Rigor/Relevance
Framework
LESSON PLAN
Lesson Title Introduction to Oxygen/Acetylene (OxyAcetylene) Cutting
Knowledge
Area and/or Course Introduction to Welding
6
5
4
3
2
1
C
D
Assimilation
_______
Adaptation
___X____
A
B
Acquisition
_______
Application
_______
1
No. Periods 1 (73-minute period)
2
3
4
Application
Teacher Goal(s):
1. Students will demonstrate how to safely set up an
Oxy-acetylene cutting torch, and ignite the welding
torch
2. Students will practice cutting metal using the Oxyacetylene Torch
Objectives:
The student will be able to (TSWBT). (Oregon Skill Set numbers in parentheses at the
end of the objective statement.)
1. Describe the set-up and shut-down process for an Oxy-acetylene cutting torch (AG
10.02.01.04)
2. Demonstrate igniting the acetylene gas and properly adjusting the flame (AG 10.02.01.04)
3. Describe the process for making proper cuts using an Oxy-acetylene torch (CS.EF.02)
4. Demonstrate cutting metal with the Oxy-acetylene torch (EL.HS.RE.08)
5. Evaluate torch cuts against industry standards, using problem solving methods (CS.PS.06)
State Standards met by Objectives:
Subject
Strand
1. Agriculture
AG 10.02.01.04
2. CRLS
CS.EF.02
3. CRLS
CS.HS.02
4. CRLS
4. English
CS.PS.06
EL.HS.RE.08
Eligible Content
Demonstrate the set up and adjustment of tools and
equipment
Select, apply, and maintain tools and technologies
appropriate for the workplace.
Listen attentively and summarize key elements of
verbal and non-verbal communication.
Assess results and take corrective action.
Understand, learn, and use new vocabulary that is
introduced and taught directly through
informational text, literary text, and instruction
across the subject areas.
Knowledge: 1=awareness; 2=comprehension; 3=application; 4=analysis; 5=synthesis; 6=evaluation
Application: 1=knowledge in one discipline; 2=apply knowledge in one discipline; 3=apply knowledge across disciplines; 4=apply knowledge to real-world predictable situations; 5=apply
knowledge to real-world unpredictable situations
5
Materials, Equipment, Audio-Visual Aids:
References:
1. Oxygen/Acetylene welding torch
http://www.artmetal.com/brambush/forum/
bramyak3/messages/9.html
2. Gloves
3. Welding face shield
4. Striker
5. Various metal
http://www.stanford.edu/group/prl/
documents/html/OAweld.htm
http://www.ehow.com/how_4897643_useoxyacetylene-cutting-torch.html
Anticipatory Set/Introduction/Motivation/Interest Approach:
Review Yesterday’s Lesson:
When you are evaluating your MIG welds; what are some things to look for?
(Q) Why does your weld look thin?
(A) My travel was too fast
(Q) Why is there excessive spatter on your metal?
(A) I was too far away
(Q) What are some ways for you to go slower
(A) Use a method such as half-moons or circles to create a motion instead of just pulling the
puddle straight
(Q) Why is your bead too tall?
(A) Too slow
Set:
Teacher’s personal story
When I was in high school we had an O/A torch and a plasma cutter, most of use chose to use the
plasma cutter. Does anyone know why? A plasma cutter is a piece of equipment used to cut
metal, but it requires much less skill than the O/A torch, it makes much cleaner cuts using forced
air. It was a very good piece of equipment to use except for what happened when I went back
home for the summer and my Dad asked me to cut off a piece of metal for him? Did I have the
skill to run the O/A torch?
I was at a disadvantage because I never learned how to properly use the torch, and properly
practice it. The O/A torch is important to learn because most people who have small shops or
farms are likely to have the oxy-acetylene torch over a plasma cutter.
Transition (Use Objective):
1. Describe the set-up and shut-down process for an Oxy-acetylene cutting torch
2. Demonstrate igniting the acetylene gas and properly adjusting the flame
3. Describe the process for making proper cuts using an Oxy-acetylene torch
4. Demonstrate cutting metal with the Oxy-acetylene torch
5. Evaluate torch cuts against industry standards, using problem solving methods
Strategy – Includes Teacher
Activity, Student Activity,
Questions/Answers and
Objectives
Subject Matter Outline/Problem and Solution (Application
Points Lace in Throughout Lesson) (Modeling, Guided
Practice, and Content)
Objective #1
Setting up the O/A System, and shutting it down
In a review of safety, the
teacher will ask questions
about O/A system.
