Working underground is extremely perilous. Workers face limited natural ventilation and light; difficult access and egress; and exposure to air contaminants, fire, flooding and explosion. Pipeline repair robots are emerging to address the challenge.

The risk of underground work to human employees was realized in a deadly Colorado tragedy in 2007. Five workers were killed and three injured in a fire at the Xcel Energy Cabin Creek generating station. Workers were applying an epoxy coat to pipes, called penstock, that require periodic maintenance.

Developing pipeline repair robots

The dangerous work being performed by workers in the Cabin Creek tragedy is still done mostly through manual labor. A new pipeline repair robot is starting to change that.

Remote Orbital Installations LLC (ROI) and Big Sky Engineering in Wisconsin said they have developed a faster and safer alternative to manual labor for pipeline rehabilitation. A robotic platform, which the companies call “The Crawler,” can both surface-blast and line medium-to large-diameter pipe internals.

The automated units have been used to upgrade penstocks installed by BC Hydro in British Columbia. Penstocks, like the ones involved at Cabin Creek, are large-diameter pipes at hydroelectric installations that transfer water from mountain lakes down to generating turbines at a lower elevation. With infrastructure in disrepair the world over, however, The Crawler could be used in many different applications.

Environment requires ruggedized robots

In designing the automated unit, the ROI/Big Sky developers needed to identify components that would endure the stress of a filthy, dusty environment, which led them to igus — a German manufacturer of motion plastics that runs its North American operations out of East Providence, Rhode Island.

The Crawler is designed with the following igus components:

• e-chain cable carriers are used to manage and protect the electrical cables running from the lower control cabinets to the upper cabinets. They are also used within the main boom raise, which allows the boom to extend and contract as it works within the pipe.
• An igus slewing ring then allows the boom to pivot from side to side.
• Servo motor cables that direct boom movement, and in the 500-meter umbilical cord that contains power and control cables along with fiber optic cables.
• An additional cable carrier enables the wheel width of The Crawler to be adjusted as it moves within the penstock. Diameters vary from 1.5 to 4 m, and the automated unit is adjusted through the umbilical cord that is controlled by the command center operator.

The durability of the igus products was critical to the success of The Crawler.

“We’ve done several projects and we haven’t had a single failure with the igus components,” Kronz said. “Other materials have failed, but not the igus products. The slewing ring, for instance, is comparable to a ball bearing. That would have been a real problem with all the dirt that the device experiences. The igus materials don’t require any seals to protect the bearing.”