Command Performance

Sliplining eliminates water loss and restores pressure and flow in heating system for a military prep school and junior college in New Mexico.
Command Performance
Fusing the 13-foot-long sticks of Climatherm SDR 11 composite pipe from Aquatherm left a weld bead. Workers removed the interior bead using a long pole with a spring-loaded blade that shaved off and extracted the bead. The light blue ring on the end of the pipe is the thermal liner.

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The heating system at the New Mexico Military Institute in Roswell was losing significant water, but maintenance providers had no idea where it was going on the 300-acre campus. Rust also clogged the system's water filters occasionally.

The institute hired CuraFlo Services in Mesa, Ariz., to clean and line the 1/2- to 3-inch pipes inside the buildings. CuraFlo subcontracted Triton Lining Technologies in Indianapolis, Ind., to clean and coat the exterior 6-inch ID steel supply and return pipes with a corrosion-preventive spray epoxy. When the Triton crew excavated at predetermined locations, they discovered the pipes were too corroded to rehabilitate as planned.

Open-cutting would disrupt the campus, take too long, and cost more than the allocated budget. "Our challenge was to find a solution and complete the project within the original budget," says company founder Gary Sorohan. "The obvious answer was sliplining, but we couldn't locate a North American product that would withstand temperatures of 180 degrees Fahrenheit and operating pressures of 40 to 45 psi."

It took almost a year before Sorohan found Climatherm SDR 11 composite pipe from Aquatherm (supplied by Ferguson, Indianapolis, Ind.) Made of Fusiolen PP-R, a polypropylene material, the pipe was rated at 180 degrees with a working pressure of 50 psi. After half a day's training on how to butt- and socket-fuse the product, the team rehabilitated the heating system in two phases separated by winter.

Cautious cleaning

The original pipes, wrapped in Styrofoam and cellophane, lay side-by-side in trenches 3 to 6 feet deep. The insulation and dry ground absorbed thousands of gallons of water escaping through the perforated lines.

Due to the close proximity of numerous other utilities, pipe bursting was not an option. "Vice president of facilities David West also was concerned about the number of long open trenches required by other processes," says Sorohan, who proposed inserting a 5-inch OD pipe with 4-inch ID. An engineer at the institute determined that the hydraulic efficiency of the smaller pipe would supply enough water to run the system.

As-built plans correctly identified the location of tees and 90-degree bends in all but two instances. The team excavated 5- by 7-foot-long access pits at these points for the Triton winches that pulled the cleaning tools and replacement pipe. They also excavated slip trenches at insert points to pull in the pipe without bending it.

Pairs of clamped Christmas tree drag scrapers, custom made in Great Britain and dragged through the host piping, removed incrustation and tuberculation. To prevent the aggressive cleaners from taking out the whole pipe, workers bent the blades a little so they didn't press as hard against the walls. Double sets of squeegee plugs were dragged behind the scrapers to remove tailings.

Cleaning was necessary to ensure a clear path with no surprises, and for other reasons. "If the slightly larger pulling cap hit a hard incrustation, it could lock up and we'd have no way of reversing," says Sorohan. "If debris drags in front of the cap, it will cause a blockage and stop the pull. We also don't want sharp nodules scouring the new pipe."

Fusion fixtures

Every day at noon, up to 870 cadets – with military band playing – marched in formation to the mess hall. "We had to be very mindful that we didn't block off routes or create hazards with our equipment, hoses and cables," says Sorohan.

Ernie Beaty and Brad Hoop butt-fused 13-foot-long sticks using a manual McElroy 2LC welding machine to precisely align the pipes. The process left an external and internal weld bead. "If we didn't remove the internal beads, they would cause friction or reduce capacity," says Sorohan. After each weld, Hoop inserted a long pole that released a spring-loaded blade when turned counterclockwise. Rotating the tool 360 degrees clockwise shaved off the bead and locked it in the blade for extraction.

As the team excavated where pipes turned to enter buildings, they discovered 3-inch-wide balancing valves between the supply and return tees. "That surprised us because now we had to install new valves and the closest match was 10 inches wide," says Sorohan.

The additional width made it impossible to run the tees parallel into the building. "We had to offset one, then bring it back into alignment with multiple bends," says Sorohan. "It added a lot of fittings because numerous other pipes were in the way. Assembling the offsets became the most challenging part of the project."

Where possible, the crew socket-fused what looked like a hamster maze of fittings aboveground, but too often the connections were assembled around other pipes in a narrow space or underground hole. "We worked bent over, on our knees, and occasionally upside down," says Sorohan. "The manual labor took a heavy toll on us." Everything was done by hand because automatic equipment was too large to fit in the work areas.

Under pressure

Before inserting a length of pipe, the team pressure-tested it to 150 percent of operating pressure for two hours. They then butt-fused a cap with a metal rod and eye to the pipe, attached a steel cable, and pulled in the pipe with a Triton winch. "We did 32 pulls representing 16 supply and return lines," says Sorohan. The shortest pull was 30 feet, the longest was 500 feet, and the average was 250 feet.

Once installed, they pressure-tested the line for 30 minutes at 150 percent, deflated it, and pumped to 150 percent again for two hours. The final test involved pressurizing the line to 150 percent, holding it for two minutes, deflating the pressure to 15 percent of maximum, holding it for two more minutes, then repeating the process three more times with five minutes for the final interval.

"Rapid cycling and high- and low-pressure tests ensure the fused connections are properly installed," says Sorohan. "Out of 6,000 feet, we had one leak on a coupling fused in the hole. For having never worked with Climatherm pipe before, I think that speaks highly of how user-friendly it is."

To prevent heat loss, the crew replaced insulation that had been removed with batting, or they built little frames around the pipes and filled the spaces with spray foam. They also restored sidewalks, block pavement and grass.



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