A properly maintained wood utility pole can last 35 years or longer, according to the U.S. Forest Service, which estimates that more than 160 million wood poles are in service in North America alone. But oftentimes, the service life of a wood pole is cut short by natural enemies, such as woodpeckers, termites, rot, fire, high winds and excess loading. For that reason, steel and concrete poles have been incorporated into the power grid. And slowly but steadily, FRP composite poles, typically pultruded or filament-wound hollow tubes, are making their mark in the utility industry. That mark tends to be increasingly durable, with an estimated service life of 80 years.
The American Composites Manufacturers Association (ACMA) Utility and Communications Structures Working Group (UCSWG) has done extensive research and developed strategies for promoting FRP poles and crossarms to utilities, public utility commissions and others who specify and purchase these products. The group’s primary objective is to convince users to evaluate composites based on life-cycle costs rather than initial purchase price, according to Brian Lacoursiere, chairman of the working group and senior VP sales & engineering Chicago-based FRP pole supplier Duratel.
Composite utility poles were first installed during the early 1950s in Hawaii, where termites make short work of wood poles, giving them an average eight years of service life, relates Lacoursiere. “Those FRP distribution poles, which didn’t have any UV protection as we know it today, were taken out of service after 50 years. It wasn’t for structural reasons, but because of fiber blooming—the fibers started protruding through the surface and aesthetically didn’t look good,” he notes. “Today, composite pole manufacturers incorporate multi-faceted UV protection in their products, and that’s why we’re confident of the 80-year life.”
Power distribution poles range in length from about 35- to 50-feet and are produced in sections or as a single piece in various strength classifications. Transmission line poles are stronger and longer, up to 130 feet. Duratel, which launched its pole in 2008, offers one-piece products ranging from 35- to 75-feet in 11, 12 and 14-inch diameters. Plans are to extend the product line to as long as 110 feet. The poles, which are pultruded for Duratel by Bedford Reinforced Plastics, come off the pultrusion line at about a foot per minute for the 12-inch diameter, notes Lacoursiere.
Duratel poles, produced using polyester resin and E-glass, weigh about two-thirds less than wood. A 40-foot Duratel pole weighs 300 pounds. vs. about 1,000 pounds for wood. The Duratel products feature UV inhibitors throughout the resin and a protective veil cloth on the surface. The company sees its 14-inch diameter pole as its entrance into the transmission market.