2 gas welding
TRANSCRIPT
-
7/25/2019 2 Gas Welding
1/17
Gas Welding (Oxy-acetylene)
A number of welding processes use a flameproduced by burning a mixture offuel gasand
oxygen. The gas usually used isAcetylenebut
other gases are also used.eparate cylinders and
a hose pipe from each
cylinder transports the
gases to a torch.
Gas and fuel mix in
the torch burns !
"#$$%&.
-
7/25/2019 2 Gas Welding
2/17
Gas Welding
-
7/25/2019 2 Gas Welding
3/17
-
7/25/2019 2 Gas Welding
4/17
-
7/25/2019 2 Gas Welding
5/17
'uring the welding heat from the flame is
concentrated on the oint edges until the
metal melts and starts to flow. When the
molten metal from both sides melts it starts to
fuse when the metal cools down the two parts
becomePermanentlyoined
AdditionalFiller
Metalis fed in by
hand into the weld
pool at regularinter*als where it
becomes molten
and oins with the
parent metal.
-
7/25/2019 2 Gas Welding
6/17
Oxy-acetylene
fames
-
7/25/2019 2 Gas Welding
7/17
Carburising Neutral Oxidising
The Oxy-acetylene welding +lame
-
7/25/2019 2 Gas Welding
8/17
Equipment used in Oxy-
Acetylene welding
The oxygen and acetylene hose pipes
Gases used
Gas pressure ,egulators
+lashbac arrestor
Welding torchWelding no//le
+iller rods and fluxes
-
7/25/2019 2 Gas Welding
9/17
The oxygen and acetylene hose pipes
,einforced rubber hoses.
Acetylene hose has left hand thread couplings and colour
coded red.
Oxygen hose has right handed thread couplings and colour
coded blue
-
7/25/2019 2 Gas Welding
10/17
Gases used O0 and &010
Oxygen extracted from air and compressed into cylinders at high
pressure. &ylinder is blac.
Acetylene (&010) is a fuel gas. &annot be compressed directly as
explodes at high pressures.
&ylinders are paced with porous material which is filled withacetone.
Acetone absorbs acetylene. &ylinder colour coded maroon
-
7/25/2019 2 Gas Welding
11/17
Gas 2ressure ,egulators
One gauge indicates the pressure of the cylinder and the
other indicates the pressure in the supply pipe to the torch.
-
7/25/2019 2 Gas Welding
12/17
Welding torch
Oxygen and acetylene are deli*ered to the torch by separate hoses.
3ach gas is controlled by a *al*e on the torch.
The two gases mix in the torch and after they are ignited burn at
the no//le.
4ixer 5eedle *al*es
-
7/25/2019 2 Gas Welding
13/17
+lashbac Arrestors
These are positioned on both the fuel gas and oxygen
supply between the hose and the regulator. Their purpose
is to pre*ent the return of a flame through the hose into
the regulator.
-
7/25/2019 2 Gas Welding
14/17
+iller ,ods and fluxes
+iller rods are used when additional filler metal is re6uired in the
weld area they come in different diameters.
+luxes protect the weld pool from contamination by oxygen andnitrogen they are normally in paste form placed on a heated
filler rod before welding begins
-
7/25/2019 2 Gas Welding
15/17
'angers of OAW
The combination of acetylene and oxygen is highly
flammable and the en*ironment in which OAW is performed
is therefore ha/ardous.
ome of the dangers relate specifically to the acetylene.
1) Pure C2H2 is a clrless! drless gas"
olution7 +or safety reasons commercial acetylene isprocessed to ha*e a characteristic garlic odor.
-
7/25/2019 2 Gas Welding
16/17
'angers of OAW
2) One # t$e p$ysical limitatins # t$e gas is t$at it is
unstable at pressures muc$ ab%e 1 atm &'"1 (Pa).
lutin7 Accordingly acetylene storage cylinders are pacedwith a porous filler material (such as asbestos balsa wood and
other materials) saturated with acetone (&1"&O&1").
Acetylene dissol*es in li6uid acetone8 in fact acetone dissol*es
about 09 times its own *olume of acetylene thus pro*iding arelati*ely safe means of storing this welding gas.
-
7/25/2019 2 Gas Welding
17/17
2lease study the
ad*antages and
disad*antages from*ideo