Introducing the Radial Bending Joint for Steel Pipe Microtunneling

Render of Permalok Radial Bending Joint under a busy city street.>



New Joint is First of its Kind to Allow for Curved Steel Trenchless Installation

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. Our 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.

Permalok® Radial Bending Joint (RBJ) testing at our facility in Adelanto, California.
Permalok® Radial Bending Joint (RBJ) testing at our facility in Adelanto, California.

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.

Contact us to learn more about the Permalok® RBJ and its project applications.


Contact Us

Trevor Gonterman
Director of Sales – Trenchless