Orbital welding really comes into its own in industries where thin-walled pipes are welded to a consistently high quality. These include semiconductor production, food technology, aerospace, pharmaceuticals and chemicals as well as heat exchanger construction - in other words, wherever aggressive and corrosive media or high process pressures require leak-free piping and high hygiene standards.

The demand for orbital welding systems is constantly increasing due to the high level of quality awareness and the shortage of skilled workers. Increasing documentation requirements also play their part, as this process meets international requirements thanks to intelligent welding power sources and defined processes.

Orbital welding head types for thin-walled pipes

An orbital welding system such as the one from Orbitalum consists of a power source with control unit and cooling unit, the welding head with hosepack for the supply of control signals, shielding gas, cooling medium and welding current. A distinction is made between closed and open welding head types. Closed heads and the tungsten inert gas welding process (TIG) are used for thin-walled pipes made of stainless steel or titanium, for example, with diameters of up to around 170 mm and wall thicknesses of 0.3 to approx. 3.5 mm. The welding process takes place under constant conditions in the orbital welding head, which completely surrounds the pipe. Under a permanent shielding gas atmosphere, a TIG electrode is guided around the pipe in a defined manner via the welding head rotor. The pipes to be welded are butt-welded together (without gaps or offsets) using an arc. This requires good seam preparation: pipes cut at right angles, a consistently flat chamfer and a metallically clean and burr-free surface can be achieved using orbital, pipe cutting and chamfering machines.

The dimensions of the welding heads have become increasingly compact over the course of development, meaning that welding can now also be carried out in confined installation spaces. Closed welding heads are currently available for pipe diameters from 3 to 170 mm.

Open orbital welding guns are often used for larger wall thicknesses and pipe diameters up to 270 mm. In contrast to closed systems, the open arc makes it possible to feed additional material into the weld pool in the form of cold wire. Multi-layer welds with thicker wall thicknesses are also possible in this way.

Intelligence in the welding process

Pipe cutting and chamfering machines are used to prepare seams for orbital welding. © Orbitalum

The handling of the welding process using the example of the closed welding heads is simple: The head is opened and the two pipes to be welded are inserted without a gap. The pipe joint is aligned with the electrode. After closing the head and starting the process, the liquid-cooled head is reliably flooded with argon gas. After arc ignition, the electrode moves cleanly around the workpiece. Tarnishing is prevented by the permanent shielding gas cover. Welding takes place automatically, without offset or gaps and with consistently high quality.

Intelligent welding power sources ensure operating safety during the process: by entering workpiece-dependent parameters such as material, diameter and wall thickness, the power source automatically determines the appropriate currents, pulse times, welding speeds and, in the case of open welding guns, the required wire quantity for the application.

The connected head type is automatically detected so that the operator only has to call up the corresponding welding program and start the process before welding begins.