cylinder explosion - the case of the greasy oxygen cylinder
TRANSCRIPT
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Cylinder Explosion—The Case of the Greasy Oxygen Cylinder
P O W E R P O I N T ® T R A I N I N G
Target Audience: This case is most appropriate for workers who work with or around compressed gas cylinders.This session is probably not appropriate for workers who do not have compressed gas cylinders in their work area.
Learning Objectives: This case and its training message primarily have to do with how to store and handle compressed gascylinders – specifically oxygen cylinders. It can be used in conjunction with a complete Compressed Gas Safety TrainingSession, or it can be used as refresher training.
Background for the Trainer:
This training session presents a case study of an actual accident inspected and documented by the Occupational Safetyand Health Administration (OSHA). The case presented in this training session is:
– Accident: 014506299
– Report ID: 0830500
– Inspection: 101591337
You may choose to present this training information in a lecture format, or make the training presentation interactive byengaging your class in discussions that will help them identify facts of the case, potential causes of the accident, and futureaccident prevention measures. In either case, students will benefit by learning from a real-life scenario.
Before beginning your training session, print and make copies of the one-page Case Study Student Handout, which isprovided on the disc. The Case Study Student Handout can be used as a worksheet during the training session, or as atake-away reminder once the training session is complete.
Also, print and make copies of the Case Study Quiz, which is provided on the disc as a fully customizable Worddocument. The students can take the quiz at the end of the training session in order to help reinforce the informationpresented. Note that the same quiz is included at the end of this PowerPoint presentation as actual slides to review in class.
Consider taking pictures of compressed gas cylinders stored and used in your workplace. You can add these pictures to thepresentation by inserting them into existing slides or creating new slides.
Make sure the trainees understand the message as you go along. Periodically ask questions to test their understanding.
Speaker’s Notes:
Welcome everyone. Today we will conduct a case study of an actual accident investigated by the Occupational Safety andHealth Administration (OSHA). This is an actual tragic workplace accident that had real-life implications for the worker,the worker’s family, co-workers, and the employer. The Case Study may be disturbing and may even involve a fatality.
The purpose of this training session is to teach and reinforce the importance of properly handling and storing compressed gascylinders in our workplace in order to prevent tragic accidents. In particular, it deals with how to work with oxygen cylinders.The intention is to learn from the accident and take steps to prevent a similar accident from changing our lives.
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Compressed Gases
Highly pressurized
Cryogenic
Corrosive
Toxic
Highly reactive to oxidizers
Flammable
Dangerous even when inert
Background for the Trainer:
Bring your company’s written safe work practices for storing, handling, and using compressed gas
cylinders for employees to review and discuss.
Speaker’s Notes:
Compressed gases in cylinders are highly pressurized. If the valve or regulator of a compressed gas
cylinder breaks off, the cylinder becomes a very powerful unguided missile and can even break through
brick walls.
Some compressed gases are cryogenic, which means they are very cold and cause rapid freezing. Liquidnitrogen is an example.
Some gases are corrosive and can eat through certain metals. It is essential to use appropriate tank and
pipe materials for these gases. Corrosive gases include: hydrogen chloride, hydrogen bromide, and
ammonia.
Other gases can be very toxic. Some of these gases can be detected by smell and others are odorless,
which makes them especially lethal. Toxic gases include: carbon monoxide, hydrogen sulfide, phosgene,
and hydrogen cyanide.
Oxidizers such as oxygen and fluorine cause flammables and combustibles to burn more readily. Mixing
regulators that once contained oxidizers or putting oil on a regulator that has been in contact with an
oxidizer can result in an explosion.
Flammable gases are used at home and in the workplace. Hydrogen and acetylene are used for welding.
Propane is used for barbecues. Butane is used in gas lighters. Natural gas is used in many homes for
furnaces or gas-powered fireplaces. Many of these gases have little or no odor, which means a leak could
go undetected.
Even gases that are inert and do not have any particular hazardous properties themselves can be
dangerous. Nitrogen gas is nontoxic, nonflammable, and noncorrosive. However, a release of nitrogen is
still dangerous because it will displace the air in an area and cause suffocation.
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Take a Look at the Facts
Employee transferring
oxygen between cylinders
Using a brass tube pigtail
Oxygen and acetylene
cylinders stored together
Exposed oil and grease
Background for the Trainer:
Training Option: Pass out the Case Study Student Handout. You may have the students read the accident
description to themselves before discussing it in the class, or you may use the bullet points on the slide
and the speaker notes below to describe the accident.
Speaker’s Notes:
In this case, an employee was transferring oxygen from a large compressed gas cylinder into a small
cylinder.
