Oxy/fuel gas welding and cutting equipment. Safety Presentation Oxy/fuel gas welding and cutting equipment.

DON’T LET THIS HAPPEN TO YOU !

Combustion Theory

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

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

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 – Adequate risk assessment – Never clean clothes with oxygen -- Never hang coats or clothing on cylinders

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

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

Acetylene Cylinder Low Pressure – 1724 kpa @ 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 Fusible Plug Monolithic Porous Filler Material

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

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

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

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

Regulators Oxygen Acetylene LPG Argon Nitrogen CO2 Hydrogen

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

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

Hoses Are colour coded----Blue---Oxygen Orange—LPG Red----Acetylene Orange—LPG 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

Attachments & mixers

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

Check Valves CORRECT FLOW REVERSE FLOW

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

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.

What’s inside a flashback arrestor ?

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

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

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).

Cutting Torches

Welding Flame Types Carburizing Flame Neutral Flame Oxidizing Flame

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

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

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.

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

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

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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