It’s not every day you get to climb a cell tower, and if you are afraid of heights this is not the job for you! Terracon was recently retained by Wirenet Company to perform a visual weld inspection on strengthening improvements made to a 330’ high cell tower. The tower inspections were required to verify wind load capacity, following the addition of a new antenna arrays which were recently installed.
To perform the inspections, Chris Dumford, an AWS QC-1 certified welding Inspector based in Cincinnati, was required to climb the tower to visually inspect the welds at each bolted flange. A total of nine flanges on each of the tower’s three legs needed inspection. Before the climb, Chris prepared by gearing up in the appropriate personal protective equipment (PPE) that included rubber-coated gloves, climbing harness with cable grab attached, high visibility vest, hard hat, and safety glasses. Since activities like a tower climb are never performed alone, Wil Beckwith, P.E., materials engineering manager, accompanied Chris during the tower inspection.
Only one leg of the tripod tower had pegs for climbing, so Chris was required to climb over to the other tower legs and rappel down each of the other two legs to complete the inspection. Part of Chris’ PPE was repelling gear that included a special harness and a safety rope that allowed him to rappel down each of the other two legs to perform the inspection. It took nearly 13 minutes to reach the top of tower by climbing up the pegs, and the inspection required him to climb the tower three different times. Chris inspected each of the welds for typical defects including cracks, undercut, overlap, porosity, and proper weld size. He deemed the welds acceptable per the provisions of AWS D1.1.
The Inspection of the cell tower included viewing welded stiffener plates, above and below connection flanges, for each support leg pipe section. These stiffeners were designed to add additional resistance to tower deflection at the bolted pipe flange connections. Each welded stiffener required multi-pass fillet welds with weld sizes that varied from 3/16” to 7/16” depending on location. The welding operations had taken several weeks to complete.
Climbing a cell tower is no easy feat. Terracon is fortunate to have the resources, and the no-fear-of-heights experts like Chris – who has climbed over 40 cell towers during his career. In fact, Chris has done some recreational climbing and rappelling, which comes in handy on the job. Terracon’s many years of experience allow us to perform inspections on towers up to 400’ high as well as light poles, high-line electrical towers, windmill towers and other unusual tower structures for clients who need quality inspections for structural stability.
Chris Dumford is the senior materials consultant in our Cincinnati office and has been employed by Terracon for more than 32-years. Chris is an AWS Certified Welding Inspector and his duties include both NDT and visual inspection of welded structures and components as well as certification of welders and weld procedures. Chris performs metallurgical examinations, materials testing and fracture analysis of various components. His previous experience includes working for the military and within the nuclear power industry.