Although HMPE fibre cordage has been available for decades, the past few years have seen a dramatic increase in its use for mission-critical, heavy-duty applications, particularly in the energy sector. High modulus polyethylene, often referred to as HMPE, has one of the highest strength-to-weight ratios available; but in order to optimise that strength, the fibre’s vulnerability to abrasion and UV light must first be controlled.

The newest hybrid HMPE / polyester constructions have proven uniquely suitable to moor ultra-deepwater oil rig structures (both mobile and permanent), secure offshore wind arrays, and perform high-stakes, heavy lifting and lowering applications, including deepwater deployments and recoveries.

On land, this cordage enhances electrical line workers’ safety and efficiency, and enables utility companies to lift and transport equipment with unprecedented efficiency and precision.

In the time since the hurricane seasons of 2004 and 2005, which saw the uprooting of mobile offshore drilling units in the Gulf of Mexico, fibre engineers and rope manufacturers have developed better, safer, more reliable rigging systems for offshore facilities. Today, the worldwide political mood seems to favour aggressive oil and gas extraction with the caveat of safe and sustainable practices. Systems rigged using hybrid HMPE-PET lines are the cordage industry’s answer.

One of the great advantages of traditional steel chain and cable mooring systems is the extensive body of research on the materials’ characteristics. Also well-established are their limits. Corrosion and weight are two primary problems associated with steel wire and chain mooring systems.

Synthetic HMPE / polyester lines, which are expected to last 30 years or longer, offer a lightweight solution and distinct transportation, handling and safety advantages that set them apart from both steel and balanced polyester double braids. They also differ in key ways from 12-strand HMPE ropes designed for heavy lifting and lowering.

Though some of the newer, large-diameter ropes are impressive, the 12-strand constructions are vulnerable to cutting and abrasive marine forces, disqualifying them for mooring applications as well as certain undersea lifts. And for manoeuvring heavy objects, the stiffness and responsiveness of a parallel-core product becomes a necessity.

Saco, Maine-based Yale Cordage manufactures a double-braided HMPE-core, polyester-jacketed line called Unitrex XS™, which is dubbed the high-tech cousin of Uniline™ parallel-core polyester balanced double-braid product. Sensitivity to abrasion, historically the drawback of HMPE fibre in a mooring setting, is mitigated by parallel-core construction, an internal protective layer and high-tenacity polyester jacketing. Designed using the same construction that helped Uniline stand up to 25 years in a marina in South Freeport, Maine, while retaining over 80% of its original catalogued breaking strength, Unitrex XS has allowed for new and innovative applications.

As expected, performance data accumulated over the past decade has led to a continual increase in demand for HMPE-core products in deep-water and harsh-weather mooring environments. Also in a natural progression, a number of electric utilities have adopted Unitrex XS for the task of stringing overhead cables and setting poles.

Unlike steel wire, the lightweight material offers ergonomic advantages and its low conductivity and resistance to water absorption provide dual protection from electric conductivity and corrosion in harsh, unpredictable environments. Most importantly, it has the strength and manoeuvrability to safely and precisely handle tasks from line repair to mounting transformers or setting telephone poles.

It’s become a go-to material for one company, O’Connell Electric, which used it for the task of stringing a 17,000lb steel wire cable across a 1,400ft span of the Little Colorado River Gorge for ‘King of the Wire’ Nik Wallenda’s nationally-televised high-wire walk last year.

Though conductivity and water absorption weren’t considerations in this case, the team relied on their cable-stringing techniques and tools, including Unitrex XS cordage, to execute a fail-safe mission.

Similarly, when L3-Maripro Inc. was tasked with deploying deepsea regional scale nodes (RSNs) to specific, targeted location on the floor of the Pacific Ocean, the team chose Unitrex XS for the job. Due to the material’s reliability in deep waters, the lightweight that only synthetics can offer, and stiffness and responsiveness that more closely resembles the characteristics of steel wire than other synthetics, the hybrid HMPE / polyester product was determined to be the right choice to lower the sensitive, proprietary ocean research nodes safely and precisely into place.

The success of this and other extreme lifting operations led Yale Cordage to develop YaleTrex8™, a multi-part sling designed for extremely heavy lifts, made with Unitrex XS and offering lifting capacities of more than 500t. The product offers an unrivalled and markedly safer way to lift massive objects such as shipbuilding modules, bridge sections and large electrical transformers. Other manufacturers and engineers are using Unitrex XS in their own proprietary slings, opening a multitude of opportunities for the development of products to enhance the lifting and transporting heavy loads, both on land and undersea.