Orbital welding is a specialized area of welding whereby the arc is rotated mechanically through 360° (180 degrees in double up welding) around a static workpiece, an object such as a pipe, in a continuous process. This method and technology was developed to address the issue of operator error in manual gas tungsten arc welding (GTAW) applications requiring precision tube and pipe welding. To ensure high-quality repeatable welds a more stringent weld criteria was set by the ASME.

In orbital welding, an automated computer-controlled process runs with little intervention from the operator.

Rodrick Rohrberg of North American Aviation invented the orbital welding process to address fuel and hydraulic fluids leaking in and around the plumbing of the X-15 Rocket Research plane.

The main components of the typical orbital welding system are the power supply with integrated computer control, the welding head, and either a wire feed mechanism or a presharpened tungsten electrode. Welding of certain sizes and material types will also require a water/coolant system. There are a large number of factors that influence the welding result. These aspects include the arc length, magnitude, and pulse frequency of the welding current, welding speed, inert shielding gas, parent material, filler material, weld preparation, and thermal conductivity. Ultimately, a high-quality weld is achieved through detailed knowledge of how to precisely adjust all these parameters for each individual welding task.

It is very difficult to achieve the highest standards of quality and safety using manual welding. This is due to certain welding positions, overhead and down-hand welds for example, often leading to faulty welds due to restricted access the user has in these welding positions. In order to have complete control over the weld pool, a perfect balance must be maintained between gravitational force and surface tension at every position of the torch. By using mechanised variants of the technique, certain parts of the welding process are handled by mechanical components. Note that a welding operator is always monitoring and controlling the process. In an ideal situation, all welding parameters would be fully programmed before welding is started. In practice, however, the presence of variable constraints means that it is often necessary for the welder to make corrective interventions and create custom programs for the application.

Orbital tube welding can use open weld heads and enclosed weld heads. Each style of weld head uses the fusion process described in ASME Section IX. No filler metal is added.

A successful orbital weld is 100% automatic and repeatable as long as the operator monitors variables and performs periodic inspections of the weld seam for complete penetration of the weld. Noticing that a variable has changed during the welding process is a necessary skill for orbital welding technicians and operators that can be easily missed. Training and experience are required for an operator to be successful at consistently producing acceptable, repeatable, high-precision welds that meet today's standards.

Several critical variables can affect the success of an orbital weld. These include using the proper weld program in the orbital welding power supply or controller to match the settings to the pipe size, wall thickness, and tube material. Other key factors include the pipe preparation and face, the correct positioning of the weld head on the tube, and the amount of oxygen present during the welding process.