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F (82 C) temperature, with pressure rating depending on their wall type (SDR). PP-RCT pipe also may include reinforcement layers for benefits such as reducing longi- tudinal thermal expansion/contraction. Frailey looked to REHAU's PEX tubing for the snow- melting loops embedded in the concrete pathway, and to Uponor for the PP-RCT supply and return piping as opposed to steel or other metals. This would be Thermal Engineering's first major project using polymer PP-RCT piping. Shipped in 19-foot lengths, a stick of 4-inch (125 mm) PP-RCT weighs 63 pounds - a fraction of its steel counterpart. The lighter weight not only made installation faster and easier but also eliminated the heavy weight bur- den on the structure itself. Plus, PP-RCT connections are heat-fused as opposed to welded. This was a big benefit for Frailey, who is always concerned about the jobsite safety of his workers. Additionally, the ability of the PP-RCT to form a mono- lithic pipeline and still be flexible enough to follow the movement of the bridge was one of the biggest advantages for Frailey. "The structure is intended to move in every direction all the time - left to right, backward and forward, up and down," he says. "I was concerned about the joint integrity of a steel piping system with all that movement, of its heavy weight, steel piping would require numerous installers, heavy lifts and a lot of welding. Frailey was concerned about the safety of welding that high off the ground under the bridge deck while cars, trucks and buses would be moving underneath. He had several other concerns as well about the func- tion of steel piping on the project. The weight of steel piping would have a significant impact on the structure. As all bridges are designed and constructed to move, rigid steel pipe would need special accommodations to with- stand that movement. In addition, the corrosive chemicals used on the freeway below the bridge could splash up and impact metals on the underside of the bridge. Versatile Plastic Piping Investigating piping alternatives, Frailey learned about and eventually recommended PP-RCT - a durable, light- weight, noncorrosive polymer pipe offering numerous benefits for the project. It would be easier for installers to handle high up on the bridge, eliminated open-flame welding, could flex with the bridge's movement, plus it could withstand the salt and magnesium chloride that Utah uses to melt snow and ice on its highways. PP-RCT is a polypropylene random copolymer with modified crystallinity and temperature resistance. PP-RCT piping products are rated for continuous operation at 180