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Abstract This paper presents a new generation of system for
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pressure vessel and shipbuilding. Typical pressure vessel and
ship building weld joint preparations are either traditional V, butt,
fillet grooves or have narrow or semi narrow gap profiles. The
fillet and U groove are prevalently used in heavy industries and
shipbuilding to melt and join the parts. Since the wall thickness
can be up to 6 in. or greater, welds must be made in many layers,
each layer containing several passes. However, the welding time
for the conventional processes such as submerged arc welding
(SAW) and flux cored arc welding (FCAW) can be many hours.
Although SAW and FCAW are normally mechanized pro-
cesses, pressure vessel and ship structures welding up to now
have usually been controlled by a full time operator. The opera-
tor has typically been responsible for positioning each individual
weld run, for setting weld process parameters, for maintaining
flux and wire levels, for removing slag and so on.3881
The aim of the system is to develop a high speed welding
system with multi-torch for increasing the production speed on
the line and to remove the need for the operator so that the
system can run automatically for the complete multi-torch multi-
layer weld. To achieve this, a laser vision sensor and a special
image processing algorithm have been made. Also, the multi-
torch welding system can be applicable for fine grained steel
because of the high welding speed and lower heat input com-
pared to a conventional welding process.
Keywords Adaptive welding · Multi sensor data fusion ·
Seam tracking · Welding process control1 Introduction
Recent developments in sensor hardware and in advanced soft-
ware have made it feasible to consider automating some of the
most difficult welding operations. This paper describes some
techniques used to automate successfully multi-pass submerged
arc welding operations typically used in pressure vessel manu-
facture, shipbuilding, production of offshore structures, and in
pipe mills.
For various reasons, including:
• The size of the weld joint
• The method of forming joint profiles
• The methods of forming parts from plates
• Thermal distortion during welding
there can be significant variation in weld joint shapes and areas,
not only from part to part, but also within the same part. For
example, if two cylindrical cans are tack welded together but
not lined up accurately before tacking, the joint shape and area
will vary in a predictable fashion around the circumference of
the part. These variations mean that the sensor system must be
capable not only of seam tracking but also of sophisticated pro-
cess control. While adaptive welding has been used with good
results in industry for some time [1], it has not previously been
applied successfully to such a complex application. Hence, one
of the main requirements for these systems is to provide com-
plex process control dealing effectively with a wide range of joint
variations.
An important consideration in multi-pass welds is that a very
large amount of value may have been added to the part before
a particular welding operation is started. For example, in pro-
ducing tubular components for offshore structures or pressure
vessels, by the time the circumferential outside weld is begun,
the plate has been cut, edges have been prepared, the plate has
been rolled, and inside and outside longitudinal and inside cir-
cumferential welds have been completed and tested. This means
that the welding operation must be extremely reliable, minimiz-
ing the possible generation of any defects. This is a second main