The orbital welding process gets its name from the fact that an electrode rotates around, or "orbits," the stationary product being welded. As with tungsten inert gas (TIG) welding, an electric arc is produced between a non-consumable tungsten electrode and the metal that is welded. The weld pool is composed of the base metals themselves. Orbital welding is especially valuable in applying quality welds to tubes and pipes, as well as for other difficult or complicated welds.
In the 1960s, the aerospace industry realized the need of a specialized welding procedure for fabricating aircraft hydraulic lines. The solution was a device to rotate a tungsten electrode around a tube-weld joint. Regulating the weld current with a control system automated the entire process. This resulted in a more precise, consistent, and reliable method, instead of manual welding. Orbital welding is simply an automatic, computer controlled gas-tungsten-arc-welding (GTAW) process. The welder sets the welding procedure parameters via the computer, and then visually monitors the automated process to assure it is welding to specification.
In the 1980s the development of portable power supply/control systems that operated from 110-V AC, made orbital welding practical for many industries. Today orbital-welding systems have computer programs that can store welding parameters in memory. This basically allows the skills of a certified welder to be programmed into the system, enabling the ongoing production of identical welds, and virtually eliminating welder error and defects.
The commonly used 300-series stainless steels offer a high degree of weldability using orbital equipment, except for types 303/303SE, which contain alloys for ease of machining. The 400-series stainless steels, while weldable, may require post-weld heat treatment. Welders adjust the orbital-welding setup to accommodate for potential differences among material heats.
Industrial Applications for Orbital Welding
Aerospace: The aerospace industry was first to use automated orbital welding. The high-pressure hydraulic systems of a single aircraft can contain more than 1,500 welded joints.
Boiler-tubes: Boiler-tube installation and maintenance offer perfect scenario for orbital welding. Compact orbital weld heads can be placed in between rows of boiler tubes.
Food, Dairy and Beverage Industries: This industry sector requires consistent full-penetration welds on all weld joints. For maximum piping-system efficiency, the tubing and pipe welds must be as smooth as possible. Any defect or incomplete weld joint can trap fluid inside the tubing or pipe, harboring bacteria.
Nuclear Piping: The nuclear power industries severe operating environment, and specifications for high-quality welds, has long been a user of orbital welding.
Offshore Applications: Submerged hydraulic systems, welded with orbital equipment, offer superior corrosion resistance and mechanical properties.
Pharmaceutical Industry: Pharmaceutical process lines and piping systems require high-quality welds to ensure a source of water (for example) from the tubes is uncontaminated by bacteria, rust, or other contaminants. Orbital welding assures full-penetration welds with no overheating that could affect the corrosion resistance in the welded joint.
Semiconductor Industry: The semiconductor industry requires piping systems with extremely smooth internal surface finish to prevent contaminant buildup on the tubing wall or weld joints. A build-up of particulate, moisture, or contaminant could release and ruin the batch process.
Tube/Pipe Fittings, Valves, and Regulators: Hydraulic lines, oil and natural gas storage, delivery systems, and medical gas systems all require consistent quality, and defect-free welds. Orbitally welded systems provide the means to ensure high productivity of welding and optimum weld quality.
Tip: If one can find a niche fabricating small parts for the aerospace (NASA, or the Military for example), or other industries, you can establish a profitable business as an orbital welder.
Web Site Links:
Written by Brian Chalmers