When high quality results are required, orbital welding is the first choice for connecting pipes.

The welding torch - in most cases, TIG welding (Tungsten Inert Gas) is used - travels around the pipes to be connected, guided by a mechanical system.

The name orbital welding comes of the circular motion of welding tool around the workpiece. In general, orbital welding technology includes coverage two main application areas.

In the first group, all kinds of pipe connections are included. butt welding and welding flanges, bends, T-fittings and valves, i.e., the complete requirements for pipes and tubes.

Reasons to select Orbital Welding

The decision for the use of mechanised or automatic orbital TIG welding can be taken for different reasons. economic, technical, organisational, and others may be more or less important or even become the decisive factor. The orbital welding process offers a large range of benefits which qualifies it for industrial applications. The major advantages are….

Increased productivity compared to manual welding

• Compared to manual TIG welding, the mechanised or automatic process leads to enhanced productivity. Repetitive work in the workshop or on-site complicated assembly jobs - orbital welding equipment guarantees that approved weld sequences are reliably repeated, hence time-consuming repair work will be reduced to a minimum.

Consistent excellent weld quality

• Generally, the weld quality obtained by mechanised equipment is superior to thatof manual welding. Once an adequate weld program has been developed, the weld cycle can be repeated as often as necessary, without deviations and virtually without weld defects.

Required skill levels of the operators

• Certified welders are difficult to find and well remunerated. However, after appropriate training, skilled mechanics are able to operate orbital welding equipment perfectly and obtain excellent results. By using this equipment expenditure on personnel can be reduced.
  

Environment

• Orbital welding can be executed even under harsh environmental conditions. Restricted space or access, lack of visibility, presence of radiation; once the weld head is positioned properly, the weld can be carried out without difficulty from a safe distance; often supported by a video transmission.

Traceability - Quality Control

• Modern orbital welding equipment is designed for real-time monitoring of the aaffecting weld parameters; a complete weld protocol can be generated and stored or printed out. Sophisticated data acquisition systems operate in the background, if they are connected directly to a superior quality management system; automatic data transfer takes place without any interruptions to the weld procedure.

Industries which apply the orbital TIG Welding Process

• Food and beverage industries
• Pharmaceutical and Biotechnology industries
• Manufacture of Semi-Conductor devices
• Chemical industries

Gases

Welding Gases

Argon is commonly used as shielding gas in the TIG process. It provides good arc striking characteristics and excellent arc stability even at low amperages, the energy of the arc is confined to a narrow area. Argon is also compatible with all types of base materials.

Shielding gas for standard TIG welding purposes should have a purity of 4.5, i.e., a purity level of 99.995%.

Backing Gas

During orbital welding, the inner surface of the tubes must be protected against oxidation. Therefore, the interior of the tube system is purged by backing gas. The purity of the backing gas depends on the required weld quality. Before the weld can be started, a sufficient purge time must elapse, allowing the backing gas to remove the oxygen out of the system.

The remaining oxygen content of the backing gas can be analysed at the outlet; if it has decreased to an acceptable value, the welding operation can begin. Usually in the case of UHP applications (Ultra High Purity) the oxygen level must fall below 10 PPM (Parts per Million), i.e., less than 0.001%.

A light heat tint, due to remaining oxygen in the backing gas, can be removed by passivation.