The tallest building west of the Mississippi relies on PEX pipe

Cross-linked polyethylene pipe helps the new Wilshire Grand Center building in Los Angeles — the highest skyscraper west of the Mississippi River — stand tall.

Literally.

Flexible PEX pipe from Uponor Corp. circulated through the concrete base of the new $1.35 billion, 73-story tower to cure the concrete in the 18-foot deep base of the tower.

The Wilshire Grand Center officially opened June 23. It houses 400,000 square feet of office space, restaurants and the 900-room InterContinental Hotel.

Uponor's PEX remains in the 18-foot-deep base having completed its mission in March 2014. The pipes and tubes are filled with grout.

Skokie, Ill.-based CTL Group, doing business as Construction Technology Laboratories, provided the theoretical thermodynamic expertise on how to cure such a mass concrete construction job.

For the project, "we looked at several different products" including Uponor PEX, said Bill Thomas, estimator and project manager in the piping division of Couts Heating and Cooling Inc. of Corona, Calif. Thomas retired in early 2016 but talked to Plastics News about the project in 2014.

Couts was the major design contributor on the PEX portion of the project for structural concrete supplier Conco Cos. in Fontana, Calif.

"We needed to get it through the rebar," Thomas said. "For testing, we took a 20-foot loop to run along the rebar. We found it was the most pliable to loop back, and then we connected it with nylon cable zip ties."

Uponor North America produced the pipe in three sizes at its Apple Valley, Minn., manufacturing facility and headquarters. "They fabricated to our specifications so we could place it between the rebar," Thomas said.

Couts purchased the 90,000 linear feet of PEX pipe through Uponor sales representative Keyline Sales Inc. in Downey, Calif. That included 1,500 feet of 8-inch main lines, 8,500 feet of 3-inch pipe and 80,000 feet of 0.75-inch tubing.

"We needed to have the rebar less than 10 inches" from the bottom of the site, he said.

Workers cut PEX tubing in lengths of 40-45 feet, placed them in 2,000 vertical drops at four-foot intervals and connected the loops with nylon cable zip ties en route to the header lines and eventually the pumps.

Four heavy-duty chillers circulated 800 tons of water to draw off heat and cool the concrete during the curing cycle following the pour.

During 2014, workers turned on and energized the radiator system on Feb. 15 before the start of the continuous 30-hour pour and kept the water running for 14 days. "We turned it off in early March," said Dave Bushnell, structural trade manager for prime contractor Turner Construction Co.

The North American building solutions segment accounted for 24.8 percent, or $290.4 million, of the 2016 sales of $1.17 billion for publicly traded Vantee, Finland-based Uponor.