Spacers Provide Pipe Support, Joint Restraint

The Pascal Construction Company of Golden, Colo., recently completed the Murphy Creek and Sand Creek Interceptor project in Aurora, Colo. Where it passes under a highway, the line was installed inside a casing pipe with the aid of restrained casing spacers.

The Pascal Construction Company of Golden, Colo., recently completed the Murphy Creek and Sand Creek Interceptor project in Aurora, Colo. Where it passes under a highway, the line was installed inside a casing pipe with the aid of restrained casing spacers.

The 10-mile pipeline will convey 4 mgd of reclaimed water from the Aurora Reuse Wastewater Treatment plant to the new Murphy Creek Golf Course. It will provide for irrigation and other miscellaneous uses. HDR Engineering of Denver designed the project and Project Manager was Kevin Meador.

The project incorporated use of the Uni-Flange Restrained Casing Spacer from Ford Meter Box. It is the only casing spacer to combine axial joint restraint (thrust restraint preventing pipeline separation) with casing spacer performance.

The spacer serves as two products in one and can reduce material inventories and installation costs. No special off-site fabrication is required. The Uni-Flange system uses standard, off the shelf components that can be added to the restrainers on the job-site. Parts are interchangeable and the installer can "custom build" each spacer according to job-site conditions.

Stronger and tougher than conventional casing spacers, the Uni-Flange restrained casing spacers are built for the conditions encountered when pulling or pushing a carrier pipe through a casing. The body of the restrainer is manufactured of ductile iron. Runners are made from ultra high molecular weight polymer. They offer a low coefficient of friction, helping the carrier pipe glide over the surface of the casing. The runners also provide dielectric insulation between the carrier pipe and casing and will not absorb moisture.

In the Murphy Creek and Sand Creek Interceptor project the carrier pipe was 16 inch AWWA C-905, DR-25 PVC pipe. When the pipe was installed underneath the E-470 tollway to Denver International Airport, it was placed inside 30-inch steel casing pipe. Uni-Flange restrained casing spacers were used during the installation to prevent joint separation during thrust conditions and to support the pipe inside the casing. The specially designed polymer runners were used to help install the pipe in the casing, acting as friction reducing "sleds."

The highway authority wanted the line installed in its maintenance corridor, which required placing the line at a diagonal to the highway and made it 80 feet longer than a perpendicular placement. Because the system will not be operational for more than two years, each end will be sealed, but no sand will be blown in to the annulus.

The 16-inch pipeline was successfully tested at 150 psi with the Uni-Flange restrained casing spacers acting as the only form of thrust restraint. Operating pressure will be 70 psi.

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