The Weld Clad Overlay process is not used for general-purpose parts jointing, let’s get that fact straight from the get-go. Like the term implies, overlay welding is intended to add layer “cladding.” Essentially, with a workpiece mounted on a turntable, a stationary arc welding torch deposits a protecting layer, which entirely coats a lesser material base. This metallurgically bonded plating then acts as a corrosion-inhibiting barrier. Less actual welding and more protective parts shielding, the process coating is designed to protect pipes, industry fittings, flanges, and valves from material-adverse environments.

Welding Dissimilar Alloys

Let’s put material fusing techniques out of mind, just for now at least. What’s taking place here is quite different. Rather than bonding two separate but material-similar metal faces together, this welding procedure binds dissimilar metals. Just for the purposes of this example, the imagined part resolves as a large pipe. It’s maybe a metre in diameter, and it’s made of a cost-effective alloy. The lower cost steel will work well as a material base in a hundred-kilometre pipeline. Only, there’s a problem. The pipe metal will oxidize. To the rescue, a machine-operated Weld OverLay (WOL) rig starts to apply a coating of Inconel or stainless steel. Bonded to the base metal, while the pipe section rotates on the equipment turntable, the new surface skin applies as an anti-corrosion envelope.

Weld Clad Overlay Benefits

It’s not exactly difficult to pick out the advantages. A whole pipeline could be built out of Hastelloy, out of tungsten and molybdenum pipe sections, but imagine the exorbitant costs as each solid superalloy section extended a terrain-crossing pipeline. Instead of making an entire pipeline out of those superior but expensive alloys, they’re laid down as a metal-bonded substrate. That fused coating protects pipelines. Ultimately, it’s almost as if the entire line were actually made out of that protective surface cladding, as established by the weld overlay equipment. Again, the process is not restricted to pipeline applications. Valves or fittings, vessel shells or flanges, the rust-resistant plating forms as that remarkably tough surface overlay.

During the process, if a base alloy is rust prone, it’s hoisted onto a turntable and rotated until the stationary welding torch has done its job. Taken off the rig, the cladding is ready to perform like a superalloy. To all intents and purposes, it is an oxidation resilient workpiece. Only, the underlying parent metal is actually a regular alloy, so those normally expensive surface properties don’t exact superalloy costs. That’s clearly a compelling process feature, one that makes Automated Weld Clad Overlay technology an attractive industry option.