Oxy-Acetylene Oxy-Acetylene Safety AwarenessSafety Awareness

Presents

Revised 6/01

Just a noteJust a note• This program is This program is

informational only and informational only and does not certify or does not certify or qualify any persons in qualify any persons in the use of Oxy-the use of Oxy-Acetylene burning or Acetylene burning or welding.welding.

• For the proper use of For the proper use of your equipment, your equipment, please contact your please contact your supplier or supplier or manufacturermanufacturer

Something to think Something to think on……on……

Every time you use the Every time you use the oxy-acetylene equipment , oxy-acetylene equipment , if certain safety guidelinesif certain safety guidelinesare not followed, it would are not followed, it would be the same as handlingbe the same as handlinglive explosives ready to go live explosives ready to go off…….off…….

Now let’s talk about the gases

What is Oxygen What is Oxygen • Remember, oxygen is not airRemember, oxygen is not air

• There is approximately 21% oxygen in normal airThere is approximately 21% oxygen in normal air

• Oxygen is found naturally in the atmosphereOxygen is found naturally in the atmosphere

• It is produced industrially by distilling air below it’s freezing pointIt is produced industrially by distilling air below it’s freezing point• Pure oxygen does not burn or explode Pure oxygen does not burn or explode

• Oxygen is an Oxygen is an “accelerant”“accelerant” , it causes every thing it comes in contact with to burn , it causes every thing it comes in contact with to burn hotter and fasterhotter and faster

• Air has a vapor density of 1.000, Oxygen is heavier than air (1.105) This means if a Air has a vapor density of 1.000, Oxygen is heavier than air (1.105) This means if a oxygen bottle is leaking, the gas will settle in low areas before diffusing back into oxygen bottle is leaking, the gas will settle in low areas before diffusing back into the atmosphere.the atmosphere.

• 30% oxygen in the atmosphere will cause things to burn or explode 8 times faster30% oxygen in the atmosphere will cause things to burn or explode 8 times faster

• in pneumatic tools-in pneumatic tools- the oil and the gas pressure friction can cause a fire or explosion the oil and the gas pressure friction can cause a fire or explosion

• in oil pre-heating burners-in oil pre-heating burners- these burners are set to burn with 21% oxygen to air ratio these burners are set to burn with 21% oxygen to air ratio

• to start internal combustion engines-to start internal combustion engines- gasoline is flammable enough with 21% oxygen gasoline is flammable enough with 21% oxygen availableavailable

• to blow out pipelines-to blow out pipelines- Leftover flammable or combustible vapors may still be present to Leftover flammable or combustible vapors may still be present to cause an explosioncause an explosion

• to dust off clothing or work area-to dust off clothing or work area- the oxygen will remain present in the cloth fibers the oxygen will remain present in the cloth fibers causing them to be more flammablecausing them to be more flammable

• to create pressureto create pressure

• for ventilationfor ventilation

• Remember, oxygen is not airRemember, oxygen is not air

Never use oxygen……….Never use oxygen……….

How are oxygen bottles constructedHow are oxygen bottles constructed

• Usually of steel constructionUsually of steel construction• 244 cu. ft is standard size (K size)244 cu. ft is standard size (K size)• 2000 to 2600 psi2000 to 2600 psi• Hollow in constructionHollow in construction• An electric arc can cause an oxygen bottle to An electric arc can cause an oxygen bottle to

explode (the carbon in the steel will atomize into a explode (the carbon in the steel will atomize into a fuel)fuel)

• The orifice at the top of the bottle is the diameter of The orifice at the top of the bottle is the diameter of the lead in a pencil ( if the bottle top is damaged, the lead in a pencil ( if the bottle top is damaged, the bottle can become projectile causing injury or the bottle can become projectile causing injury or property damageproperty damage

• Never allow a tank to go empty (this may allow Never allow a tank to go empty (this may allow acetylene to travel into the oxygen lines or bottleacetylene to travel into the oxygen lines or bottle

• Keep free from oil and greaseKeep free from oil and grease

What is acetyleneWhat is acetylene• Acetylene is a compound of Hydrogen and Carbon Acetylene is a compound of Hydrogen and Carbon

(C(C22HH22) a member of the hydrocarbon gases) a member of the hydrocarbon gases• Explosive range is 3.0 to 93%Explosive range is 3.0 to 93%• Needs only 10% of oxygen to igniteNeeds only 10% of oxygen to ignite• Produced when calcium carbide is mixed with waterProduced when calcium carbide is mixed with water• It is an unstable gas, will violently decompose when It is an unstable gas, will violently decompose when

in a pure state above 15 psiin a pure state above 15 psi• Has a burning temperature of 4,600Has a burning temperature of 4,600o o F, 5,700F, 5,700o o F when F when

burned with oxygenburned with oxygen• Auto-ignition temperature is 763Auto-ignition temperature is 763oo - 824 - 824oo F, this means F, this means

if acetylene reaches 30 psi in a free state, it can if acetylene reaches 30 psi in a free state, it can explode by itself without a spark or flame being explode by itself without a spark or flame being presentpresent

• Remember, acetylene is a very dangerousRemember, acetylene is a very dangerous gas

Why doesn’t acetylene explode in the bottleWhy doesn’t acetylene explode in the bottle

• Acetylene Acetylene burns in air readilyburns in air readily, and is most safely hand- , and is most safely hand- led/stored in cylinders filled with crushed firebrick wet led/stored in cylinders filled with crushed firebrick wet with acetone. with acetone.