(Q) Why do we double check
to make sure the tanks are
secured to the cart?
Turn the valve on the top of the oxygen
tank all the way open. These valves work
fine if only partially opened, but the shaft
should be sealed when the valve is fully
opened. This prevents a leak an
accidental loss of oxygen.
(A) Because we don’t want the
tanks falling over
(Q) What can happen if the top
is sheared off of the tank?
Turn the valve on the acetylene tank 1/4
to 1/3 of a turn to open. Gas will flow
freely at this setting but the tank will be
quick to close in the event of a fire.
(A) Rocket
(Q) What is the pressure where
acetylene becomes unstable?
(A) 15 p.s.i.
The teacher will then ask the
students to help with the set up
of the O/A system. Questions
are designed to get students
thinking about why we turn the
O/A system on in a certain
manner. This part of the lesson
is a review from Introduction
to O/A welding
(Q) Why is the oxygen tank
valve opened all the way, but
the acetylene only opened ¼ of
a turn?
Verify that the oxygen valve on the
cutting torch is closed.
Fully open the oxygen valve on the torch
handle by turning it counterclockwise.
Crack open the cutting torch oxygen valve so that a very slight
oxygen flow is started.
Light the torch by making a spark with the spark lighter at the
end of the cutting tip while also opening the acetylene valve
slightly.
Adjust the two valves (cutting torch
oxygen and acetylene) until the strongest
flame is obtained. The flame should have
a short, bright blue flame at the torch tip
and no yellow in the flame.
(A) So we can more easily turn
the acetylene tank off if
Adjust the acetylene regulator to approximately 10 psi. Turn
needed.
the screw in to increase the pressure and out to decrease it.
(Q) There are two pressure
indicators on each tank; what
are their purposes?
(A) The one on the right is
usually tank pressure and the
pressure valve is on the left is
for line pressure.
Adjust the oxygen regulator in the same manner to a pressure
in the 40 to 60 psi range.
Adjust the acetylene and oxygen valves as necessary to
maintain the correct flame.
Objective #2
Striking the Cutting Torch
(Q) Why do we only open the
acetylene valve a little bit
RIGHT before we are ready to
strike?
Open the acetylene torch valve about one-quarter turn. Light
the acetylene with a spark from a "striker". Do not use matches
or a butane lighter.
(A) So we do not have an
explosion with too much
acetylene
(Q) Should there be any
oxygen in the mix when we
are lighting the torch?
(A) No, we do not add oxygen
until we have an acetylene
flame properly adjusted
(Q) After we have lighted the
acetylene; what do we want
our flame to look like?
Adjust the flame, using the acetylene
torch valve until the flame has just lost its
"smoky" quality. If the flame "blows out"
or blows away from the tip of the torch,
the valve is too far open. If the flame
jumps away from the torch tip, you have
it too far open. Close the valve a bit and
then slowly reopen.
With the proper shade gas welding lens over your eyes (#4-7),
slowly open up the oxygen torch valve. A small, pointy flame
very close to the torch tip will appear. This is called the
�inner cone'. At the same time, a distinct, blue flame will
begin to appear at the end of the flame. Continue to slowly
open up the oxygen torch valve until the distinct blue flame has
just shrunk to the same size as the inner cone. This is the proper
welding flame called a neutral flame.
(A) No black smoke, but the
tip of the flame is just
feathering
Objective #3
Using the Oxy-acetylene Cutting Torch
The teacher will demonstrate
how to use the Oxy-acetylene
torch so the students can
visualize the concepts. Each
student will also practice the
torch operation in front of
their peers.
Ensure that the piece to be cut is positioned such that no part of
the support is under the cut line. Cutting torches can cut several
inches of steel easily, so anything in the path could be
damaged.
Hold the torch close to the work. The bright blue portion of the
flame should just touch the edge of the area to be cut.
(Q) Has anyone in the class
every used oxyacetylene for
cutting?