The employee was using a brass tube pigtail to transfer the oxygen.
This transfer of oxygen was taking place adjacent to a storage area where both oxygen and acetylene
cylinders were kept.
This area also contained exposed oil and grease.
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Take a Look at the Facts (cont.)
Two other workers in immediate area
Explosion and fire
Three employees killed, five others injured
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Speaker’s Notes:
Two other employees were also working in the immediate area where the oxygen transfer was
taking place.
An explosion and fire occurred.
All three employees in the immediate area of the oxygen transfer were killed.
Two additional employees and three members of the public that were on the property were also seriously
injured.
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What Do You Think Went Wrong?
What could have ignited the explosion and fire?
Do you think it is safe to store oxygen and
acetylene cylinders together?
What is significant about the exposed grease
and oil in the area?
How do you think the brass tube pigtail
contributed to the accident?
Background for the Trainer:
Use the questions on this slide to elicit discussion.
Training options: After reviewing this slide and the accident description, give the class 5-10 minutes to discuss
the accident description in small groups; or ask the students to try to determine some of the facts, potential
causes, and possible prevention measures. In either case, use the Case Study Student Handout as a way to
encourage discussion as you go through this presentation.
Speaker’s Notes:
Let’s take a few minutes and, using the Case Study Student Handout, work in groups to try to determinethe facts of the accident, potential causes of the accident, and possible prevention measures. Then we will
review the Case Study together in class.
Consider some of the questions on this slide when discussing the Case Study in your groups.
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Let’s Review the Causes
Pigtail leaked oxygen during transfer
Pigtail not compatible with oxygen
Grease and oil may have been
on pigtail or cylinder valves
Acetylene is very flammable
Smoking, welding, or a spark
may have ignited the explosion
Background for the Trainer:
Try to get the trainees to put themselves in the place of the person in the case study. What would they have done
in this case? Point out how a near miss can turn into a catastrophe in the presence of emergencies. In this case, the
workers may have become complacent about proper cylinder storage practices because nothing had ever happened
to them.
Speaker’s Notes:
Since the accident report does not specifically say what caused the explosion, we will discuss some of the possible
causes.
It is likely that the brass tube pigtail leaked oxygen during the transfer from the large cylinder to the small cylinder.
This could have occurred because the pigtail was not rated for the high pressure that was contained in the largecylinder, and it leaked. Or, the pigtail may not have been adequately tightened, and it leaked through a seal. Oxygen
will not burn or explode by itself. Oxygen is not a fuel, it merely supports the combustion process. Something would
have to ignite a nearby fuel source for the leaking oxygen to help create an explosion.
Another possibility is that the pigtail was intended to transfer acetylene only and it was not supposed to be used to
transfer oxygen. If this was the case, the pigtail could have contained remnants of acetylene gas – oxygen can beexplosive when combined with acetylene gas. Or, the thread sealant may not have been compatible with oxygen and
actually reacted with the oxygen. It is very important not to exchange a gauge or pigtail from one gas to another. The
results could be disastrous.
With the exposed grease and oil nearby, it is also likely that the pigtail, cylinder valves, or even the cylinders
themselves were contaminated with grease or oil from the worker’s hands. This grease or oil could have provided the
necessary fuel that the leaking oxygen needed.
Acetylene is a very flammable gas that is often used for welding or torch cutting operations. Most acetylene cylinders
are equipped with pressure relief valves to prevent the cylinder from exploding when exposed to high temperatures.
Instead, the pressure relief valve will release acetylene when heated up, which adds fuel to the fire.
The scene is set for a fire – we have leaking oxygen and plenty of fuel sources. Now all that is needed is an ignitionsource. Since we do not know what the other two workers in the immediate area were doing, we can speculate that their
activities may have contributed to igniting the explosion. They could have been welding, or smoking, or using a
hammer to bend a piece of metal – thus causing a spark. Even static electricity could have ignited this fire.
Can you think of any other causes that may have contributed to this accident?
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Let’s Talk About Cylinder Storage
Dry and well ventilated
Away from combustibles, heat sources,and electrical systems
No sparks, smoking, or open flames
Oxygen 20 feet away from fuels
Cylinders upright, secure, valves capped
“Danger” & “Warning” signs prominently posted
Background for the Trainer:
Bring any written procedures your company has for cylinder storage – specifically the storage of
oxygen cylinders.
Show pictures of your company’s cylinder storage area.
Speaker’s Notes:
Cylinder storage areas must be dry and protected from the weather, including rain, snow, and direct
sunlight. The storage area must also be well ventilated to prevent the accumulation of gases if there is
a leak.
