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S. K. Das et al.
1.6.2 Circular Welding
Circular welding is mainly used for welding pipes. Although several configurations
have been devised, the basic fundamental of welding pipe is to make use of a precision
mandrel which can be inserted into the pipe pair, thus producing a seam over it. As
of now, there are primarily two setups for circular welding which are elaborated as
follows:
1.6.2.1 Customized Setup
Again as in case of linear welding, customized setups for pipe welding can be availed
from the major players in the field. These setups provide fast and precision solution
for pipe welding which can be beneficial to relevant fabricators.
1.6.2.2 Attaching a Rotary Mandrel Unit
An attachment consisting of a rotary turntable and mandrel can convert an existing
setup of linear welding to a circular welder. Sometimes, the attachment consists of
an expanding mandrel which can hold pipes with diameters varying within a certain
range. Generally, in these types of setups, the FSW tool remains fixed and the rotating
mandrel turns the pipes, thus producing the weld. It is obvious that the rotation of
the mandrel is precisely controlled. Figure 1.10 shows a typical FSW linear machine
fitted with a rotary mandrel for pipe welding.
1.6.2.3 Portable Setups—Larger Scale Welding
For carrying out welding of larger and longer pipes, portable welding machines are
also available. These setups have the advantage of being installed in the field. In these
setups, normally, the arrangement is such that the tool moves along the weld seam
producing the weld as it is difficult to rotate the huge and heavy mandrel supporting
the pipes.
1.6.2.4 Issue of the Presence of Ejection Hole
As already discussed (to be discussed previously), that FSW tool leaves an ejection
hole on the workpiece at the end of the weld. This may not be problem in case of jobs
requiring linear welding as some allowance for this can be incorporated in the job
and which can be later cut off. However, in case of circular welding which warrants a
sort of continuity, the presence of an ejection hole will make the joint vulnerable and
S. K. Das et al.
1.6.2 Circular Welding
Circular welding is mainly used for welding pipes. Although several configurations
have been devised, the basic fundamental of welding pipe is to make use of a precision
mandrel which can be inserted into the pipe pair, thus producing a seam over it. As
of now, there are primarily two setups for circular welding which are elaborated as
follows:
1.6.2.1 Customized Setup
Again as in case of linear welding, customized setups for pipe welding can be availed
from the major players in the field. These setups provide fast and precision solution
for pipe welding which can be beneficial to relevant fabricators.
1.6.2.2 Attaching a Rotary Mandrel Unit
An attachment consisting of a rotary turntable and mandrel can convert an existing
setup of linear welding to a circular welder. Sometimes, the attachment consists of
an expanding mandrel which can hold pipes with diameters varying within a certain
range. Generally, in these types of setups, the FSW tool remains fixed and the rotating
mandrel turns the pipes, thus producing the weld. It is obvious that the rotation of
the mandrel is precisely controlled. Figure 1.10 shows a typical FSW linear machine
fitted with a rotary mandrel for pipe welding.
1.6.2.3 Portable Setups—Larger Scale Welding
For carrying out welding of larger and longer pipes, portable welding machines are
also available. These setups have the advantage of being installed in the field. In these
setups, normally, the arrangement is such that the tool moves along the weld seam
producing the weld as it is difficult to rotate the huge and heavy mandrel supporting
the pipes.
1.6.2.4 Issue of the Presence of Ejection Hole
As already discussed (to be discussed previously), that FSW tool leaves an ejection
hole on the workpiece at the end of the weld. This may not be problem in case of jobs
requiring linear welding as some allowance for this can be incorporated in the job
and which can be later cut off. However, in case of circular welding which warrants a
sort of continuity, the presence of an ejection hole will make the joint vulnerable and