Nowadays, orbital pipe welding refers to automated welding of industrial pipes with a rotating electrode around the pipe (or tube). In fact, it has become very popular and manual welders are welcoming these Orbital pipe welding systems. This continuous process around a static workpiece is being used to enhance productivity, safety and project quality. For large projects in demanding conditions like welding pipeline, the demand of contractor in orbital welding, TIG pipe welding and pipe fitting is increasing every day. Here are the essentials to know about pipe to pipe welding.
Pipe to pipe Orbital pipe welding: Applications and Equipment
Applications
Pipe-to-pipe welding applications with the addition of filler wire are often demanded in the field of energy production (power plants) and chemical or petrochemical industries, where a wide range of base materials are used, such as:
- Plain carbon steel like for Welding pipeline
- Low-alloyed chromium or chromium manganese containing carbon steel
- High-alloyed chromium nickel steel (austenitic or with an austenite-ferrite crystal structure)
- Nickel base alloys (e.g. Inconel®alloys or Hastelloy®-alloys)
- Titanium and its alloys.
Although tube dimensions differ a great deal, the majority is in the range of 26.9 mm and 219 mm (¾" and 8") diameter and 2.77 mm to 12.7 mm wall thickness. Specific orbital pipe welding machine is required for welding such materials with multiple axes and smart management of the welding parameters.
Welding with filler wire
It can become necessary to apply filler metal in automatic pipe welding procedures if:
- Wall thickness of tubes require a preparation of their ends
- Pipes to be welded are made of different base metals
- The weld needs to be reinforced
- Strength and/or corrosion resistance could be compromised by fusion welding.
Choice of equipment
or orbital pipe welding with additional filler wire, pipe welding machine with 4 or 6 controlled axes can be used: shielding gas flow, weld current intensity, torch rotation speed, wire feeding speed and in addition with 6 axes, AVC and oscillation.
In the case of reduced accessibility of the work area, TIG / GTAW power sources with 4 controlled axes should be preferred. If easy implementation of the welding tool is required, the orbital power sources with 6 controlled axes should be the choice that is always recommended.
Pipe to pipe Orbital pipe welding: Applications and Equipment
Preparation
Preparations for orbital pipe welding are always designed as a joint without any gap at the root face. (G=0). In orbital TIG pipe welding a J preparation of joints is preferred, together with backing gas protection.
Positioning
Before orbital welding, pipes must be positioned and tack welded, without or with low wire input. The prepared pipe ends must fit together with no gap.
Multilayer Welding
This choice of welding with filler wire is used to join pipes of greater thicknesses. Two different methods can be applied:
- stringer bead technique - This technique can be used by equipment with four controlled axes. It involves placing narrow weld seams side by side.
- AVC and oscillation - Equipment with six controlled axes can utilise AVC and torch oscillation to allow movement of the torch laterally. Passes with torch oscillation can then be superimposed and/or laid side by side.
- Electrode Geometry
In automated orbital TIG welding, as AVC requires precise electrode geometry, it must be ensured that the geometry of the tungsten electrodes used, remains unchanged. Even small variations of the shape or dimension could bring about significant changes to the arc voltage used as a base value by the AVC control.
Backing Gas
Various types of backing gas can be used for different base metals.
Boundary Parameters
The facility to set boundary parameters is key to the efficiency of orbital welding. Some boundary parameters are:
- Shielding gas: type, purity, flow rate
- Backing gas: type, purity, flow rate
- Gas lens: type and size
- Ceramic nozzle: size, diameter and length
- Electrode: type, diameter, end preparation and stick out
- Wire: grade and diameter; cast n°, entry angle, impact point
- Position of the start point of the weld
- Inter-pass temperature
- Ground cable position and connection
The combined features of weld preparation for orbital pipe welding, ensure repeatability of quality welds and increased productivity.
Who we are
Polysoude specialises in the design, development and manufacture of innovative arc welding solutions. The brand is synonymous with world-leading expertise in 3 core sectors: automatic orbital TIG welding systems, automated TIG and plasma welding solutions and TIGer™ weld overlay.
Situated in Nantes since 1961, the company manufactures a variety of power sources and orbital welding equipment, like a wide range of open and closed orbital weld heads.
Nowadays, as a smart factory-oriented company, Polysoude products are all designed to be ready for Industry 4.0.
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