Twisted Ropes can be recognized by their spiral shapes. They are made by twisting together bundles of individual yarns to form strands, which are then twisted together to form the rope. Twisted ropes are easily spliced, but have inherent torque and therefore a tendency to kink up and rotate under load.

Braided Ropes come in many variations and braiding patterns, but always consist of bundles of fiber which are formed into strands and then woven together by passing each strand over and under the others.

Cancord primarily manufactures braided ropes. Some of the different braided ropes we manufacture include:

• Diamond Braid ropes are formed by rotating half the yarn strands in one direction on the braider, while the other half rotate in the opposite direction. These cords may be hollow, or they may have a center core of parallel fibers. These ropes tend to be a little flatter than other braided rope constructions.
• Double Braid ropes are constructed from an inner hollow single braided rope (core) which has another hollow single braided rope constructed around its exterior (skin). The end result is a rope within a rope. Both the skin and the core share the load on the rope, but not necessarily in equal amounts. These ropes are generally very flexible, strong and pleasant to handle. They are easily spliced. Caution must be exercised where double braid ropes are run over pulleys, through hardware, or in any situation where the outer rope may slide along on the inner rope and bunch up. This condition, often called “milking”, will result in a dramatic loss of strength by causing the entire load to be applied to the inner core. These ropes are also referred to as “Marine Ropes”, “Yacht Braid” and “2 in 1”.
• Kernmantle ropes are made by braiding a cover (mantle) over a core (kern). The core may consist of filaments of fiber lying essentially parallel inside the rope, or it may be twisted or braided into little bundles. The ropes are designed so that the inner core is taking most (often all) of the load, with the outer cover serving mainly to protect against abrasive action, dirt, and UV rays. All other types of rope have the load bearing fibers exposed and therefore deteriorate more rapidly. These ropes are exceptionally strong and durable, and can be made to have very low elongation. All kernmantle ropes have some stretch. However, static ropes are designed to minimize the amount of stretch, whereas dynamic ropes have relatively more stretch.
• Solid Braid ropes are made by braiding 12, 18 or 20 strands in a reasonably complex pattern with all the strands rotating in the same direction on the braider. The center of the rope may contain a filler core. These ropes maintain their round shape and therefore work very well in pulleys and sheaves. They tend to have high elongation but generally have less strength than other constructions. They cannot be spliced. These ropes are also referred to as “Sash Braid”.

Broadly speaking fibers can be divided into two categories – natural and synthetic. Most ropes today are made from synthetic fibers because they offer far superior performance in terms of strength and durability. Natural fiber ropes have a tendency to deteriorate as a result of rot and mildew, particularly if stored improperly. Natural fiber ropes should not be used in life critical applications.

Cancord manufactures rope from the following fibers: Cotton, Dyneema®, Kevlar®, Nylon, Polyester, Polypropylene, Polysteel^TM, and Technora®

Download a PDF of rope fiber properties here.

A quality braided rope will have a smooth, uniform appearance when new. When purchasing a new piece of rope, look down the length of the rope for possible quality concerns such as broken yarn filaments, looped or pulled strands, uneven yarn color, or any other irregularity.

Broken Yarn Filaments most likely indicate the use of improperly maintained machinery. The result is lower overall rope strength and premature wear.

Looped or Pulled Strands are the result of poor quality braiding, yielding a rope in which all of the yarn strands are not working together equally. This will result in lower strength and premature wear. Looped strands may also snag on anything in the surrounding environment, causing further unnecessary wear and damage to the rope.

Uneven Yarn Color or Sheen most likely indicates the manufacturer has used inferior yarn or clearing lots of yarn. Many manufacturers do this to reduce costs. However, it can result in a variety of problems including reduced or inconsistent strength and premature wear.

Inconsistent Diameter occurs as a result of poor braiding. It may indicate problems with the core of the rope, or the balance of the skin and the core. It will result in lower breaking strength and difficulties if the rope is run through any hardware.

Dirt on new rope, often in the form of grease or oils spots, is an indication that the manufacturer is not committed to quality and inspection.

Cancord ropes are manufactured using only premium quality yarns. We have an ISO 9001 quality control system, with many checks and balances in place to ensure you are getting only the highest quality product.

Rope should be stored in a clean, dry, well-ventilated environment, away from direct sunlight, extreme heat, and chemicals.

While there is not a universally agreed-upon shelf life for unused nylon and polyester ropes we suggest a 10 year maximum for ropes that have been properly stored. Exposure to heat, ambient moisture, UV, exposure to higher or lower temperatures and chemicals will reduce the shelf life of the rope.

Even among rope manufacturers, there is not a definitive set of rules to be used in determining when a rope should be removed from service. However, the following is a list of generally agreed upon guidelines. When in doubt, it is always best to be conservative and replace the rope in question or downgrade it to a non-critical application.

Visual Inspection of the rope may reveal many signs that the rope has been weakened and should be retired. These include:

• Evidence of broken fibers or significant abrasion – Minor abrasion to the skin of the rope may not affect its performance. However, if the core of the rope is exposed or the diameter of the rope has been reduced anywhere due to damaged or cut fibers it is absolutely essential that the rope be replaced.
• Evidence of burns or melting – This may be caused by either abrasion or exposure to heat. Signs of melting suggest the rope has been compromised, and should be retired.
• Evidence of dirt – Kernmantle ropes are designed to protect the load bearing fibers from dirt and grit. However, excessive dirt may indicate that the rope has been weakened by the dirt particles abrading the individual fibers in the rope. This is of particular concern if the dirt cannot easily be cleaned off the rope, or if it seems as though the dirt has penetrated through to the core of the rope.
• Evidence of oil or grease – If the exposure is recent and minor, it may be possible to wash the rope using a mild detergent. However, extreme caution should be exercised, as oil often contains other contaminants, which may chemically damage the fibers in the rope.

