As per the growth of Oil and Gas industries, fast track completion of projects is much demanded. In piping, work welding consumes most of the time in overall piping work. To reduce welding time Orbital welding is Introduced in the industries in the 1960s.
This is the technology to weld the pipe or tubes with higher weld quality. In the case of pipeline work, It is used on large scale to join straight length pipes. This also reduces any chance of leakage in the pipeline.
In this article we will get familiar with:
- What is orbital welding and how it helps for welding?
- Reason to selection orbital welding over manual welding.
- Factors affecting the quality of welding.
- Advantage, disadvantage, and application.
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What is Orbital Welding?
Orbital welding is a kind of specialized welding where the welding nozzle rotates 360° around the fitup assembly of the pipe is stationary in its position. The name “orbital welding” comes because of the circular motion of the welding torch around the pipe
This welding type can be made automated easily as the torch is mobile and the pipe remains stationary. This also can be easily adapted on-site for the spool fabrication process. In most cases travel around the pipe guided by a mechanism connected to torch and pipe to be weld.
Benefits of Orbital welding
The purpose of using orbital in most industries is because of its economic, productive, and technical support. The orbital welding machine offers lots of benefits and advantages as follows:
- Productivity: An orbital welding machine drastically improves welding time and productivity with respect to manual welding.
- Welding Quality: With a well-developed weld program welding quality of the orbital welding machine is superior to manual welding. This provides 100% penetration and reaches the limits of good quality welding requirements.
- Skill level of the welder: A high skilled certified welder is not an easy task to find. wherein the case of an orbital welding machine with appropriate training and understanding of mechanics of the orbital machine it can be operated perfectly with high quality of welding.
- Consistency: Once a welding program is established that can be used repetitively multiple times. This eliminates the normal variation and errors that occurred during manual welding.
- Environmental Condition: Harsh weather conditions, space restriction, lack of visibility, or presence of any radiation can’t affect orbital welding. Once all setup is done welding can be completed without any disturbance.
- Versatility: Orbital welding machine can be used where pipes can’t be rotated practically. This can be also be used in boiler tubing where manual welding is difficult.
- Cost Reduction: Because of the automated process, it is more efficient and cost-effective than manual welding. The automation here reduces the time of welding and also the chance of error or defects which ultimately saves money invested to do repair work.
Factors affecting the quality of Orbital welding
Orbital welding uses GTAW (gas tungsten arc welding) process as the applicable welding method. Electric arc produced in GTAW is the source of melting base metal and form the weld. In orbital welding there is some requirement to be fulfilled to protect the quality of welding are as follows:
- Material Weldability: Selection of material of pipe varies according to application and environmental condition. The mechanical, thermal stability, and corrosion resistance requirements also depend on the material chosen for the pipe. For complex welding applications, a significant amount of testing is required to set the quality of the required welding.
- Fitup of Weld Join: The quality of Welding depends on how perfect a fitup has been done. Weld joint fit-up also depends on the welding specification, welding concavity, and reinforcement requirement. For high-quality welding by orbital welding, there should not be any mismatch in edges of pipe and gap must be ideal for welding.
- Shield Gas: The purity of shielding gas is an important factor for maintaining the quality of welding. Any impurity in shielding gas can lead to distortion and defects in welding. Typically used shielding gases are as follows:
- 98% argon and 2% hydrogen
- 95% argon and 5% hydrogen
- 90% argon and 10% hydrogen
- 75% helium and 25% argon
- Tungsten Electrodes: Preparation of tungsten tip affects welding quality too. A sharpen tungsten tip starts to arc quickly while with a thick tip it is not difficult to start an arc. Some of advantages and Disadvantage according to tungsten geometry is as follows:
|Sharp tip Tungsten||Blunt Tip Tungsten|
|Arc easily starts||It is difficult to start an arc|
|Handle less Ampere of Current||Handle more Amperage Current|
|Wider arc shape||Narrow arc shape|
|Good arc stability||Potential for arc wandering|
|Less welding penetration||Better weld penetration|
|Shorted tungsten electrode life||Longer tungsten electrode life|
|Smaller tip Tungsten||Large tip Tungsten|
|Easier arc starting||Difficult to start the arc|
|Lower welding penetration||Better welding penetration|
|Unstable arc||Stable arc|
|Shorter tungsten life||Longer tungsten life|
Preparation Tungsten tip should be for optimum use and high welding quality according to the thickness of pipe and groove type.
Application of Orbital welding
Application of Orbital welding is much versatile in different industries some of the industries where orbital welding is used the most are as follows:
- Aeronautics/Aerospace Industry
- Boiler tube welding
- Nuclear piping works
- Food and beverage industries
- Pharmaceutical and Biotechnology industries
- Manufacture of Semi-Conductor devices
- Chemical industries
- Fossil and Nuclear Power plants
Advantage of Orbital welding machine
- Higher welding quality with respect to manual welding.
- A less skilled welder with enough training about orbital welding is enough for a welding job.
- Since welding takes much less time in orbital welding with respect to manual welding it increases productivity.
- Overall cost-efficient
- Can be applied even in a confined space as it can be accessed remotely.
- Good traceability of welding consumables.
Disadvantage of Orbital welding machine
- High initial investment for purchasing, setup, and training of workers.
- The shape of tungsten plays a vital role in the quality of welding.
- Purity and pressure of purging gas required
- Surface preparation and cleanliness are absolutely essential.
For productivity and high quality of welding that is done repetitively for multiple joints in a project, Orbital welding is the most suitable process for welding application. With a good program and enough trained work welding productivity is much higher with very less amount or no repair job.
In conclusion, the point needs to remember are:
- This can be semi-automatic or fully automatic based on use and application.
- In this welding tool of the machine rotates around the pipe which the pipe remains stationary.
- Orbital welding has been widely used for versatile applications to improve the quality and productivity of welding jobs.
- Because of its remotely accessing facility, this can be even use in confined spaces for a faster and better welding job.
- A complete setup of orbital welding setup costs much less than manual welding in terms of annual investment.