Heat the work until the edge starts to glow. There may be small
sparks start to come off the metal at this point.
(Q) What do you do if the
torch starts popping?
Press down on the cutting lever and open it fully. Move the
torch along the line you want to cut. The
speed of your movement will depend on
the thickness of the metal and the size tip
on the torch. The proper speed will be
result in a continual stream of sparks as
the metal is cut. You should go as fast as
you can control the torch and get
continual cutting. This will reduce the
slag on the cut edge.
(A) Move the tip away from
the metal
Shut off the torch when done. Close the acetylene valve first,
then the cutting tip oxygen.
(Q) When you were watching
me cut; how close was the tip?
Close the tank valves.
(Q) Why do we wait for the
metal to become red hot before
we forcefully add oxygen?
(A) So the metal will fall away
from the metal easier
(A) The blue part of the flame
was almost touching the metal
Open the acetylene valve on the torch to purge the gas from the
hose. Then press the cutting lever to purge the oxygen hose.
Finally, close the oxygen valve on the torch handle.
Objective #4 & #5
Demonstrating and Evaluating Oxy-acetylene Cutting
The teacher will ask students
to practice making cuts.
Using an oxyacetylene torch, makes a straight and clean cut
with the proper combination of travel speed, flame height,
pressures, torch angle, and flame intensity
Students will work in pairs for
cutting, and students will
evaluate each other’s welds
according to industry
standards
a. Uses proper tip size for the job
b. Opens valve slowly on both tanks
c. Checks tanks for leaks
(Q) How does the cut compare
to the industry standard?
(A) more slag
(Q) What causes the build up
of excessive slag?
(A) Moving the torch too slow
(Q) What type of flame do we
actually cut with?
d. Sets the flow gauge regulators to correct setting for the task
e. Never allows rate of tank withdrawal to exceed
approximately 1/7 of tank capacity per hour (to cause release of
solvent and tank debris, damaging system)
f. Adjusts the oxygen and acetylene flow to achieve a precise
neutral flame
i. bright blue inner cone
ii. no pale orange or “feather” present (carburizing flame)
(A) The same as welding, a
neutral flame
(Q) What is happening when
we hear the torch pop?
iii. no shrill sound or sharper, less bright cone (oxidizing
flame)
g. Performs the cutting task smoothly without excessive
“popping” (caused by an oxidizingflame) and “blow back”
(A) Something is wrong with
our operation of the torch or an h. Uses appropriate cutting guides when needed
incorrect mixture of gases is
being used.
i. Finished cut is straight, smooth, and clean
(Q) If there is a band on the
cutting edge; what is the
problem?
(A) The height of the tip was
too far above the metal
i. proper cutting technique (little or no slag at bottom of cut)
ii. proper height of tip above material (no black band on the cut
edge)
iii. proper travel speed and oxygen pressure (top of cut edge is
not rounded)
iv. neutral flame is maintained (no splatter buildup on tip)
j. Properly shuts down the torch and tanks
Closure/Summary/Conclusion (Tie in Objectives)
What have we learned about using the Oxy-acetylene cutting torch?
1. Describe the set-up and shut-down process for an Oxy-acetylene cutting torch
2. Demonstrate igniting the acetylene gas and properly adjusting the flame
3. Describe the process for making proper cuts using an Oxy-acetylene torch
4. Demonstrate cutting metal with the Oxy-acetylene torch
5. Evaluate torch cuts against industry standards, using problem solving methods
Evaluation: (Authentic forms of Evaluation, Quizzes, or Written Exam)
Visual and verbal checks for understanding will be done by the teacher to ensure the students are
understanding the concepts of O/A cutting and striking the torch
Self-evaluation
Assignments: (Student Activities Involved in Lesson/Designed to Meet Objectives)
Daily calendar
Self-evaluation
Set up and shut down procedural check sheet
Lesson Reflection
This lesson was similar to the O/A welding lesson, so I was able to use the set up process of the
lesson to check for student comprehension of the process. I allowed students to use their
procedural check sheet for answering my questions on setting up the system, to increase the
value of the check sheet. I think I would keep that part of the lesson, but I might not do as much
peer evaluation because students actually seemed to tell each other they had good cuts, just so
they didn’t hurt people’s feelings.