Oxy/fuel gas welding and cutting equipment.

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Safety Presentation

• Oxy/fuel gas welding and cutting equipment.

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DONT LET THIS HAPPEN TO YOU !
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Combustion Theory
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HAZARDS!

• 1. Pressure
• 2. Flammability
• 3. Toxicity
• 4. Oxygen Compatibility
• 5. Oxygen Deficiency / Enrichment
• 6. Weight Size

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Hazards

• . Damage reduces cylinder safe working pressure.
• falling over
• corrosion
• bumps, impacts
• Excessive heat increases pressure in cylinder
  past safe working pressure.
• Prevention
• Pressure safety devices in cylinder
• Care when using, transporting storing
  cylinders

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Hazards

• Oxygen Compatibility
• material that will react with oxygen
• oil, dust, grit
• Safeguards
• never use oil grease on cylinders
• never use cylinders with dirty valves
• Oxygen Deficiency/Enrichment
• Enrichment - oxygen release
• Deficiency - oxygen replaced by asphyxiants
• Safeguards
• Adequate risk assessment
• Never clean clothes with oxygen
• -- Never hang coats or clothing on cylinders

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Oxygen cylinder
High Pressure Cylinder 20,000 kpa or
higher Hollow, Seamless Steel Construction Do Not
Abuse Cylinder Never Use For Other Than Intended
Use Report Any Damage to Supplier
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Using Oxygen

• Open valves slowly
• Keep clean from grease or oil
• Do not use teflon thread tape
• Use in upright position
• Keep cylinder secured properly
• Beware of high pressure

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Acetylene Cylinder

• Low Pressure 1724 kpa _at_ 21.1o C
• Thin Walls, Welded And Easily Damaged
• Do Not Abuse Can explode if damaged
• Never Use A Damaged Cylinder
• Report Damages To Supplier
• Do Not Attempt To Repair Leaks
• Move Leaking Cylinder Outside If Permitted
• Must be stored and transported in upright
  position

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Acetylene Fires

• Most Fires Start In Valve Area Check for Leaks
• Fusible Metal Plugs Melt At 100o C
• Flames 5 x 3
• Very Difficult To Extinguish
• Evacuate Area
• Call Fire Department

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Using Acetylene

• Flammable Keep Away From Sources of Ignition or
  Heat
• Shock Sensitive May Decompose Violently
• Limited Withdrawal Rate 1/7th Rule
• Asphyxiation
• 150 KPA Maximum Use Pressure
• Do Not Use Copper Piping

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Liquid Petroleum Gas LPG

• Propane, Propylene Mapp, Etc.
• Liquid Under Pressure
• Heavier Than Air
• Not Shock Sensitive
• Can Be Used Up To Full Cylinder Pressure
• Liquid expands 270 times in volume when released
  to atmosphere

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LPG Cylinder

• Hollow Welded Thin Wall Cylinder
• Vapor Space Above Liquid
• Use Only While Standing Up
• Low Pressure Less Than 500 PSIG, 3400 kpa
• Has Fast Acting Valve
• Open ½ to 1 Full Turn
• Valve Safety Relieves and Resets
• Never Use A Damaged Cylinder

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Regulators

• Oxygen
• Acetylene
• LPG
• Argon
• Nitrogen
• CO2
• Hydrogen

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Regulators
High Pressure Dial Gauge Low Pressure Dial
Gauge Body Bonnet Adjustment Knob Heavy Duty
Adjusting Spring Diaphragm Encapsulated Seat
Assembly Inlet Spigot Inlet Filter Outlet
Connector
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Regulators

• Regulators are a pressure vessel
• Fitted with high and low pressure gauges
• Reduce high pressure to a useable low pressure
• Are fitted with safety devices
• Are colour coded
• Must be marked with Aust Standards AS4267
• Must have maximum working pressure
• Are designed for specific gases

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Hoses

• Are colour coded----Blue---Oxygen
• Red----Acetylene
• OrangeLPG
• Must comply with Aust Standards AS1335
• Maximum length is 15 meters
• Maximum working pressure is 1200 kpa
• Are sized to suit flow requirements of equipment
  being used

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Attachments mixers
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Safety Devices

• CHECK VALVES
• Are the basic safety device
• Prevents flash back accidents caused by reverse
  flow
• -Flashbacks can cause the most serious
  accidents
• Check valves can fail because of dirt or other
  contamination
• -Keep equipment clean
• -Check them periodically

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Check Valves
CORRECT FLOW
REVERSE FLOW
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Flashback Arrestors

• Flashback arrestors are the ultimate safety
  device
• Prevent flashback travelling back to fuel or
  oxygen source
• Come in different sizes to suit flow requirements
  of equipment being used
• NB A flashback arrestor does not stop a
  flashback from occurring , they only stop it
  travelling back to the fuel source

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What is a flashback ?

