Denso Protal Stands Up to Canadian Winters

After beginning one of North America’s largest hydro-electric tunnelling projects at Niagara Falls, the Ontario Power Generation company needed to supply vertical access to a 47.2 ft diameter tunnel being bored 459 feet below the surface. When completed the tunnel will measure over 33,000 feet in length.

The project called for five 36inch diameter fresh air shafts to be bored vertically from the surface into the tunnel. These shafts will also provide equipment access and pump access for emergency water evacuation.

Denso North America Inc – Canada, a subsidiary of Winn & Coales International Ltd, was chosen to supply Protal 7250 and Protal 7125 epoxy based liquid coatings to all the exterior surfaces of the vertical steel pipes, each shaft covering a distances of nearly 500 ft vertically, linking to the horizontal tunnel beneath, Each of the five shafts was spaced approximately 13 feet apart along a specific section of the tunnel.

Each pipe section was coated in plant with Protal 7250 and shipped to site where it was hosited by crane and lowered into the shaft. Using a collar arrangement to prevent the pipe length from slipping down the shaft, each hoisted pipe section was welded in place and lowered into the ground. The girth weld area was brush coated with Protal 7125 and the entire process was repeated until all the sections were finished. The vertical shaft work was completed in the winner months at sub-zero temperatures, hence the use of Protal 7125 which is specially formulated to cure at temperatures down to -20O.

Members Area

Institute Technical Forum