Belkasoft Live RAM Capturer

Nylon, Polyester, and polyolefin ropes are the major types of synthetic fibre ropes used.

Synthetic fibre ropes are used more often than natural fibre ropes for the following reasons.

• More is known about the properties of various synthetics.

Successful use of synthetic fibre rope depends largely on selecting the synthetic with physical properties and characteristics that most closely match the requirements of the job.

• Splices can be made readily in synthetic fibre rope and can develop nearly the full strength of the rope. Tapered splices are highly recommended for rope sizes with a 1-in. (2.5-cm), or larger, diameter.

Nylon rope:

• Nylon rope has over two and a half times the breaking strength of Manila rope and about four times its working elasticity. It is, therefore, well suited to shock loading, such as is required for restraint lines.

• Its resistance to abrasion is remarkably high in comparison to other ropes.

• Exposure to air produces little loss of strength over long periods of time.

• Since there is no swelling, wet nylon rope runs through blocks as easily as dry nylon rope.

• Although resistant to petroleum oils and most common solvents and chemicals, nylon's strength is affected by drying oils, such as linseed oil or the phenols. Nylon rope is also vulnerable to strong mineral acids, phenolic compounds, and heat.

• Nylon loses some of its strength at 300 F (150 C) and all of it at 482 F (250 C)-its normal melting point. Short of melting, most of nylon's strength is regained upon cooling to normal temperature. Nylon of a higher melting point is available.

• Nylon, more than any other rope material, will absorb and store energy in the same manner as a spring. When nylon rope breaks, this energy makes the rope's moving ends as dangerous as a projectile. Exercise caution, therefore, when working nylon lines around corners, capstans, timber heads, and the like.

Polyester rope:

• The best general-purpose rope available, especially for critical uses, is made of polyester.

• Polyesters stretch about half as much as nylon, so energy

absorption is also about half as much.

• It is not weakened by rot, mildew, or prolonged exposure to seawater. Polyester, also, retains its full strength when wet because it does not absorb moisture.

• It shows little deterioration from long exposure to sunlight and has good resistance to abrasive wear. Polyester is somewhat vulnerable to alkalis, but its resistance to ultraviolet light.

• It burns at about 480 F (250 C), and loses strength at

temperatures over 390 F (200 C).

Polyolefin rope:

• Polyolefin rope is also highly resistant to a wide variety of acids (except nitric acid) and alkalis, as well as to alcohol-type solvents and bleaching solutions. However, it swells and softens with hydrocarbons, particularly at temperatures above 150 F (66 C).

• The movement of crossed ropes, as well as other types of

abrasion, must be avoided because even modest loads will cause a sawing motion that leads to a built up of friction. Descriptions of two types of polyolefin ropes are given below:

• Polypropylene rope, with a specific gravity of 0.91 and a

softening point of 300 F (150 C), is made in several different size filaments and from film with or without longitudinal fracturing.

• Polypropylene rope is about 50% stronger than Manila rope,

size for size.

• Pure polypropylene rope has relatively poor rendering

properties. It burns at 330 F (166 C) and loses some strength at 150 E E Polyethylene rope, with a specific gravity of 0.95 and a softening point of 250 F (120 C), is characteristically slippery and has very little springiness.

• It is strong and has little stretch.

• Polyethylene rope also has a comparatively low softening point and low coefficient of friction.

Composite rope :

• Rope made by combining several types of synthetic fibres or by combining synthetic and natural fibres is also available.

• Composite rope results from attempts to give the surface of the rope or strand more wear resistance, greater internal tensile strength, or more structural strength to retain its shape. Composite rope can be made to match the requirements of specific jobs.

• To provide guidelines, working loads are tabulated for rope (1) in good condition,

(2) with appropriate splices in non critical applications, (3) under normal service conditions, and

(4) with very modest dynamic loads included.

• It is advisable to Select a higher working load only with expert knowledge of conditions and a professional estimate of the risks involved. Factors to consider include:

(1) whether the rope has been subject to dynamic loading or other excessive use,

(2) whether it has been inspected and found to be in good condition,

(3) whether it is to be used in the recommended manner, and (4) whether the application involves high temperatures,

extended periods under load, or obvious dynamic loading, such as sudden drops, snubs, or pickups.

• For all such applications and for applications involving more severe conditions of exposure, or for recommendations on special applications, consult the manufacturer.

