This case study examines the practices of a major utility company in sourcing and maintaining synthetic ropes for pulling hard line conductor cables. Synthetic ropes made with high-modulus polyethylene (HMPE) fiber, such as Honeywell Spectra® fiber, offer the strength of comparable steel rope at one-seventh of the weight. When designed and maintained with the end use in mind, HMPE ropes enable faster, more efficient and safer operations.
There are more than 160,000 miles of electrical transmission lines located throughout the United States today. This electrical grid infrastructure continues to expand, and existing infrastructure is maintained and replaced by electric utility companies all over the country in order to continually provide reliable service to the millions of households and businesses dependent upon electrical power. The largest public power company, the Tennessee Valley Authority (TVA), is responsible for providing and maintaining reliable energy service to more than 9 million people in seven states. Created in 1933, TVA sells more than 171 billion kilowatt hours of power each year. As an industry leader, TVA prides itself on providing a safe working environment for its employees and the communities in which they work. TVA began using high-modulus polyethylene (HMPE) fiber ropes six years ago to pull hard line conductor cables, as they were safe, reliable and cost-effective. Recently, the company’s field operations began to lose confidence in the braided 12-strand HMPE ropes they use after experiencing inexplicable and untimely rope failures. This prompted TVA to review its overall pulling line operations in order to ensure employees could do their jobs in the safest way possible. The benefits of using synthetic pulling lines made of HMPE gel-spun fiber, such as Honeywell Spectra® fiber, is well documented in the utility industry. The key benefit of an HMPE fiber rope is it is approximately seven times lighter than steel wire rope, with comparable strength. The weight savings allows operators to eliminate much of the weight on their rigs, making the equipment and rope easier to maneuver and position in difficult environments. The rope’s light weight also allows the crews to avoid overweight permitting by saving a significant amount of weight on their trucks. The use of HMPE fiber ropes enables faster, more efficient and safer operations. This case study will examine the lifecycle and use of HMPE pulling ropes at TVA, which helped the company identify a better rope design and a more standardized approach to managing its rope inventory.