Oxyfuel Gas Welding Cutting Welding n process in

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Oxyfuel Gas Welding & Cutting

Oxyfuel Gas Welding & Cutting

Welding n process in which metals are joined by heating them to the melting

Welding n process in which metals are joined by heating them to the melting point and allowg the molten portions to flow together to form one

Processes confused with oxyfuel gas welding are: soldering - two metals not melted are

Processes confused with oxyfuel gas welding are: soldering - two metals not melted are joined by a third metal with a melting point below 840 deg F. n brazing - temps above 840 deg F. n

Torch n allows for controlling and mixing gases

Torch n allows for controlling and mixing gases

Torch tip cleaner

Torch tip cleaner

Fuel Gasses used with O 2 acetylene n hydrogen n natural gas - (high

Fuel Gasses used with O 2 acetylene n hydrogen n natural gas - (high hydrogen concentration – brittle welds) n propane n mapp – (methylacetylenepropadiene) (no special containers) n

Acetylene (most common) most unstable n 1/7 rule of contents - 1/7 on contents

Acetylene (most common) most unstable n 1/7 rule of contents - 1/7 on contents per hour n asbestus and porous concrete or balsa core filled with acetone liquid n

Acetylene (Cont. ) unstable acetylene is suspended in core n keep upright or acetone

Acetylene (Cont. ) unstable acetylene is suspended in core n keep upright or acetone leaks out of core into cylinder n • open valve - get acetone n takes 7 hours for acetone to migrate back into core

Oxyfuel Flames n Carburizing - too much fuel gas adds carbon to the metal

Oxyfuel Flames n Carburizing - too much fuel gas adds carbon to the metal being welded

n Oxidizing - too much oxygen - burns the metal

n Oxidizing - too much oxygen - burns the metal

n Neutral - the oxygen and fuel gases combine • oxygen burns up the

n Neutral - the oxygen and fuel gases combine • oxygen burns up the carbon and the hydrogen in the fuel gas then releases only heat and harmless gases • flame temp is 5589 deg F.

Temps required to melt various metals

Temps required to melt various metals

Quantity of heat determined by: type of gas n number of cubit feet per

Quantity of heat determined by: type of gas n number of cubit feet per hour of gas burned n for more heat - larger orifice in torch tip along with more pressure to feed gas through n

Safety

Safety

Clothing and Eye protection

Clothing and Eye protection

Acetylene more dangerous than oxygen? Makes things burn faster n oxygen must be consumed

Acetylene more dangerous than oxygen? Makes things burn faster n oxygen must be consumed even under water n no O 2 in air tools n no blowing off clothes n 20 lb propane grill tanks in car trunks n

Oxygen cylinders

Oxygen cylinders

Cylinder safety read label - different colors for same gas n orange - O

Cylinder safety read label - different colors for same gas n orange - O 2 or helium n red - O 2 or hydrogen n blue - O 2 or nitrous oxide n green n

Handling cylinders caps on when moving n secure to truck or wall n keep

Handling cylinders caps on when moving n secure to truck or wall n keep upright n

Preparing cylinders and hoses cylinder valve should be opened slightly to blow out dirt

Preparing cylinders and hoses cylinder valve should be opened slightly to blow out dirt n high pressure valves - open all the way n gas valves - open 1/4 to 1/2 turn n

Preparing (Cont. ) n hose and cylinder valve threads • fuel gas - left

Preparing (Cont. ) n hose and cylinder valve threads • fuel gas - left hand • oxygen - right hand after assembly - test for leaks with soap suds n flash arrestor - stops reverse flow of gases and fire n • put at tank for torch?

Torch position, angle, motion

Torch position, angle, motion

Joints

Joints

Plug Weld

Plug Weld

Use additional filler rod where joint design and strength require

Use additional filler rod where joint design and strength require

Positioning Tacking n Shrinkage n Wedge n

Positioning Tacking n Shrinkage n Wedge n

Turning on and shutting down the oxy acetylene welding outfit

Turning on and shutting down the oxy acetylene welding outfit

Cutting

Cutting

oxyfuel gas flame is used to heat the metal and an oxygen jet is

oxyfuel gas flame is used to heat the metal and an oxygen jet is used to perform the cutting

steel is combustible if sufficiently heated

steel is combustible if sufficiently heated

burning metal helps to maintain the high temp

burning metal helps to maintain the high temp

Process same flame as for welding n preheat flame about 1/16 to 1/8” from

Process same flame as for welding n preheat flame about 1/16 to 1/8” from surface n heat a spot on steel to cherry red (1300 to 1400 deg F) n oxygen jet is turned on n torch moved n preheat flame kept operating during cutting action n

Cutting torch outfit differs from welding only in torch - separate passage for oxygen

Cutting torch outfit differs from welding only in torch - separate passage for oxygen jet - center orifice n possibly a higher pressure O 2 regulator n oxygen cutting lever to control cutting operation n

indicator of a good cut no slag at bottom of cut n no bell-mouthed

indicator of a good cut no slag at bottom of cut n no bell-mouthed kurf n

Alignment of torch tip orifices with the kerf • one orifice should proceed and

Alignment of torch tip orifices with the kerf • one orifice should proceed and one should follow the cut

Usually no torch motion used - sometimes oscillating

Usually no torch motion used - sometimes oscillating

torch movement should be away from operator so kerf can be seen

torch movement should be away from operator so kerf can be seen

Speed

Speed

safety leggings n safety boots with high tops n no cuffs n

safety leggings n safety boots with high tops n no cuffs n

Cutting thin steel under 1/2” n smallest cutting tip available n point tip in

Cutting thin steel under 1/2” n smallest cutting tip available n point tip in direction the torch is traveling (15 -20 deg) from metal n

Metal over 1/2” thick n Tip perpendicular

Metal over 1/2” thick n Tip perpendicular

Starting a cut - thicker material n cuts normally started at the edge of

Starting a cut - thicker material n cuts normally started at the edge of the work

Pipe small diameter - hold tip almost tangent to pipe n large diameter (over

Pipe small diameter - hold tip almost tangent to pipe n large diameter (over 4”) tip perpendicular n

Beveled edge on plate

Beveled edge on plate

Beveled end on pipe

Beveled end on pipe

Turning on and shutting down the oxy acetylene welding outfit

Turning on and shutting down the oxy acetylene welding outfit