• Many uses of rope involve serious risk of injury to personnel or of damage to valuable property. This risk is often obvious; for example, a heavy load supported above one or more workers. An equally dangerous situation occurs if personnel are in line with a rope that is under excessive tension. Should the rope fail, it may recoil with considerable force-especially if the rope is made of nylon. Workers should be warned against standing in line with the rope. In all cases where such risks are present, or if there is any question about the loads involved or the conditions of use, the SWL should be greatly reduced and the rope should be properly inspected and the manufacturer should be consulted for recommendations on working loads.

loading. The more rapidly or suddenly such actions occur, the greater this increase will be. In extreme cases, the force put on the rope may be two, three, or even more times the normal load involved, such as when picking up a tow on a slack line or using a rope to stop a falling object.

• Dynamic effects are greater on a rope with little stretch such as Manila than on a rope with higher stretch such as nylon. Dynamic effects are also greater on a shorter rope than on a longer one. The working load listed contains provision for very modest dynamic loads. This means, however, that when a working load has been used to select a rope, the load must be handled slowly and smoothly to minimise dynamic effects and to avoid exceeding the provision for them.

• Before placing new rope in service, thoroughly inspect its entire length to determine that no part of it is damaged or defective. Any irregularity in the uniformity of appearance is evidence of possible weakness. There is no agreement on what determines when a rope should be removed from service. Synthetic rope damage is not always visible.

• Every 30 days, under ordinary conditions, the rope should be inspected before taken in to use. The rope should be inspected much oftener if it is used in critical applications, such as to support scaffolding on which employees work.

• Inspection consists of examining the entire length of the rope, inch by inch, for wear, abrasions, powdered fibre between strands, broken or cut fibres, displacement of yarns or strands, variation in size or roundness of strands, discoloration, and rotting.

• To inspect the inner fibres, untwist the rope in several places to see whether the inner yarns are bright, clear, and unspotted. If exposed to acids, natural fibre ropes, such as Manila, should be

• Natural fibre rope loaded to over 50% of its breaking strength will be permanently damaged; synthetics loaded to over 65% may be damaged. Damage from overloading may be detected by examining the inside fibres. These will be broken into short lengths in proportion to the degree of overload. To make a good estimate of the strength of fibres, scratch the fibres with a fingernail-fibres of poor strength will readily part. This "fingernail test" is a quick test for chemical damage.

• If the diameter of a rope is worn more than 5 % the rope

should be replaced. In small ropes (up to 1/4in., 19 mm, in diameter), surface wear that has progressed to the centre of the twisted element (yarn) may account for more than an 80% loss of the rope's strength.

• In ropes with a 3/4-1n. (19-mm), or more, diameter, surface wear may destroy the strength of the cover yarns, yet not affect the original strength of the core yarns. The remaining strength of the rope will be in the proportion that the core yarns are to the original total of yarns. If fibre samples can be secured from the rope, an estimate of the rope's strength can be made. Manually break the fibre samples, and estimate the distribution of fibres in a cross section, quartered to allow for twist configuration.

• Due to slippage on a supporting surface when under high

tension, synthetic ropes sometime melt on the surface and form a skin. This skin is the evidence of wear. Rope, using multi- filament synthetic fibre on the surface, will often "fuzz." This is due to minute fibre breakage. If a rope is very fuzzy, replace it and look for the source of abrasion.

Care of Rope Being Used :

• If possible, do not drag rope since this wears away the outer fibres. If a rope picks up dirt and sand, abrasion within the strands of the rope will rapidly wear it out.

• Handle twisted rope so it retains the amount of twist (called balance) that the rope seeks when free and relaxed. If rotating loads and improper coiling and uncoiling change the balance, restore it by properly twisting the rope at either end. Severe unbalance can cause permanent damage; localised over twisting causes kinking or hocking. Kinking strains the rope and may over stress the fibres. It may be difficult to detect a weak spot made by a kink.

• To prevent a new rope from kinking while it is being un -coiled, lay the rope coil on the floor with the bottom end down. Pull the bottom end up through the coil, and unwind the rope counter clockwise. If it uncoils in the other direction, turn the coil of rope over, and pull the end out on the other side.

• Avoid sharp bends over an unyielding surface since this causes extreme tension on the fibres. To make a rope fast, select an object with a smooth round surface of sufficient diameter.

• If the object does have sharp corners, pad the corners.

To avoid excessive bending, use sheaves or surface curvatures of suitable size for the rope's diameter.

• Splice lengths of rope that must be joined. Do not knot them. A well-made splice will retain up to 100% of the strength of the rope, but a knot retains only 50%.

• Thoroughly dry out rope that has become wet; otherwise, it will quickly deteriorate. Do not allow wet rope to freeze. Hang up a wet rope, or lay it in a loose coil in a dry place until thoroughly dry. Rope deteriorates more rapidly if it is alternately wet and dry than if it remains wet.

• Do not use wet rope, or rope reinforced with metallic strands, near power lines or other electrical equipment. Use of such