Quoted breaking strength of rope is usually the optimum strength achieved under laboratory conditions, in accordance with prescribed test procedures, on new rope, pulling at a slow, steady rate in a straight line. Real life applications normally involve many different types of forces and factors which will cause the rope to fail at much reduced loads. Accordingly, the safe working load of any rope is much lower than its nominal strength.

The following article reprinted with permission from Cordage News, a publication of the Cordage Institute provides a good overview of factors to consider when determining the safe working load of the rope.

TOTAL POTENTIAL LOAD (TPL) is the weight to be lifted, towed, restrained, suspended, or secured, not just in a static condition, but in a dynamic condition. Examples: the jerking of a weight being lifted, the heaving of a vessel, the slalom of a water skier, the falling of a body, the swaying of scaffolding, the tethering of a balloon, the wind pressure on antenna guys, a truck being towed out of the mud, and a boat being towed through waves – these and many other situations like them produce dynamic forces with a total potential load that may well exceed, sometimes substantially, the static weight of the load, and this must be taken into account.

WORKING LOAD LIMIT (WLL) of a size and type of cordage or rope must be determined by the user (engineer, operator, or manufacturer).

A DESIGN FACTOR (DF) must be selected based on the TPL, the degree of risk to life, limb and property and the conditions of use. This, in turn, is used to establish the WLL using the formula Minimum Breaking Strength divided by the Design Factor (WLL = MBS + DF).

For critical applications a Design Factor greater than 12 may be necessary. Users must determine the DF as they are the only one who can assess service conditions and establish operating procedures. The TPL applied to a cord or rope should never exceed the WLL. If uncertain, a qualified engineer should be consulted.

Cordage Institute Standards now show a range of Design Factors (5-12)* for selection, and values at the high end of the range, or larger, should be used when:

• Smaller ropes are used, because they can be more severely damaged by cutting, abrasion and sunlight.
• Loads cannot be accurately predicted.
• Operators are not trained.
• Operations and use procedures are not well defined and/or controlled.
• Inspection is difficult, infrequent or performed by inexperienced persons.
• Extreme dynamic loading (shock loads) are possible.
• High temperatures are present.
• Strong chemicals are present.
• Ropes are kept in service for long periods.
• Rope will be under tension for long periods (creep).
• Ropes will be subjected to bend ratios under 3:1.
• Ropes will be used over sheaves at less than recommended D/d ratios.
• Knots are used (strength is reduced up to 50%).
• Death, injury or loss of valuable property may result from failure.

*Cancord Note: Some Standards such as CAN/ULC S555 and NFPA 1983, require a DF of 15:1

The actual breaking strength of any individual rope is determined by pulling the rope at a slow, steady rate in a straight line, to the point of destruction.

The rated minimum breaking strength of a rope is determined using the “3 sigma” method. This means the minimum breaking strength is calculated by taking the mean or average breaking strength of 5 rope samples, and subtracting 3 standard deviations. Statistically, this creates a confidence level of 99.87% that any sample of rope will actually be stronger than the quoted minimum breaking strength.

All ropes, particularly those used in life critical applications should be kept clean and free of dirt, chemicals and other contaminants to prevent damage and wear that will reduce the strength, effectiveness, and durability of the rope. Where ropes have been exposed to chemicals, excessive dirt or other contaminants, we recommend discarding the rope, or downgrading it to a non-critical application.

We recommend the following when washing synthetic rope:

• Any particularly dirty or mud caked rope should be rinsed with water. A soft nylon bristle brush can be used if required.
• The rope can be soaked in a tub of water with a mild detergent such as Zero that is safe for washing the type of fiber your rope is manufactured from (e.g. nylon, polyester). Alternatively, the rope can be washed in a commercial washing machine using cold water. It is a good idea to run the machine through an empty cycle first to make sure it is free of any contaminants or residue from harsh detergents.
• By looping the rope into a daisy chain, or loosely bundling it in a large mesh bag prior to washing in a machine, you will help prevent the rope from tangling or getting caught in the machine. A front loading washing machine is best, as the agitator in the middle of standard washing machines can cause damage to the rope by abrasion.
• Rinse the rope in a washing machine.
• The rope should be hung to air dry in a cool, shaded place away from the UV rays of the sun or fluorescent lights. A rope must never be dried in a clothes dryer as the temperature in the dryer can be high enough to damage the rope.

A Personal Escape Rope is a one-time use, single person lifeline that is carried as a bail-out rope in dangerous situations. A good Personal Escape Rope will balance strength, heat resistance, abrasion resistance and handling characteristics.

Cancord’s Personal Escape Rope does just that. It is a kernmantle construction with a Technora® skin to protect the load bearing core fibers of the rope. It has a minimum breaking strength of 3,500lb which exceeds the NFPA requirements for Personal Escape Ropes. Our Personal Escape Rope is light weight and heat resistant (skin to 500°C, core to 245°C) with exceptional handling characteristics.