OxyFuel EquipmentSection 7

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Introduction

Oxyfuel welding is a fusion welding process that uses oxygen and a fuel gas to provide the heat and shielding for welding.

Requirements

An oxyfuel system must:1 store the two gasses,

2 regulate the pressure,

3 set the flow rate,

4 mix the gasses,

5 deliver the mixed gasses to the weld.

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Fuel Gasses

Propane (LPG)Natural GasAcetyleneMAPPHydrogen

What are the advantages and disadvantages of each gas?

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Uses

How many people have used an oxyfuel system?

Is there anything else that it be used for?

Why has the use of oxyfuel welding declined?

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OxyFuel Safety

Remember safety is based on a conscious decision and the management of hazards.

What hazards are associated with an oxyfuel system?

How do we manage these hazards?

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OxyFuel system

Before learning to use an oxyfuel system, it is important to know the name and function of each part.

A. Oxygen safety discB. Oxygen cylinder valveC. Oxygen cylinder pressure

gaugeD. Oxygen working pressure

gaugeE. Oxygen regulatorF. Oxygen regulator adjusting

screw

G. Acetylene cylinder safety disc

H. Acetylene cylinder valve

I. Acetylene cylinder pressure gauge

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OxyFuel System--cont.

J. Acetylene working pressure gauge

K. Acetylene regulator

L. Acetylene regulator adjusting screw

M. Acetylene hose

N. Oxygen hose

O. Acetylene torch valve

P. Oxygen torch valve

Q. Torch

R. Welding tip

S. Acetylene cylinder

T. Oxygen cylinder

Oxyfuel System Components

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Oxygen Cylinder

What are the characteristics of an oxygen cylinder?

What are the primary hazards in the use of an oxygen cylinder?

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Oxygen Cylinder Valve

What is different about an oxygen valve compared to a water faucet?

How far should it be open when in use?

Oxygen Valve—Parts

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A. Upper seat

B. Lower seat

C. Safety nut

D. Safety disc

E. Cylinder connection

F. Regulator connection

G. Stem nut

H. Valve stem

I. Hand wheel

Oxygen Valve—cont.

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OpenClosed

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Acetylene Cylinder

What are the characteristics of an acetylene cylinder?

What are the primary hazards in the use of an acetylene cylinder?

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Acetylene Valve

What is different about an acetylene cylinder valve compared to an oxygen cylinder valve?

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LPG Gas Cylinders

How is an LPG cylinder different from an oxygen or acetylene cylinder?

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Regulators

What is the function of an oxyfuel regulator?

Regulator parts:

A.Pressure adjusting screw

B.Bonnet

C.Needle valve

D.Hose connection

E.Cylinder connection

F.Needle valve seat

G.Diaphragm

H.Spring

I.Nylon thread insert

How does it work?

Regulators—cont.

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Do all regulators have a pressure adjusting screw?

No. Some are fixed pressure.

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Regulators—cont.

What hazards are associated with oxyfuel regulators?

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Regulator Creep

What is regulator creep?

What can cause regulator creep?

What hazards are associated with regulator creep?

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Gauge Not Returning To Zero

Why would a gauge not return to zero?

What can cause this condition?

What are the possible outcomes of using a regulator that has a gauge that does not return to zero?

Backfires and Flashbacks

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Backfire

What is a backfire when using an oxyfuel torch?

How do you know when a backfire has occurred?

What should you do when one occurs?

What are the hazards associated with a backfire?

What is the primary cause of backfires?

What What is the risk of a backfire?

Flashback

A. What is a flashback when using an oxyfuel torch?

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B. How do you know when one has occurred?

C. What causes flashbacks?

D. What should you do if you suspect one has occurred?

E. What is the potential hazard of a flashback?

F. What is the risk of a flashback?

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Check Valves and Flashback Arrestors

What is the purpose of a check valve?

What does a flashback arrestor do?

Working Pressure

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Working Pressure

Oxygen and fuel gas working pressure should be set according to manufactures recommendations for the job being performed.

What factors influence the ideal working pressure?

Can excessive working pressure cause problems when welding?

Yes. What are they?

Can insufficient working pressure cause problems when welding?

Yes. What are they?

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Oxyfuel Torch

What is the purpose of the oxyfuel torch?

Important facts when using oxyfuel torch.

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Hoses and Connections

Are there any unique characteristics of oxyfuel hoses?

Are there any unique characteristics of oxyfuel hose connections?

How should hoses be treated?

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PPE

What are the three primary hazards associated with oxyfuel systems and how are they managed?

Hazard ManagementHarmful light Shaded goggles

or face shieldHot metal Pliers and glovesFlying molten droplets Welding apparel

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Setting Up Oxyfuel System

Extinguish all open flames and stop processes that produce sparks.

Steps (assuming new system)

1. Secure cylinders

2. Remove caps

3. Crack cylinder valves

4. Connect regulators

5. Open cylinder valves

6. Connect hoses to cylinders

7. Connect hoses to torch body

8. Connect welding tip to torch body

9. Set working pressures

10.Check system for leaks.

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Shutting Down System

Close cylinder valves

Open torch valves– Leave open until regulator gauges read zero.

– Some sources recommend doing fuel first and oxygen last.

Close torch valves

Release tension on regulator adjusting screw.

Roll up hoses and place torch in a safe position.

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Questions?