Northwest Pipe Company is the largest manufacturer of engineered steel pipe water systems in North America. With our strategically located Water Transmission manufacturing facilities, including two Permalok® facilities, we are positioned to meet North America's growing needs for water and wastewater infrastructure. We supply large-diameter, high pressure pipes, manufactured through a double-submerged arc weld process, in diameters ranging from 18-inches to 156-inches. Projects are engineered to customer requirements and include a wide variety of internal pipe linings, external coatings, and custom fabricated fittings. Two of the Water Transmission facilities manufacture the proprietary Permalok® interlocking pipe joining system that takes the field butt welding out of joining steel casing pipe.