“Mechanized orbital welding – i.e. inert-gas welding remotely controlled via video monitoring – is a service we have been offering for 25 years now,” explains Michael Wedemeyer, Project Director of Bilfinger Engineering & Technologies. “This technology is used wherever extreme precision is required. We are one of only a few companies that offer this type of welding process, since it requires highly trained personnel and specialized equipment and must often be carried out in tight spaces and under severe time constraints.”
As part of a project to modernize two nuclear power plants in Sweden, Bilfinger recently came up with further refinements to the conventional process of orbital welding. This new, high-tech approach allows composites consisting of stainless and unalloyed steel to be welded mechanically without having to apply the buffer layer customarily used. Consequently, this generally time-consuming process can be dispensed with.
“Every minute counts when you are performing maintenance measures,” says Wedemeyer. “The work goes on day and night over a total of three shifts. We cannot afford to make any mistakes in the process. So we do a run-through of all the workflows ahead of time and also maintain an in-house training center at our Osterode location, where we can test and refine various welding methods.”
Orbital welding is a fully-mechanized gas-shielded welding process in which the electric arc is mechanically guided without interruption around pipes. With the procedure that was newly-developed by Bilfinger, mixed seams of stainless (austenite) and unalloyed (ferrite) steel can, for the first time, be mechanically welded without the need for the otherwise necessary secondary step (puffering).
The new process is particularly suited for situations requiring the utmost precision. This is typically the case in the nuclear power industry, for example. Pharmaceuticals is another sector where high-tech orbital welding often is called for.