Advanced Welding Processes: Technologies and Process Control

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Advanced welding processes
9.9 Rotating tip techniques.
system have therefore been developed. These devices use bending rollers to
introduce a wave-like or spiral deformation into the wire in order to cause
controlled oscillation of the arc. Although the mechanism required to produce
the deformation may be complex, the part of the torch that enters the joint is
compact and satisfactory joints can be made in gap widths down to around
9 mm.
Modification of process operating mode. Many of the systems now available
use the pulsed transfer GMAW techniques described in Chapter 7 to improve
process control and limit spatter formation.
Applications of narrow-gap GMAW
The narrow-gap GMAW process has been used for downhand welding of
circumferential joints in pipe and shafts with the workpiece rotated under the
welding head. The GMAW process may also be applied to positional (5G)
welding of pipe as described in Section 3.2.1 and has also been used [188]
for welding horizontal joints in tubular structures and building columns as
shown in Fig. 9.10, particularly in Japan.
In the offshore industry, interest has been shown in the application of the
process to horizontal welds (2G) in vertical pipe for ‘J’ laying of transmission
pipelines at sea. Although this has been found to be feasible, it requires very
careful control of the process parameters and gap width to ensure that consistent
bead profile and fusion characteristics are maintained.