Weld overlay cladding

Cladding of tubes and pipes

GTAW / TIGer for CRA products

To combine the strength of low-alloyed Carbon steel with the corrosion resistance of CRAs, the insides of C-Mn steel pipes are covered with a layer of a suitable corrosion resistant alloy. Excellent bonding between the parent metal of the outer pipe and the deposited layer inside can be achieved if overlay cladding is applied. CRA clad steel pipes are characterised by the firm metallurgical bond between the host pipe and the inner CRA layer, thus meeting the highest quality standards.

 

Turnkey solutions for cladding of tubes and pipes

Turnkey solutions for cladding of tubes and pipes See our products

Horizontal weld overlay / cladding

Internal CRA cladding can successfully be carried out by overlay welding. The horizontally positioned pipes are rotated around their longitudinal axis while the torches with the attached wire feeding devices are mounted at the end of a welding lance and guided along the inner wall. A bi-cathode GTAW cladding process named TIGer, exclusively developed by Polysoude, executes a smooth surface of the corrosion-resistant layer, which together with low dilution rates between deposit and substrate, produces reliable results and significantly improves productivity.

  • Full Length Cladding Rig TWIN torch technology for 6 to 12m full length cladded line pipes + Contact us
    High deposit TWIN TIGer double torch solutions are available for the internal cladding of pipes with an inner diameter of minimum 5” and standard lengths of 6 to 12m
  • Pipe End Cladding Rig Single torch solutions for short and medium full length pipes or pipe ends + Contact us
    Two synchronized PC 600-3 HW power sources control the longitudinal movement of the lance, the pipe rotation and supply the TIGer torch

Cladding torches and lances for tubes and pipes

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Comprehensively designed systems

The performance of a weld overlay / cladding installation is defined by the duty cycle and reliability of its cladding torch or lance. Polysoude’s core business is the optimization of the TIG and TIGer technology, through the development of specific welding and cladding torches. When new torches are designed, the validation of performance levels in relation to essential functions, such as duty cycle, gas shielding, video monitoring etc. is vital.
During the design process, multiple variants can be created, in order to overcome constraints encountered whilst fulfilling individual customer requirements. Polysoude has taken advantage of acquired experience in design, has overcome issues relating to costing and timing, and is able to guarantee reliability, through the development of its range of industrialized standard torches.
The torch and lance design includes the camera solution, allowing continuous surveillance of the process, thereby ensuring easy operation and zero defects.

  • GTAW HW single torch Conventional GTAW HW torch + Contact us
    For small bore and short to medium lengths
  • GTAW HW TWIN torch Conventional GTAW HW TWIN torch lance + Contact us
    For full length cladded line pipes
  • TIGer single torch High productivity TIGer HW torch + Contact us
    For short and medium lengths
  • TIGer TWIN torch High productivity TIGer HW TWIN torch lance + Contact us
    For full length cladded line pipes

Application examples for weld overlay cladding of tubes and pipes

The GTAW weld overlay / cladding process is becoming ever more popular for the manufacturing of CRA clad steel pipes. It is known for providing a smooth and regular surface with only small variations in thickness. The layer has “zero defects”: no pores, no lack of fusion and particularly low dilution rates.

  • Conventional GTAW/ TIG welding (Tungsten Inert Gas) is characterised by the creation of an electric arc between a refractory metal (alloyed tungsten) electrode and the workpiece in an atmosphere filled with inert gas. The electrode withstands the high temperature of the arc and directs it towards the fusion zone. The impact of the electrons causes the fusion of the parent metal, forming the weld pool, which is shielded by the inert gas flow. In the case of Cold-Wire GTAW cladding the energy required to melt the added wire comes from the electric arc, so the melting rates that can be achieved are quite limited. In the case of the Hot Wire GTAW process, the wire is preheated due to the Joule effect by a separate current provided by an additional power source. Hot Wire GTAW cladding allows increased melting rates and advanced productivity without compromising the reliability of the process or the quality of the deposited layers.
  • The process of GTAW welding , particularly GTAW Hot Wire cladding applications, has been made yet more efficient as a result of a recent development, known as TIGer technology. It is based on a new torch design. Whilst a common GTAW torch has one single tungsten electrode, the distinct TIGer torch is equipped with two electrodes. Each electrode is supplied with current by its own power source. The position of the electrodes (with the tips next to each other) generates a single arc.
  • Whether the application consists of  the cladding of pipe ends only or full length line pipes, a wide choice of approved cladding tools and peripheral devices are available. The POLYSOUDE NC-weld controller synchronizes all movements of the cladding lance and the pipe rotation. Of course, the complete turnkey solution includes the optimization of the process through the development of specific welding and cladding torches and lances.