About the Project
Interior pipe welding is a process in which a welder must climb into a pipe to weld the interior seam between two pipes. This complex task comes with its own dangers including confined spaces, high internal pipe temperatures, potential fires, and potential electrical shock. Welding accounts for around 25% of all occupational accidents with an injury rate that is 100 times higher than the average. In efforts to decrease the amount of danger of interior pipe welding, SUNDT Construction has approached NAU with a capstone project. The task is to design and build a semi-autonomous welding robot that will be used at the Gilbert North Water Treatment Plant's reconstruction and expansion. The project entails 1.6 miles of below-ground steel pipeline welding, with around 290 interior welds valued at $280,000 and requires reliable and efficient welding methods to meet demands for high-quality craftsmanship.
Requirements from SUNDT have been provided and include the following:
Given these requirements the team has developed metrics to ensure that these are met. The robot must be able to: successfully self-perform an interior pipe weld with minimal human interaction, traverse the interior of pipeline under its own power, be operated by the majority of site personnel with minimal training, and meet/exceed welds to the quality and speed of the welds performed on site.
To summarize the function, the robot will enter the pipe by which sensors will activate, providing a spatial analysis of the pipe to the brain. The brain will then instruct the motors on the body how to center itself to ensure that the robot is moving along the center of the pipe. The seam will be sensed telling the robot to stop and begin mapping the seam needing to be welded. Once an accurate mapping of the seam has occurred, the welding arm will rise and extend to match the internal radius of the pipe. The operator will confirm that the weld seam mapping is correct and will give the robot the “OK” to begin welding. The arm will be rotated around the circumference of the pipe welding as it goes.
Given this information, a design in progress to solve this problem will be presented. The current design utilizes several different components and has been split into the robot body and welding arm as subcomponents. The body will consist of a sturdy chassis designed to house the welder, onboard fire suppression, motors, brain, and sensors to allow the robot to navigate through the pipe. The arm will consist of a rising and extending motion to be able to reach pipe diameters from 4-6 feet.
With this solution, SUNDT hopes to eliminate the high-risk factor involved in interior pipe welding, while offering a safe, reliable, and economically efficient alternative.
