Orbital welding uses a specialised machine that clamps the tube or pipe to be welded while the welding arc rotates around the workpiece (in an ‘orbit’). Because the welding parameters are set by a microprocessor, the settings can be stored and reused, making this a highly repeatable process.
Orbital welds can be completed with either a consumable or a non-consumable electrode, with the former using power from a wire feeder to provide metal for the arc, while the latter uses the inherent orbital welding system’s encased electrodes and tungsten inert gas. Each of these methods has its own uses and benefits.
An industry has developed since the 1980s to produce fittings, gauges, regulators, valves and other items for high purity orbital welding applications. Tube welding for high purity applications require the use of a fully enclosed weld head.
For full repeatability it is also important to assess the weld head, making sure the internal parts haven’t become charred with carbon deposits that can short-circuit the flow of current. The weld head requires cleaning and maintenance to prevent parts from wearing out over time.
While this is a highly automated process, engineers are still required to operate the machine effectively. Despite the welding parameters having been input into the welding machine, variable constraints mean that a welder may need to take corrective action. This includes periodically inspecting samples or coupons for variance in weld penetration. These coupons are typically prepared at the start of a welding shift as well as at any time when adjustments or changes are made. These coupons must continue to show full penetration and consistent bead width.
The quality of orbital welds are dependent on the quality of the materials being used, with 316L stainless steel tubing being frequently used along with a source of argon for shielding and backing gas that has a minimum purity of 99.9995% for industrial applications.
The quality of the weld is related to factors including arc length, the welding current’s magnitude and pulse frequency, the welding speed, the type of parent and filler wire materials, the shielding gas, thermal conductivity and the weld preparation. Understanding and adjusting these various parameters will improve the weld quality significantly.
It can be difficult to achieve high levels of safety and quality when using manual welding in certain positions, such as down-hand and overhead. The restricted access afforded to the user can lead to faulty welds as the welder struggles to maintain control over the weld pool with a balance between surface tension and gravitational force in different torch positions. Orbital welding can solve this issue by automating the process, although a welder will still be required to monitor and adjust the process.
It is more common to use orbital welding on tubing than on pipes, since tubing production creates consistent outside diameters that are better for a proper fit up in the weld head.
Orbital welding has become a standard joining method for high integrity liquid and gas systems for the semiconductor and pharmaceutical industries, requiring high purity and leak-proof integrity.
Orbital welding should be used when manual welding would be difficult or dangerous and also when large quantities of welds are required because it is fully automated and highly repeatable.
Orbital welding offers a range of advantages over other welding techniques, including:
- Increased Productivity: Being mechanised, orbital welding equipment offers increased productivity compared to manual TIG welding since weld sequences can be easily and reliably repeated.
- Consistent Weld Quality: Once the weld parameters have been set and input, the weld cycle can be repeated with a high level of precision and consistency. Because most orbital welding equipment allows for real-time monitoring, a complete weld protocol can be created and stored for later use.
- Operator Skill Levels: Once trained, skilled mechanics are able to operate orbital welding equipment. The skill levels are lower than those required for manual welding, meaning personnel costs should also be lower.
- Environmental Conditions: Orbital welding can be performed under harsh environmental conditions as well as where there is restricted access or poor visibility. Once the weld head is in position, the work can be completed from a safe distance using video transmission to monitor the weld.
- Improved Safety: Orbital welding can offer improved safety by removing welders from the workspace, leaving them to monitor the process from a safe distance.
Despite the advantages, there are also a few limitations associated with orbital welding. The first is that not all objects can be orbital welded and, secondly, different welding heads are required for welding different objects.
In addition, orbital welding equipment can cost 5-10 times the initial capital cost of conventional welding.
The main parts of an orbital welding system are the power supply (including an integrated computer control), the welding head and, as required, a wire feed system. In addition, certain sized parts or materials will also require the use of a water/coolant system. Here we will look at each in turn:
- Programmable Power Supply: The programmable power supply allows you to set a range of different parameters, including the current intensity, pulse rate, flow of shielding gas, the welding head travel speed, and wire feed options. Ideally, the power supply should be light enough for one person to carry, be capable of controlling at least four axes, and should be compact
- Orbital Welding Heads: You may require different sized heads for different applications, but in all cases, your weld head should hold the electrode in place, manage the flow of the welding current, maintain an optimal temperature, and apply pressure on the workpieces being welded
- Wire Feeder: The wire feeder, when required, can be welded into the head of the device or part of a separate system
- Water/Air Coolant System: Using either air or water, the coolant system prevents the welding equipment from overheating, while also protecting the welding operator from the process' heat input
Orbital welding can be performed on a range of metals including high-strength, high-temperature and corrosion-resistant steels, unalloyed and low-alloyed carbon steels, nickel alloys, copper, titanium, aluminium and its associated alloys.
Because orbital welding is performed in an inert atmosphere, the results are very clean with low particle counts and no unwanted spatter.
Because it is able to create high purity welds, orbital welding has been used for producing clean-room parts for the semiconductor industry as well as pipework for a diverse range of industries. Orbital welding is found in the automotive, aerospace, biotechnology, chemical engineering, food processing, pharmaceutical, power and shipbuilding industries, among others.
As noted above, orbital welding is used in a range of industries and situations. This is because the process offers high efficiencies for otherwise complex welds as well as creating joins that are smooth and reliable.
Some example applications include:
- Food, Dairy and Beverage Components: Because these components need to meet sanitation and safety standards, orbital welding is often used to achieve welds with a good amount of smoothness and penetration for these applications
- Semiconductors: Orbital welds are used for semiconductors to deliver efficient batch welds with smooth surfaces and prevent the build-up of contaminants
- Aerospace Parts: Orbital welding has been used by aerospace for decades to create welds that can withstand the pressures associated with flying at altitude, while remaining smooth and flawless
Is Orbital Welding Hard?
Because it is automated, orbital welding is not particularly difficult to perform, although expertise and experience is still required to set the welding parameters and make any necessary adjustments during the process.
What Process is Orbital Welding?
Orbital welding is a specialised arc welding process whereby tubes or pipes are secured as the electrode rotates (or orbits) around the object to form the weld.
Orbital welding can deliver highly repeatable, reliable welds even with unusual materials, parts with a large wall thickness, small diameters or difficult/dangerous environments. These factors have all made orbital welding a widely used process for a range of industries and applications.
While the cost of the required equipment is relatively expensive compared to conventional equipment (at 5-10 times as much), orbital welding can offer productivity 2-3 times higher than conventional TIG welding.