Storage areas must be away from combustibles such as wood pallets, cardboard boxes, or rags. Keep heat
sources away from cylinder storage areas. Keep cylinders away from electrical systems so they do not
accidentally become part of an electrical current.
Sparks, open flames, and smoking should not be allowed within 25 feet of cylinder storage areas.
Oxygen cylinders must be stored at least 20 feet away from cylinders containing fuels such as acetylene
or other fuels such as grease and oil. In fact, combustibles such as grease and oil must not be allowed in
cylinder storage areas. It may be necessary to erect a fire wall between the oxygen cylinders and the
cylinders containing fuels.
Store cylinders standing upright. Make sure the cylinders are secured so they cannot be accidentally
knocked over. Make sure all valves are capped to prevent the valve from being damaged if a cylinder does
get knocked over.
Cylinder storage areas also have sign requirements that depend on the type of compressed gas being
stored. Most cylinder storage areas will have signs such as “No smoking, open flames, or sparks” or
“Danger– Compressed Gases.”
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Using Compressed Gas
Keep cylinders upright and secure
Keep away fromflames, sparks, electricity
Keep oil, grease,solvents off cylinders
Open valves slowly by hand
Don’t tamper with safety devices
Background for the Trainer:
Bring any written procedures your company has for using compressed gas cylinders —specifically
oxygen cylinders.
Show pictures of cylinders being used at your company.
Speaker’s Notes:
Always use cylinders in the upright position. If you need to transport cylinders, do so by securing them
in carts or hand trucks specifically designed for this purpose. It is important to make sure they do not
fall over and damage their valve.
When in use, keep cylinders away from open flames, sparks, smoking, electricity, and other sources
of ignition.
Do not work with cylinders when your hands or gloves are contaminated with grease, oil, solvents,
or other fuel sources. It is important to keep cylinders free of oil, grease, and solvents – especiallyoxygen cylinders.
Open cylinder valves slowly by hand. If a tool is needed to open a valve, do not use the cylinder because
the use of a tool may put too much stress on the valve and break it off. Open the valve slowly to prevent
putting a surge of pressure on the regulator and other systems.
Never tamper with any cylinder safety devices. You are only putting yourself and others in danger.
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Don’t Let It Happen to You
Store gas cylinders properly
Use proper regulators and pigtails
Make sure all fittings are sealed
Keep fuel sources away
Keep ignition sources
away from cylinders
Speaker’s Notes:
Let’s take a look at what we can do to prevent a similar incident from happening at our facility.
Store compressed gas cylinders properly. Be sure to separate oxygen cylinders from cylinders
containing flammable or combustible gases.
Use the proper regulators and pigtails. Do not share them between different gases.
Make sure all fittings on regulators, pigtails, etc., are tight and adequately sealed to prevent leaks.
Also, make sure the thread sealant material is compatible with the compressed gas.
Keep fuel sources away from where gas cylinders are used and stored.
Keep ignition sources away from cylinders.
Are there any questions?
Thanks for your attention.
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Quiz
1. Oxygen cylinders must be stored how far away
from cylinders containing fuels?
2. Oxygen is dangerous because it will explode
or burn by itself. True or False
3. Describe one way to secure a cylinder to keep
it from falling.
4. Name at least two ignition sources to keep away
from cylinders.
Background for the Trainer:
Remind employees that the quiz is to encourage further discussion and to help you, the trainer, be
sure that everyone understands what was discussed.
Print copies of the quiz for participants to take on their own, or go over the questions as part of the
training session.
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Quiz (cont.)
5. Where should cylinders be stored?
6. Before handling an oxygen cylinder, make sure
your hands are free of what?
7. When is it safe to share pigtails or regulators
between different types of gases?
8. What is hazardous about acetylene gas?
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Quiz Answers
1. Q. Oxygen cylinders must be stored how far
away from cylinders containing fuels?
A. 20 feet.
2. Q. Oxygen is dangerous because it will explode
or burn by itself. True or False
A. False, oxygen only supports combustion.
It needs a fuel source and ignition source.
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Quiz Answers (cont.)
3. Q. Describe one way to secure a cylinder to
keep it from falling.
A. Chain or tie it to a wall.
4. Q. Name at least two ignition sources to keep
away from cylinders.
A. Open flames, smoking, sparks, static electricity.
5. Q. Where should cylinders be stored?
A. In a dry and well-ventilated location.
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Quiz Answers (cont.)
6. Q. Before handling an oxygen cylinder, make
sure your hands are free of what?
A. Oil, grease, or solvents.
7. Q. When is it safe to share pigtails or regulators
between different types of gases?
A. Never.
8. Q. What is hazardous about acetylene gas?
A. Acetylene is very flammable.
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