Introduction to Submerged Arc Welding

2.  Introduction to Submerged arc welding [SAW]
 Process of SAW
 Types of SAW
 Advantages of SAW
 Limitations of SAW
 Applications of SAW

3.  Submerged arc welding (SAW) is
a method in which the heat
required to fuse the metal is
generated by an arc formed by an
electric current passing between
the electrode and the workpiece.
 There is no visible arc and no
sparks, spatter or fume. The
electrode may be a solid or cored
wire or a strip.
 SAW is normally a mechanised
process.

4.  The submerged arc welding flux feeds through the hopper tube
and continuously distributes itself over the seam a short distance
ahead of the welding zone.
 The wire feed mechanism begins to feed the welding into the
joint at a controlled rate.
 An electric arc is established as the current flows between the
electrode and the work.
 The carriage is started(manually or automatically) to travel
along the seam.

5.  Current: the total welding current can range between
100 and 3600 amps.
 Wires in one molten pool: from 1 to 6.
 Voltage: 20-50 volts.
 Speed: 30-350 cm/min.
 Deposition rate: 2-100 kg/hr.

6. SAW can be employed in five ways
Single Wire
• Single wire welding is
the most widely used
SAW method.
• DC power source is
used.
• The solid or cored wires
of diameter 2.0-4.0 mm
are used.
•A
small
diameter
produces
a
higher
deposition at the same
rate.

7. SAW can be employed in five ways
Twin Wire
• For twin wire welding,
two wires are connected
to the same power source.
• DC power source is used
• It offers up to 30%
higher deposition rates
and can be used at higher
currents and speeds.
• Very
high
welding
speeds can be achieved in
fillet welding.

8. SAW can be employed in five ways
Tandem
•In
tandem
sub-arc
welding each of the two
wires is connected to its
own power source and
fed simultaneously by its
own feed unit.
• Both AC and DC source
can be used.
• The wires are normally
large diameter (3.0-5.0
mm) and deposition rates
are about twice that of
single-wire welding.

9. SAW can be employed in five ways
Tandem Twin
•The ESAB tandem-twin
process involves two twin
wire heads placed in
sequence.
•Both AC and DC source
can be used.
•With the use of 4x2.5
mm
diameter,
wires
deposition rates of up to
38 kg/h can be achieved.

10. SAW can be employed in five ways
Multi wire
•Up to six wires can be
used together, each with
their own power source.
• The lead wire is usually
DC+ polarity with the
trailing wires being AC.
• Speeds of up to 2.5
m/min can be achieved
giving
a
maximum
deposition rate of 90 kg/h.
• This
technique
is
particularly suitable for
longitudinal pipe welding.

11.  High quality
 Little risk of undercut and porosity
 No spatter
 Very little risk of lack of fusion due to deep and safe
penetration
 High deposition rate
High thermal efficiency
 No radiation
 High welding speeds are possible

12.  Precise joint preparation required
 No observation of arc and process during welding is possible
 High operational effort
 It can not be used for plates less than 5mm thickness
 Flux is subjected to contamination and adsorbtion of
moisture.
 Solidification cracking.
 Irregular wire feed.

13. This welding method can be used for:-
 Fabrication of Boiler Pressure Vessel.
 Railroad tank cars.
 Structural shapes and cylinders.
 Circular welds.
 Beam Production.
 Ship Building.
 Circumferential welding in wind tower fabrication.
 Longitudinal pipe welding.