Utility Rope Constructions
Sterling Rope Sep 18th 2024The choice of material is not just a technical detail—it’s the foundation upon which strength, flexibility, durability, and performance are built. Understanding the properties of these materials is essential, as they directly influence the rope’s resistance to abrasion, moisture, UV exposure, and load-bearing capacity. The characteristics of these fibers combined with the construction used, dictate a rope's suitability for specific applications.
The choice of material is not just a technical detail—it’s the foundation upon which strength, flexibility, durability, and performance are built. Understanding the properties of these materials is essential, as they directly influence the rope’s resistance to abrasion, moisture, UV exposure, and load-bearing capacity. The characteristics of these fibers combined with the construction used, dictate a rope's suitability for specific applications.
Rope Materials
Polyester—A synthetic polymer with lower elongation, lower water absorption and a higher resistance to chemicals and UV than nylon. Melting point 255°C (491°F).
Nylon—A synthetic polymer offering more elongation and a higher abrasion resistance than polyester, however, it is less resistant to chemicals, UV light, and water absorption. Melting point 218°C (424°F).
Polyolefin—A synthetic polymer made from olefins. The most common of these being polyethylene (PE) or polypropylene (PP). Polypropylene is sometimes used to bring the weight of a rope down, or if used exclusively, multi or mono filament polypropylene can be used to create floating ropes for water safety/rescue. Melting point 130-170°C (266-338°F).
Aramid—A class of synthetic fibers derived from aromatic polyamides, including
Technora, Kevlar, and Nomex that pound for pound are five times stronger than steel* (*comparing strength on a weight-to-weight basis). Slightly reduced ultraviolet (UV) radiation resistance compared to polyester and nylon, and it can be self-abrasive. Melting point 500°C (932°F).
Ultra-High Molecular Weight Polyethylene (HMPE)—Includes Spectra and Dyneema fiber. This lightweight fiber has super-high strength and abrasion resistance
but at a lower melting point. Good for use where heat from friction is not involved. Melting point 148°C (297°F).
Rope Constructions
Kernmantle
Climbing
The mantle (cover) of this rope is woven tight to provide protection for the load-bearing core (up to 70%) strands, which are not braided (parallel). Core strands can also be twisted like a slinky to add elasticity, providing manufacturers a lot of flexibility to manipulate the finished product based on intended use. Popular for ascent in SRS climbing. Arborist ascent lines of this construction are considered “core-dependent kernmantles.”
Solid Braid
Rigging & Pull Lines
Made up of 12 large strands, arborist-grade solid braid lines are woven tight to keep a round shape under tension, a process that’s made eye-splicing nearly impossible... that is, until Grizzly Splicing® came along. Solid braids tend to be bulky for their strength but have less tendency to twist than other braided lines. Generally used for rigging
or pull lines.
Double Braid
Climbing / Rigging
This braid inside a braid remains round under tension and provides a high strength-to-diameter ratio. Generally, core and cover share loading equally, making for significantly stronger ropes even in smaller diameters, Useful for climbing and rigging. Double braids are useful for low-elongation climbing and rigging. A tight rigging version (Super Braid) is available for greater dirt resistance when natural crotch rigging, and a loose rigging version (Stable Braid) that is spliceable and best for block and tackle use. Many climbing lines these days are double-braid construction, often with urethane coatings and similar wear resistance. Because of how they are constructed, double braids are likely to milk.
16-Strand
Climbing
This abrasion resistant rope construction presents a thick mantle (cover) around a small interior core bundle that helps keep the rope round under tension and makes it easy to tie. The thick mantle provides all of this popular climbing line’s strength while the core keeps it round. Because the cover bears the bulk of the load, inspecting these lines is easier and more consistent than
with other lines.
Hollow Braid
Slings & Fixed Lines
Another 12-strand construction but woven with considerably less tension, leaving the center loose. These lines can easily accommodate a hand splice. Their loose weave allows these ropes to “flatten” under load. Good for slings and line stringing. because they tend to snag or pick when
run over a rough surface and flatten
without a core.
3-Strand
Moderate Load Rigging
Twisted constructions are abrasion resistant but a poor choice for climbing due to their bumpy surface and tendency to rotate (ravel) under tension. Relatively less expensive than other lines, they can serve as natural crotch rigging lines with moderate loads where high elongation is not a worry.
Download the Sterling Utility Rope Reference Guide
This PDF file (~22MB in size), serves as a comprehensive reference guide for Sterling's utility and industrial ropes, detailing their specifications, applications, and custom options.
INSPECT YOUR ROPE
Climbing and technical rope work expose ropes to abrasion, fatigue, sunlight and constant loading. Severe falls, lack of protection over an edge, exposure to excessive temperatures, chemicals or improper use will shorten the life span of any rope.
REVIEW
Inspect your rope to be battle-ready every day. Run the entire length of rope through your hands after every use to feel for changes in the rope’s diameter or texture. Visually inspect for changes in color or for excessive fraying and core exposure.
You’re looking for signs of the following:
• Fraying
• Softness or stiffness
• Exposed cores
• Glazing or hard spots
• Lack of uniformity in diameter,
color or texture
• Termination damage (sewn/ spliced eye)
RETIRE
Know when to retire your rope. A good rule of thumb is that at any time if you are unsure about your rope and its condition and feel the need to ask for someone else’s advice about it, go ahead and retire it.
• Extensive Use: Up to 1 year
• Regular to occasional use: Up to 5 years
• Rarely used or new: Up to 10 years