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Emergency Pipe Bursting Project In Alaska Uses Chain-Drive System
Remote Pipe Bursting
“The location of the broken head was determined by measuring the distance from the exit hole to the new pipe,” Currey explained. “We then dug down approximately four feet and reattached the puller head. We determined that the problem was caused by drag from the insulation foam which required a longer tail section where the pipe bolts to the bursting head.”
The pull was completed, and the problem did not occur during the remaining two segments. The three segments were completed over a period of three consecutive days. The installation was made with Currey and two UCMC team members, four YKHC employees and four employees of the city of Pilot Station. The project served as training for the personnel who would be operating the equipment on future jobs.
By the second pull, Currey said the YKHC and Pilot Station personnel were capable of setting up and operating the equipment.
With most pipe bursting installations, pieces of the old pipe are displaced into surrounding soils as old pipe is broken and the new pipe is pulled into place. Currey said there was space in the foam-filled outer pipe to accommodate fragments of the old PVC, but they came into the pits the last approximately 20 feet of the bursts because there was less resistance. He added that if the old water pipe and its replacement had been of a larger diameter, that could have been an issue.
“With chain drive bursting, work proceeds continuously,” Currey said. “There are no interruptions to make-up and break-out rod connections and no need to handle rods one by one. Continuous chain can be installed between machine and insertion pits at up to 600-feet per hour, more than twice as fast as when using rods. On pull back, when pipe bursting, chain drive operates faster than rod systems, to more than 300 feet per hour, also much faster than compressor powered systems.
“Chain drive combines chain strength with the power to handle the biggest jobs with ease, and the smallest with economy through simplicity of equipment and operation,” concluded Currey. “And with chain drive systems, bursts can be made through curved sections of pipe.”