Northwest Pipe Introduces Radial Bending Joint for Steel Pipe Microtunneling — TBM: Tunnel Business Magazine

Northwest Pipe Company has developed the Permalok Radial Bending Joint (RBJ) that enables steel pipe to be installed in a curved radius in microtunneling applications.

This patent-pending technology is a groundbreaking advancement in trenchless construction. The Northwest Pipe team developed the proprietary joint design to meet the rigorous demands of microtunneling along a radius curve using steel pipe—a first in the industry, according to the company.

Permalok steel pipe is most often used as a casing pipe for utilities and excels in trenchless jacking applications including microtunneling, pipe jacking, auger boring, and pipe ramming. The press-fit machined joints reduce field time by eliminating butt-weld joints and result in a shortened install duration and reduced field costs, all with the proven benefits of using steel pipe. To solidify the joint’s validity, the Permalok RBJ has undergone Finite Element Analysis at the University of Thessaly, Department of Mechanical Engineering.

“This joint changes the way we have all thought of microtunneling construction,” states Scott Montross, President and Chief Executive Officer of Northwest Pipe Company. “We have developed a solution that enables steel pipe to curve during trenchless construction, which makes microtunneling even more feasible in constrictive or challenging environments. For years, trenchless applications have been limited by a straight installation path—but not anymore.”

Northwest Pipe Company manufactures Permalok RBJ pipe in diameters varying from 30 to 156 inches. The actual curve radius is dependent on site conditions as well as the pipe diameter and length.

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