Product Spotlight - November 2019

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In the past, heavy concrete risers were typically used to build up a manhole or catch basin chimney so the cover and its frame could be raised during manhole construction or road resurfacing. But those risers were cumbersome and required heavy machinery to install.

As an alternative, Cretex Specialty Products offers the PRO-RING manhole grade adjustment system — a lightweight alternative to concrete grade rings or brick and mortar used in the construction of manholes, catch basins and other underground utility structures. Available in round, square and rectangular, these rings are manufactured from expanded polypropylene, known for its exceptional strength-to-weight ratio, durability, chemical resistance and long service life under harsh conditions. According to Lee Haessig, Cretex Specialty Products general manager, the product’s ease of installation and durability is its calling card.

“One man can install the PRO-RING system in just minutes to within a quarter inch of finished grade, and they are watertight,” he says.

“Where concrete rings break and may cause injury, the PRO-RING system eliminates the hazard, helping minimize the risk of injury,” says Bill Blashka, director of Public Works for the town of Sheboygan, Wisconsin.

At 7.5 pcf density, a single 36- by 24- by 6-inch PRO-RING weighs just 14 pounds and is easy for a single worker to handle and install. Alternatively, a typical concrete grade ring weighs 40 to 70 pounds per vertical inch, making PRO-RING almost 20 times lighter. The ability to hand-carry these adjustment rings into backyards, easements and remote locations makes the overall process safer and less disruptive. According to Haessig, the ease of transport and install has made the product a versatile solution compared to other grade leveling methods.

“PRO-RING was originally developed with the sanitary sewer market in mind; however, we have learned there are applications in storm sewer, telecommunications, electrical and other underground structures,” he says. “The PRO-RING system dramatically speeds manhole installation and repair time. Sites can be opened, repaired and closed in one day, reducing overall costs from 20% to 30%, based on conditions.”

Haessig points out that the rings help solve an issue that has plagued installers for decades: sinking and deteriorating manholes due to weak grade adjustments.

“The grade adjustment area is typically the weakest part of manholes, catch basins and other underground utility structures,” he says. “We are approaching the 10-year anniversary of the first PRO-RING installation that was done in the city of Beloit, Wisconsin, and recent inspections confirm that the rings are in excellent condition and remain watertight.” 800-345-3764;


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