene are required because polyethylene is the most widely used plastic in the world.
Ethylene is also widely used as an intermediate in the chemical industry, including in the
production of other plastics, anti-freeze solutions and solvents.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
69
Hazards of Ethylene
Narration (female voice):
There are flammability, instability, and health concerns associated with ethylene.
Ethylene is highly flammable; therefore, fire and explosion are its primary hazards.
Ethylene also has polymerization and decomposition hazards, but elevated temperature is
required for these reactions to occur.
Finally, ethylene is toxic, but exposure to relatively high concentrations is required for there to
be adverse health effects. Exposure to thousands of parts per million may cause headache,
dizziness, anesthesia, drowsiness, or other central nervous system effects.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
70
Flammable and Explosive
Narration (female voice):
Some of the properties of ethylene that cause it to be a highly flammable gas are its wide
flammability range and low minimum ignition energy, or MIE.
The flammability range at atmospheric pressure is about three to 36%, broader than the two to
10% range typical of hydrocarbons.
Ethylene’s MIE is low – just 0.06 millijoules. This is not as low as the 0.018 millijoules of
hydrogen but well below that of methane at 0.28 millijoules. This low MIE means it does not
take a very strong ignition source to ignite ethylene.
Finally, like hydrogen, ethylene is more likely than other gases to transition from a deflagration
to detonation in congested areas. This means that ethylene explosions can, under certain
conditions, be very forceful.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
71
Dispersion
Narration (female voice):
Unlike hydrogen, ethylene does not disperse easily. At ambient temperature, ethylene is only
slightly lighter than air and cold ethylene gas evolved from cryogenic liquid is heavier than air.
The American Chemistry Council (ACC) reports that a flammable ethylene cloud can extend up
to 0.8 kilometers beyond the visible fog of a large low temperature leak.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
72
Instability
Narration (female voice):
Hazardous polymerization of ethylene can occur at high temperatures or in the presence of
materials such as activated carbon or molecular sieve.
Decomposition with rapid pressure build-up can occur at temperatures above 180°C and
pressure above 1136 kilopascal.
Explosions have occurred in pipelines due to heating by compression and during ethylene drying
operations.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
73
Incident Involving Ethylene
Narration (female voice):
Before we conclude our discussion of ethylene, let’s examine an incident that demonstrates the
force with which ethylene can explode.
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
74
Phillips 66
Narration (female voice):
On October 23, 1989, a massive explosion demolished the Phillips 66 Company polyethylene
plant in Pasadena, Texas (a Houston suburb), when more than 38,500 kilograms of ethylene
dissolved in isobutane was instantaneously released to the atmosphere.
The incident investigation indicated that a block valve thought to be closed during a
maintenance operation on a high density polyethylene reactor was actually open. A product
plug was all that kept the high temperature/high pressure reactor contents from venting to the
atmosphere. At about 1:00 pm, more than 99% of the reactor contents were released almost
instantaneously when the plug apparently broke loose.
Within 90 to 120 seconds, this gas mixture found an unidentified ignition source and exploded
with the force of 2.2 metric tons of TNT. The initial explosion threw debris 8 kilometers and
shattered windows a kilometer away. It registered between 3 and 4 on the Richter scale on
Houston’s Rice University seismographs. Following this initial explosion, there was a series of
further explosions and fires. One eye-witness reported hearing ten explosions that afternoon.
In all, 23 lives were lost and 314 people were injured. More than 100 workers trapped by the
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
75
fire were rescued by U.S. Coast Guard fireboats and evacuated across the Houston Ship Canal.
Capital losses were initially estimated at over $715 million. Business disruption losses were
nearly as great, $700 million.
Part 2
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
76
Part 3
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
77
Part 4
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
78
Part 5
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
79
Part 6
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
80
Part 7
Copyright ©American Institute of Chemical Engineers 2018. All rights reserved.
81
Unit 1 Summary
Narration (female voice):
We’ve reached the end of the first unit in the Common Chemicals and Their Major Hazards
course. Having completed this unit, titled “Ammonium Nitrate, Hydrogen and Ethylene,” you
should now be able to do the following for each of the three chemicals discussed in this unit:
• Identify their common names, the physical states in which they are generally stored and
shipped, and their primary applications;
• Identify the primary hazards associated with the chemicals;
• Identify the inherent characteristics of these chemicals that make them hazardous; and
• Describe incidents that have occurred involving these chemicals.
In Unit 2, we’ll explore chlorine and ammonia. But first, please take the quiz for Unit 1 beginning
on the next slide.
Top Related