Keystone installed the world’s first tapered spiral welded tower on May 7th, 2015 in Middleton, Massachusetts, USA
Keystone’s automated tower manufacturing is able to simultaneously perform all of the rolling and welding operations needed to produce tubular steel towers. Unlike conventional spiral mills, Keystone can achieve the variable diameter and wall thickness required for towers.
Trapezoidal sheets are fed into the Keystone mill, joined on the fly, and rolled and welded into the tower shell.
Keystone has performed extensive structural testing of tapered spiral welded structures under both extreme and fatigue loads. The specimens have performed extremely well, with measured strengths meeting or exceeding Eurocode structural standards
Keystone has received tower design basis A-DA Certification from DNV-GL.
Patents have been issued covering Keystone’s core technology, with additional IP in the pipeline. Patents are issued or pending in 40+ countries, and covered by Intellectual Property insurance.