Nuclear power generators require fail proof heat exchangers and the structural integrity of heat exchangers is defined by the strength of the welded joints.

The welded joints in heat exchangers are very challenging and they require reliable welding of tube-sheet joints, typical challenges include

The base thickness of the parts to be welded are very different
The materials to be welded are heterogeneous
Zero tolerance for weld defects

A special purpose robotic welding machine was developed for high precision welding which had to weld 0.7mm thick titanium tube to a 40mm thick stainless steel tube-sheet

Project highlights:

• Developed an Orbital welding mechanism with a TIG welding head
  
• Developed a Programmable sector-based welding parameters control
  
• Design and Development of Inert gas chamber to prevent oxidation of weld joint
  
• Developed locating mandrel for easy and quick location of the welding mechanism in the tube

Result :

Heat Exchanger welding system was commissioned. The machine has finished 3 years operation and has reported zero defects so far

Core Competency Leverage:

Innovation, Design and Prototyping Skills, Mechanism, Robotics, Testing and validation