A New York company and two utilities have a cost-effective solution to the nation’s aging underground infrastructure: a robot that crawls through cast-iron natural-gas pipelines and replaces their deteriorating joints, effectively renewing the pipes for up to 50 years.
The cast-iron sealing robot, or CISBOT, can crawl as far as 1,500 ft through a single 5-ft x 5-ft hole, eliminating the need to tear up streets every 12 ft to access the pipe’s joints. The operator-controlled CISBOT fills in the joints with an anaerobic sealant while the natural gas is still flowing through the pipes. The sealant, which has been lab-tested to show a life span of 50 years if applied by the robot, replaces jute, often sealed with lead, that had been used to fill the joints in the cast-iron pipes—many of which were installed at the turn of the 20th century.
The joints are often the point of failure for the cast-iron pipes. Greg Penza, president of ULC Robotics, the Hauppauge, N.Y., company that developed the robot for commercialization, says with the joint repair, “We’re making the mains like new.” Con Edison and National Grid paid to help develop the 36-in. CISBOT, which they are using in Manhattan, Brooklyn, Staten Island, Rhode Island, Boston, Glasgow and London. Other utilities are using the robot in the U.S. and the U.K. The robot can work in pipes from 16 to 36 in. in diameter; it is being modified to work in pipes of up to 42 in.
“It reduces the difficulty on customers while maximizing safety,” says Con Edison project specialist Steve Sweeney.
The CISBOT also has the potential to save millions of dollars. The cost of robotic joint replacement is about one-tenth the cost of manual pipe replacement and one-fourth of sealing the joints manually, says Penza.
There are eight units in operation. At a total cost of about $1 million each, the individual units include a robotic system and a truck. Two more are being built.
Con Ed and National Grid last year received approval from state regulators to charge customers for the CISBOT work, leading to a ramp up of work in the last quarter of 2017. Sweeney says Con Ed sealed about 600 ft of pipe in 2017 and already has sealed 1,000 ft this year.
The 85-lb robot is launched through a tube attached to a gas main by a fitting with a 150-lb flange. Once attached, the robot drills a hole into the pipe. Then, the 12-in.-dia, 36-in.-long CISBOT rolls through the pipe, followed by a tether that includes power, communications, control cabling, pneumatic tubing and lines to deliver the anaerobic sealant. When it reaches a joint, the robot’s three wheels perpendicularly rotate to guide the robot around the pipe. The CISBOT is constantly monitored by a pilot and co-pilot who view the robot’s six cameras. The robot can seal about five joints a day, Penza says. In the process, the ULC team creates a GPS map of the joints, bends, branches and any other feature.
In addition to the CISBOT, robots now are being used to assess the condition and leaks in natural-gas transmission pipelines, says Andrew Lu, managing director of technical services for the American Gas Association.
Compared to traditional joint restoration, the robot’s impact is readily apparent to anyone who travels by the quiet CISBOT site, Sweeney notes. “It is impressive how different it is from normal street work,” he says.