• Acetylene happens to dissolve readily into acetone, and Acetylene happens to dissolve readily into acetone, and the dissolved gas is no longer in contact with gaseous the dissolved gas is no longer in contact with gaseous OO22 (which does not tend to dissolve in acetone) and (which does not tend to dissolve in acetone) and therefore is not as prone to therefore is not as prone to decomposition by Odecomposition by O22. .

• The firebrick also helps by minimizing the free volume The firebrick also helps by minimizing the free volume of the cylinder, cooling and controlling any thermal of the cylinder, cooling and controlling any thermal decomposition before it gets out of control (each decomposition before it gets out of control (each decomposition of acetylene gives off heat). decomposition of acetylene gives off heat).

• Acetylene cylinders must, therefore, be refilled only by authorized Acetylene cylinders must, therefore, be refilled only by authorized gas distributors. Acetylene cylinders must never be transfilled.gas distributors. Acetylene cylinders must never be transfilled.

How are acetylene bottles constructedHow are acetylene bottles constructed

• Usually are steel construction• Filled with a porous material to allow the acetone to dissolve the

acetylene, which makes it stable• Porous filler(8-10%), Acetone(42%)• Acetylene gas(36%), • Reserve volume-70o F(10-12%)• Never allow a tank to go empty

– Oxygen may back pressure into the bottle• Comes in various sizes• Must always be stored upright

– This prevents the acetone and acetylenefrom separating

• Should not be stored below freezing– Acetone may come out instead of acetylene

and may clog the regulators

Care & maintenance of the Gas RegulatorsCare & maintenance of the Gas Regulators

The internal working parts of the regulator are precision units. Only The internal working parts of the regulator are precision units. Only qualified technicians should clean or repair a regulatorqualified technicians should clean or repair a regulator

The The Inlet ConnectionsInlet ConnectionsOxygen are right Oxygen are right hand hand thread/Acetylene thread/Acetylene are left hand are left hand threadthreadKeep free of oil, Keep free of oil, grease, & dirt grease, & dirt

The Pressure adjusting screwThe Pressure adjusting screw

Turning clockwise allows the gas Turning clockwise allows the gas allows to flowallows to flow

Turning counterclockwise reduces or Turning counterclockwise reduces or stops the gas flow stops the gas flow

The High pressure The High pressure gaugegauge

Indicates the Indicates the pressure from pressure from tanktank

The Low The Low pressure pressure gaugegauge

Indicates Indicates the the delivery delivery pressure pressure to the to the hoses & hoses & torchtorch

Some more info on regulatorsWarning -Always keep the regulator free of oil, grease and other

flammable substances

Never use oil or grease on the regulator, cylinder or manifold connection

DO NOT change the inlet connection on a regulator in an attempt to use the regulator for a different gas service

Never stand in front or behind a Never stand in front or behind a regulator when opening the cylinder regulator when opening the cylinder valvevalve

Backfires and flashbacks

• Backfires occur when the torch flame burns back into the torch tip and is extinguished with a loud pop.

• They occur either because the torch tip touched the work or because of insufficient gas pressure.

• They are generally harmless. However, flashbacks are more serious when the flame front does not extinguish, but burns back sometimes beyond the mixing chamber, through the hoses, and even into regulator and supply.

• A common inside diameter of oxy-fuel gas hose is 1/4 inch. If you calculate the volume of 100 feet of hose with an inside diameter of 1/4 inch, this means, should oxygen enter the fuel gas hose or should fuel gas enter the oxygen hose, a mixed gas explosion with the force potential of 20 sticks of dynamite could occur.

Check valves

Flow of gas keeps valve open

•The purpose of an internal check valve is to reduce the The purpose of an internal check valve is to reduce the possibility of reverse flow gas. possibility of reverse flow gas. •It is not intended to act as a fire stop! It is not intended to act as a fire stop! •Ensure that the internal check valves are working properly by Ensure that the internal check valves are working properly by testing at least every six months, more often if the hoses testing at least every six months, more often if the hoses are frequently removed from the torch.are frequently removed from the torch.

Spring activated

Gas flow Once flow pressure decreases, valve will closes preventing back flow of gas

Flashback arrestorsFlashback arrestors

Flame path is extinguished by meshed material inside

•Flashback arrestors are designed to prevent a Flashback arrestors are designed to prevent a flashback from reaching upstream equipment.flashback from reaching upstream equipment. •They offer added safety and often include reverse They offer added safety and often include reverse flow check valves in a single unitflow check valves in a single unit

Torch handle

The HosesThe Hoses

• The hoses are usually color coded, but not always – Oxygen(green) – Acetylene(red)– Be careful not to use other hoses, such as air lines, LP gas, etc.

