LTTS Develops Autonomous Welding Robot for Offshore Pipeline

Offshore pipeline infrastructure is generally exposed to harsh environmental conditions, and the quality and durability of fabrication and repairs is highly dependent on the welding systems employed. Automated welding robots with autonomous capabilities are now increasingly being preferred to mechanized or semi-automatic welding operations as they offer increased efficiency, consistency, and quality of weld, while resulting in reduced cost and safer conditions for employees. The industrial products division of LTTS offers innovation and R&D in power and machine tools by creating energy-efficient and rugged devices suitable for extreme conditions; it also helps clients to design and develop digital manufacturing solutions that are smarter and more efficient. Using their in-house expertise, LTTS developed a battery operated autonomous welding robot system, which can intelligently weld depending on the varying thickness of the pipes. This solution was built for a major pipeline manufacturer to be used at an offshore facility.

Background and Challenge:

The client wanted to develop an engine-driven, portable tungsten inert gas (TIG) welding machine for certain pipeline dimensions and process specifications. Portability of welding equipment becomes critical in offshore conditions, where access to the power source can become difficult. The welding robot was needed to weld 1-inch thick pipe that had to fit:

• 8-inch outer diameter pipe for internal welding for two passes of 16 minutes duration
• 20-inch outer diameter pipe for internal welding for two passes of 42 minutes duration
   

The Solution: According to the demands of the power source and process requirements, LTTS developed a specialized pipeline welding system, with battery backup. They developed a TIG welding solution with DC source to deliver 170 amps at 100 percent duty cycle. The company also identified the correct battery chemistry and optimized it to support 16 and 42 minutes welding at full load, and designed 5.5 kW power converter prototype with the following specifications:

• Power Density of 2.8 kW per litre
• Peak Efficiency of 95 percent
• The machine was equipped with a 42-minute full power battery life.
• Switching Frequency of 100KHz for silicon carbide (SiC) power devices
• Liquid cooling to keep the temperature of the machine under control
• IP-67 compliant solution, which means it is protected against dust and water immersion
   

Quantifiable Benefits: The client now had an autonomous robotic solution that was capable of internal welding of pipes as small as 8 inches outer diameter, and ensured high weld integrity. Accurate estimation and validation of suitable battery chemistry is important to assess the capacity and discharge time. The client now had a battery that could provide constant power for 90 percent of the discharge time. Moreover, the new solution was compatible with the client’s existing systems for internal pipe welding.

Battery powered welding machine is ideal for remote locations with safe charging and discharging features, and is energy efficient.  It speeds up the entire process, and can be used in areas that are difficult and dangerous to access.

Keywords: Energy Efficiency, Machine Tools, Product Development, L&T Technology Services, ARC Advisory Group, Value Engineering, Welding Robot.