northwest pipe company is a leading manufacturer of welded steel pipe and tubular products. the water transmission group is the largest manufacturer of engineered steel pipe water conveyance systems in north america. large diameter high pressure pipes are manufactured through double-submerged arc welding of both spirally wound and rolled cylinders, in diameters of 24-inch through 156-inch. steel casing pipes of up to 2-inch thickness and diameters of 30-inch through 150-inch for crossings and tunnels are manufactured with the proprietary permalok® joint. steel reliners are also manufactured for the structural rehabilitation of large diameter concrete pressure pipelines. with eight water transmission manufacturing facilities, the group is positioned to meet north america's growing needs for water and wastewater infrastructure. the water transmission group serves a wide range of markets and their solutions-based products are a perfect fit for applications including: water transmission, p