Welding pipes in cramped, potentially dangerous areas is an expensive and time-consuming exercise. OC Robotics and TWI Ltd have been working on a potential solution in the form of an articulated robotic snake that navigates and welds pipes from the inside using high-powered industrial lasers.

Standard practice when it comes to welding or repairing pipes is to join two sections together, then weld them either by hand or using an orbital welding machine that clamps on the outside of the pipe. That might work on a simple straight pipe running in the open, but in the spaghetti junction of an oil refinery or a reactor container that often isn't practical.

LaserPipe addresses this problem by combining a robotic snake based on OC Robotics' Series II X125 arm with a laser-welding head powered through a fiberoptic cable by a remote laser generator. Equipped with remote location sensors, the robotic arm differs from other pipe-running robots in that it's a head-following design. That is, as the operator steers the head of the robot, its body undulates behind on the same path, touching the pipe as little as possible. When it withdraws, it retreats along the exact same path it used going in.

According to IC Robotics, the entire system weighs under 5 kg (11 lb), can fit into any weld-standard pipe, rotates 360 degrees, has 22 degrees of freedom, and has a sheath to protect it against splatters and abrasions, which gives it an even more snake-like appearance.

The head of the LaserPipe robot is equipped with high-definition cameras and a laser alignment system that allows the operator to map out the exact path for the welding laser to follow. The 5-kW laser can weld steel at a rate of one meter (3 ft) per minute with a tolerance to the joint line of 0.2 mm.

To ensure the weld is even and the laser doesn't scatter beyond the pipe, a collar needs to be fitted externally over the join. This reflects the laser back into the weld and supplies a constant stream of nitrogen gas to help cool the area and avoid fires. Meanwhile, air knives protect the robot's optics from sparks and splatters.

According to the creators, the LaserPipe system is not only able to work in confined spaces, but can also operate on tight schedules and minimizes plant shutdowns. Future development work could include improving the gas shielding technology and air knives, refinements of the laser alignment feature, miniaturization of the optics, and studying how to use the laser and robot for cutting and decommissioning work.

The technology is being developed through the year-long LaserPipe project that winds up at the end of 2015 and is part of Innovate UK's competition to produce feasibility studies under the banner of "Developing the civil nuclear supply chain." In addition to nuclear industries, the technology would also have applications in aerospace, construction, defence and oil & gas.

The video below shows LaserPipe demonstrating its capabilities.

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