Hybrid laser-arc welding offers many advantages compared with conventional
arc or laser welding. The process does, however, require a high level of control if high-quality
welds are to be produced. This project tackles the issues of weld quality and productivity improvement
for manufacturing tubes and pipes through development of advanced sensors for the hybrid laser-arc
welding process. Hybrid process development must be performed for each material to be welded, with
the main focus in this project being on austenitic stainless steels and C-Mn steels. By developing
and integrating sensors that monitor weld quality and allow process modification, the project will
increase the quality and productivity of European tube and pipe manufacture beyond the state of the
art, enabling it to overcome foreign competition.
There is a large industry in Europe for pipe and tube
manufacture with many users of the finished product around the world. Competition in manufacture
from outside Europe is high, and increasing, particularly from Far East
countries. In current manufacture, conventional arc welding processes, such as MIG/MAG and submerged
arc welding, are mainly used to produce finished pipe and tube over a range of materials, diameters
and wall thicknesses. Some of the problems facing tube manufacturers include production of too much
scrap product due to process inconsistencies, lack of on-line quality control, inconsistent equipment
operation, inconsistent joint preparation and presentation, low productivity and reliance on the skill
of operators to change process parameters to maintain weld quality, particularly during changeovers,
i.e., when tube material, diameter and/or wall thickness is changed. The European tube and pipe
manufacturing industry needs to increase both the productivity and the quality of its products,
to become more competitive and to safeguard employment in a fast-changing market.
The time taken to weld a tube contributes significantly to the cost of the finished product;
indeed for some tube types the welding time is 50% of the total manufacturing cycle time. For this
reason, the welding task becomes a critical path in the whole production process, not only for
economic reasons, but also because this can influence delivery time. This in particular, is
becoming more and more important as users require “just-in-time” sourcing of product
and components. Furthermore, customers are now demanding better weld quality, as the need for
a “fit-for-purpose” product is better recognised and costs of failure escalate.
Mechanical failures, the third most frequent cause of spills for oil lines, are often the result
of weld imperfections that can be traced back to the welding during manufacture. In operation,
many pipes and tubes contain hazardous substances and the consequences of a weld failure is
therefore very significant, not only in economic terms, but also in terms of the environment,
and for human and other life forms.
The SME Partners in this project include end users in the pipe manufacturing sector,
manufacturers of sensor equipment, and software system integrators. Some of these already have
involvement with the tube and pipe manufacturing sector, whereas others wish to increase their
involvement with this sector. They have a common need to generate new markets with the
introduction of new and competitive products. The approaches to the concepts of monitoring and
hybrid laser-arc welding of pipes and tubes that will result from this project will therefore
be equipment-independent, maximising the scope for industrial use of the technology.