Steam Utilidor Replacement, Washington Correctional Center, Department of Corrections, Shelton, WA
This project replaced the steam and condensate distribution facilities at the Washington Corrections Center by providing new steam and condensate piping from the steam plant to all buildings served by the steam system. Site piping was routed through at-grade or below-grade utilidors, building crawl spaces, tunnels, and overhead areas, and tied into existing piping serving each building’s mechanical room.
The utilidor system selection was based on economy and the need for easy and quick installation in the difficult environment of an operating prison. This system included pre-cast utilidor sections with removable lids and cast-in-place manholes for steam traps, branch valves, expansion joints, and low point drains. The cast-in-place manholes allowed the system to be customized for the terrain, building tie-in points, and existing underground utilities that had to be avoided. Design loading was in accordance with H-20 wheel loading.
The piping systems were designed and tested in accordance with the applicable ASME B31.1 Power Piping Code. All steam and condensate piping and supports were analyzed using the AutoPIPE pipe stress analysis program.
Thermal expansion of the steam and condensate piping was compensated for through the use of expansion joints or expansion loops. Pipe insulation thicknesses conformed to the Washington State Energy Code.
The layout of the utilidor piping avoided major underground utilities and shutdowns for their relocation. Where major underground utilities such as duct banks for power and communications could not be avoided, the utilidor piping was routed over or under with short pipe sleeves terminated in manholes to provide inspection and drain points. Where buried utilities were shallow, the utilidor was installed deep enough to clear the utilities and avoid the expense of extra manholes and pipe sleeves.