• A flashback occurs when a mixture of oxygen
  fuel gas is ignited upstream of tip
• An oxygen and acetylene flashback travels at 13.1
  meters per second
• 80 of flashbacks are caused by human error
• Causes can be , wrong gas pressures , incorrect
  purging , blocked or wrong tip , wrong sized hose
  or flash arrestor.

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Whats inside a flashback arrestor ?
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Where do I fit flash arrestors ?

• As close to the mixing point as possible
• Minimum protection at hand piece only
• Maximum protection at hand piece and regulator
• Be care full , over protection can restrict flow
  , and actually cause a flash back
• Check the gas flow requirements of the equipment
  before selecting the arrestors

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What should I see on an arrestor ?

• Brand and type
• Flow directional arrow
• Date installed or last tested
• Australian Standards AS4603
• Year of manufacture
• Maximum working pressure

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Leak Testing Procedure

• Turn off hand piece.
• Turn on cylinder valve.
• Adjust regulator to normal working pressure and
  pressurize hose.
• Note working pressure.
• Turn off cylinder valve.
• If pressure drops obviously over two minutes then
  there is a leak.
• If the leak is not obvious, find it using
  Nuprosnoop (not soapy water as it may contain
  oily residue).

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Cutting Torches
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Welding Flame Types

• Carburizing Flame
• Neutral Flame
• Oxidizing Flame

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Lighting Equal Pressure LPG Torches

• Open Torch Valves 1/8 to ¼ Turn
• Ignite Fuel Gas With Approved Igniter and Adjust
  Flame
• Introduce Oxygen And Adjust To The Desired Flame
• It is Permissible To Light The Flame With Both
  Gases Flowing , sometimes necessary
• Adjusting For large or Heating Tips , increase
  fuel then oxy in successive steps

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Lighting An Oxy/Acetylene Torch

• Slightly Open Acetylene Valve And Light With An
  Approved Device
• Root Flame and Clear Smoke
• Open Oxygen Valve And Set Flame To Neutral
• Sharp, Defined Inner Cone
• Never Light Torch With Both Oxygen And Acetylene
  Flowing

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Lighting Low Pressure Injector Torches

• It is permissible to light torch with both gases
  flowing.
• Use special purge sequence to clear system of
  mixed gases.
• Open fuel gas valve ½ to ¾ turn.
• Open oxygen valve slightly 1/8 to 1/4 turn.
• Adjust to desired flame.
• Adjusting for large or heating tips , increase
  fuel then oxy in successive steps.

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Turning Off An Oxy/Acetylene Torch

• Proper Sequence Checks Integrity of Torch Valves
• Close Oxygen Valve First
• Close Acetylene Valve Second
• If Acetylene Valve is Leaking a Small Flame Will
  Continue Burning
• If Oxygen Valve is Leaking, Torch Will Pop as
  Acetylene Valve Is Closed
• If Either Valve Is Leaking, Repair Before Further
  Use

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Turning Off Alternate Fuel Torches

• Close Fuel Gas Valve First
• Close Oxygen Valve Second
• This Sequence Can Prevent The Operator From Being
  Burned
• If Fuel Pressure is Great Enough - Check Valves
  At Initial Light Up By Turning Oxygen Off First

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Shutting Down An Oxy/Fuel Torch

• Overnight Or For An Extended Period of Time
• Turn Off Torch
• Close Cylinder Valves
• Open Then Close Each Torch Valve Independently To
  Bleed Pressure
• Back Regulator Adjusting Screw Out Until Loose
• Store Hose and Equipment In a Clean Area Away
  From Potential Damage

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THE END