• They are neoprene over braided inner section– Be careful around sharp objects, they can be cut very easily

• They are constructed of flame retardant materials, but will burn if there is a flashback or exposed to sustained heat

• Hoses are graded – Make sure you are using the right hose for the right gas

More hose stuff

• Keep welding hoses clear of any failing metal, slag or sparks.

• Never allow hoses to become coated with oil, grease or dirt. Such coatings could conceal damaged areas.

• Examine the hoses before attaching to welding torch handle or regulators.

• If cuts, burns, worn areas or damaged fittings are found, replace the hose.

• Completely replace welding hose if it contains multiple splices or when cracks or severe wear is noticed.

Torch handleTorch handle

Torch headTorch head

Control valve & Control valve & body”Y”body”Y”

BarrelBarrel

Torch cutting attachmentTorch cutting attachment

There must always be two o-rings on the cone end. The absence or damage of either of these o-rings allows premixing and leaks of oxygen and fuel gases. This can lead to flashback within the torch handle.

 

•Always make sure your equipment is rated for the size tip you have selected.

•A tip with too much capacity for the equipment can starve or choke the tip. This causes overheating of the head and a flashback may result.

•A damaged seating surface on either the tip or the head can create a dangerous condition, resulting in a fire or flashback. This may damage the cutting attachment.

•If the seating surface of a tip becomes damaged, DO NOT use it. Discard the damaged tip.

•If the head requires repair, take the torch to a qualified repair technician.

What size cutting-tip do I need?

The type of torch you are using and the thickness of material being cut determine the proper size cutting-tip for use in oxy-acetylene flame cutting

What tip sizes do I use for oxy-acetylene welding and what pressures do I set on my regulators?

Tip sizes and gas regulator settings are dependent on the thickness of the material to be welded and the type torch being used

Always refer to the manufacture’s supplied cutting chart for the cutting tips you are using.

Remember, if you do not use the proper oxygen to acetylene ratio, you may cause an accident, at the very least you will waste gas, which costs $$$$.

• Never starve or choke a multi-flame heating Never starve or choke a multi-flame heating nozzle. This causes overheating of the head and nozzle. This causes overheating of the head and a flashback may result. a flashback may result.

• Should a flashback occur (flame disappears Should a flashback occur (flame disappears and/or a hissing sound is heard, the flame is and/or a hissing sound is heard, the flame is burning inside the nozzle), immediately turn off burning inside the nozzle), immediately turn off the oxygen valve on the torch handle. Then, turn the oxygen valve on the torch handle. Then, turn off the fuel valve. off the fuel valve.

• Allow the nozzle to cool before using. Allow the nozzle to cool before using. • If a flashback reoccurs, have the apparatus If a flashback reoccurs, have the apparatus

checked by a qualified technician before using checked by a qualified technician before using again.again.

Cutting Cutting tips and tips and nozzlesnozzles

Link to MSHA Regulations

Link to OSHA Requirements

Link to Pennsylvania State Requirements

Laws & Regulations Laws & Regulations

for for

Oxy-Acetylene UseOxy-Acetylene Use

                                                                                          

• Never allow oxygen to contact oil, grease or otherNever allow oxygen to contact oil, grease or other flammable substances flammable substances

• Never mix brandsNever mix brands

• Purge the lines before and after usagePurge the lines before and after usage

• Always wear protective clothing Always wear protective clothing

• Use proper eye protectionUse proper eye protection

Let’s Finish With Some Final General Safety Tips

                               

If flashback occurs, immediately turn off the OIf flashback occurs, immediately turn off the O22, then the , then the

acetylene, and allow unit to coolacetylene, and allow unit to cool

Always work in a well ventilated areaAlways work in a well ventilated area

Always light the acetylene firstAlways light the acetylene first

Oxygen cylinders must be opened the whole wayOxygen cylinders must be opened the whole way

Use an approved striker, never use matches or cigarette lighterUse an approved striker, never use matches or cigarette lighter

Use the proper regulator for each specific gasUse the proper regulator for each specific gas

Only qualified technicians should repair a regulatorOnly qualified technicians should repair a regulator

Keep regulators free of oil, grease and other flammable Keep regulators free of oil, grease and other flammable substancessubstances

General Safety Tips

Keep regulators free of oil, grease and other flammable Keep regulators free of oil, grease and other flammable substancessubstances

Check valves stop reverse gas flow, they do not act as a fire Check valves stop reverse gas flow, they do not act as a fire stopstop

Never starve a tip, this can cause a flashbackNever starve a tip, this can cause a flashback

Always keep cylinders in an upright positionAlways keep cylinders in an upright position

Never stand in front or behind a regulator when opening the Never stand in front or behind a regulator when opening the cylinder valvecylinder valve

Do not open acetylene valve more than 1 Do not open acetylene valve more than 1 11//2 2 turnsturns

Always make sure area is safe and flammable freeAlways make sure area is safe and flammable free

Safety Checklist for Getting Started What is the necessary safety equipment you need?

•Proper Eye protection

•Appropriate gloves

•Clothing free of grease & oil

•Clean work area

•Proper Task Training

•Fire extinguisher

Thank you and Thank you and Be CarefulBe Careful