Plugged pipes are a pain. If they can’t be cleared easily, a city can spend six figures digging them up and replacing them. The advent of low-speed, high-impact rotary cutting technology is changing that.
Durable, workhorse cutters can chew through concrete and other dense material, clearing a clogged pipe within minutes or hours and at a much lower cost. One of these tools, the Paikert cutter, manufactured and marketed by NozzTeq Inc. of Dunedin, Fla., is driven by water pressure and is available in a variety of sizes to fit most pipe diameters.
It is designed to work with sewer jetting units and requires no electrical connections or lubricants. Its small but powerful Hydro-Torque impact drill motor pounds into the plug at 1,500 impacts per minute, and its carbide cutting teeth spin at 200 rpm. The cutter can pulverize and flush out concrete, dense root growth, chemical sediments, mineral deposits, protruding taps and other blockages.
NozzTeq demonstrated the cutter in late August on the grounds of its distributor, Infrastructure Technologies Inc. (Infratech), in Rogers, Minn. On the scene were Scott Paquet, president and CEO of NozzTeq; Todd Sykora, project manager with Infratech; operators Jon Fashant, Mike Bohlman and Matt Kerzman, also with Infratech; and a few other observers. The test took place in a parking area behind the Infratech building.
Walk-around
To demonstrate the cutter, the NozzTeq and Infratech crew used a 10-foot length of clear 8-inch PVC pipe, and poured enough 4,000-psi Quick-Crete concrete into it to harden into a 4-foot-long plug that completely blocked the line. They set the plugged pipe on the ground and backed the plugged end against a 4-foot square of 3/4-inch plywood. Then they notched the plywood to allow an Aries pan-and-tilt camera to be inserted into the back end of the pipe to record the action.
Paquet brought out two Paikert cutters and placed them on a metal cart near the pipe. One, a model SB 150, can cut through plugs in 27- to 36-inch lines. Its companion, a model SB 110, which was used for the demonstration, is designed for pipes from 6 to 24 inches.
The cutter is a strange-looking device made of many different metals and a bit reminiscent of a propeller-driven airplane engine. The SB 110 is about 27 inches long and consists of a cylindrical motor with a cutting wheel at the business end. A dozen carbide cutting teeth are mounted on the face of the wheel. “The operator can install saw-tooth blades instead for use on roots,” says Paquet.
An adjustable sled made up of four horizontal runners called “distance plates” framed the motor and allowed the machine to fit and slide perfectly inside the pipe. The same machine can be used for different-sized pipes simply by changing the cutting head and adjusting the distance plates to different interior diameters.
Water jets, installed in the housing, provide the propulsion needed to get to the problem area. A counterweight absorbs the recoil from the impact motor action. Spent water is discharged out the front of the device to cool and lubricate the cutting head, and out the sides and rear of the device to flush out debris.
Infratech positioned two of its vehicles near the test pipe: a panel truck containing the video equipment and monitoring station, and a GapVax MC 1510 combination truck from GapVax Inc. of Johnstown, Pa. The GapVax truck carried about 1,500 gallons of water. A pressurized water hose ran from the truck to the test area.
Operation
After explaining the test procedure and reviewing the cutting equipment, Paquet connected the high-pressure water hose to a nozzle on the rear of the SB 110 cutter and tightened it by hand. He inserted the cutter into the pipe and, using the connected hose, pushed the unit down the line until it met up with the blockage. Personnel donned safety vests to simulate real conditions as closely as possible.
The operation started like a blast-off. From the truck’s control panel, Sykora turned the water flow up to about 80 gpm and 2,000 psi. Immediately, the cutter started chewing into the plug, and spent water and pulverized concrete shot out of the end of the pipe, quickly flooding the adjacent area. (In a real-life situation, the spent water would go into the sewer to be vacuumed out by the vacuum truck.)
Through the wall of the clear PVC pipe, observers could see the cutter as it broke the concrete into chunks and then pulverized those and flushed the debris out of the pipe with the jet stream of water. The machine gave the impression of a ravenous animal as it tore into the block; the concrete had no chance.
Within ten minutes, the block was cleared, Sykora shut off the water, and Paquet pulled the cutter from the pipe. Fashant withdrew the camera from the other end and the group went into the panel truck to view a replay of the videotaped action.
The onscreen image showed the cutter breaking through the concrete, eating its way through the block toward the camera until the concrete was gone. “We try to video every job,” said Paquet. “The camera also allows us to view the condition of the pipe and the extent of the blockage before we start cutting.”
Observer comments
The thrust and cutting action of the machine is very powerful. Does it ever damage the pipe it is cleaning? Or are there pipes or pipe conditions where the cutter cannot or should not be used? What about burrs inside pipe joints? Turns and corners are another question. The machine did not appear to be able to negotiate turns, only straight-line pipes or pipe sections.
The Infratech crew brought up a second water truck as a standby during the operation. “A continuous supply of water is necessary,” Paquet says. “We don’t want to run out of water and have to stop the cutter midway through a job.” In normal conditions, a hydrant may be used as the water source.
Another obvious question was how the cutter would be inserted into the blocked pipe in a real application. Would it be dropped into a manhole? If so, how? The SB110 weighs 60 pounds — what about the larger units?
Finally, it was clear that the cutting approach was less costly than excavation and replacement, but by how much?
Manufacturer comments
Paquet observes that the video camera is helpful in examining pipe conditions before the cut. “If the pipe wall is cracked or broken, that’s not going to be a good application,” he says. “Sometimes we find chunks out of the side walls, or the bottom of the pipe completely eroded. Those issues will prevent us from using the cutter because the machine needs to slide smoothly inside the pipe wall.”
The cutter could damage a pipe if there are bad offset joints or if incorrect pipe measurements prevent proper sizing of the cutting head and sled, he adds. Burrs and minor offsets at joints are not an issue: “The machine cuts them off and actually smoothes out the pipe, improving flow.”
The machine can negotiate turns, Paquet reports, but cannot be used in pipes that turn or bend more than about 7 to 10 degrees. Where corners are involved, the user simply runs the machine in from both directions. “The chunk right at the corner usually comes out, too,” Paquet says.
As for insertion of the cutter, it is positioned at a manhole or a pit at the pipe end. The crew, usually two men, drops the machine down to the pipe with a rope, then tips the machine so it’s parallel to the pipe. It can be pushed into the pipe and withdrawn from the pipe using the reel on the vacuum truck. The largest unit weighs 200 pounds.
The units are marketed through four distributors and out of Paquet’s office in Dunedin. While some units are sold outright to contractors, most are rented or leased. “We rent them by the day with a declining rate the longer it is rented,” Paquet says. Sometimes, his company provides a training package for an additional fee. On all projects, customers are asked to complete a comprehensive questionnaire to help determine the feasibility of the cutting application.
“We ask questions about the thickness of the material, the inside diameter measurement of the pipe, the psi of the material, the length of hose, and the flow capacity of the truck,” Paquet explains.
While the demonstration at Rogers took only a few minutes on a small pipe, NozzTeq can claim much larger projects. Infratech used a Paikert cutter to clear concrete accidentally pumped into several pipes during the construction of a new airport terminal in Minneapolis, and on pipes supplying the new Yankee Stadium in New York City.
“We had one chemical plant in New York state where we cleared 128 feet of pipe,” Paquet says. “The project took 18 hours of actual cutting time.”
