by Manila Cordage Company
Rope Selection: Which type of Rope will serve you best?
In your selection of the best rope to serve your needs, knowledge of the various types of rope available to meet different conditions is important. In determining the rope best suited for your requirements, the following factors are of special importance:
Know your rope requirements
- Strength lifts the load and does the work. It takes good fiber or filaments to give full strength.
- Abrasion Resistance assures extra life on pulleys, winches and other wearing or torsion conditions
- Water Repellency keeps rope from swelling when wet, prevents it from becoming stiff and unmanageable.
- Flexibility makes rope agile and easy to handle under all working conditions.
- Safety is of particular importance in falls, slings, hoisting, mooring and towing lines.
The correct size is important. Using undersized rope causes undue strain on the rope. Proper selection of the right rope size is the greatest factor in getting full use and long life from your rope. In addition to size, other factors such as type of lay and special fiber treatment (for Manila ropes) will determine the selection of rope. Most industries making regular use of rope have selected certain types as best suited to perform specific jobs. In some cases, special purpose ropes have been developed to meet particular needs. Generally, the proper size and type of rope can be specified from your past experience and the recommendations of your supplier.
Manco can makes 3- Strand, 4- Strand, or 8- Strand Plaited Ropes.
- 3-Strand ropes are preferred on most applications because of its flexibility, knotability, and ease in handling. They come in an easy-to- splice medium lay, however can be ordered to conform to specific lay requirements either softer or harder.
- 4-Strand ropes have a slightly firmer lay and provides a rounder rope with more outside surface and more traction on sheaves and objects to be turned or gripped. It is available in various core constructions depending on the rope's application. 4-Strand Manila ropes are approximately 7% heavier than 3- Strand and have a breaking strength approximately 5% less.
- 8-Strand plaited ropes have four left-hand laid strands and four right-hand laid strands, paired off parallel and woven together. Used mostly for marine applications, its neutral (or balanced) construction provides excellent hockling resistance. It is available in 5" to 15" circumference (or 1-5/8" to 5" diameter).
The standard package(s) are coils of 600-, 720-, and 1,200- feet wrapped in polycloth and lashed. Coils can be boxed in 25-, 50-, and 100- Pound cartons (for ropes 2-1/4 inch circumference and smaller). Ropes are also available in Coilettes of 50 feet and 100 feet, for 1-1/2 inch circumference and smaller. Non-standard lengths may be produced on order. The maximum length of a coil will depend on the size requested for.
All Natural Fiber (Manila) Ropes are lubricated with a water repellent treatment that resists moisture, mildew, and rot. The lubrication also guards against internal chaffing and wear. Upon request, ropes may be treated with Copper Quinolinolate, Copper Napthanate, Tar, Graphite impregnated, or Tallow treated. These treatments are generally for the added protection of fibers against rot and mildew.
Proper Use of Rope
Rope Care and Safety
- INSPECTION. New rope should be thoroughly inspected throughout its entire length before it is placed in service to determine that no part of it is damaged or defective. After it is placed in service, rope should be inspected at least every thirty days under ordinary circumstances; more often if it is used to support scaffolding or other supports upon which men work. If it is exposed to acids or caustics, it should be inspected daily. Inspection should include examination of the entire length of rope for wear, abrasion, broken or cut fibers, displacement of yarns or strands, discoloration or rotting. To inspect the inner fibers, the rope should be untwisted in several places to make sure the inside yarns are bright, clear and unspotted. The specification tables show breaking strengths and safe working loads. Rope loaded to over 75% of its breaking strength will be permanently injured. Damage from this cause may be detected by examining the inside threads which will be broken to an extent governed by the amount of the overload. Such damage may also be determined by the reduced diameter of the weakened section of the rope. Care should be taken to prevent kinking a rope. Even a moderate strain may over-stress the fibers at the point of the bend, producing a serious defect and one that may be difficult to locate.
- CARE OF ROPE. If rope becomes muddy or dirty, it may be washed with cold water and moderate hose pressure, but never with seam. Any grit or dirt that remains may be shaken out after the rope has dried. The use of wet rope or rope reinforced with metallic strands is dangerous near power lines and other electrical equipment. A wet rope should never be left where it may freeze. With proper care, lubrication other than that in the new rope is unnecessary. Sharp bending of the rope around objects too small for the rope, or over sharp corers should be avoided because these cause extreme tension or abrasion on the fibers/filaments. Be sure the bend is sufficient for the rope size; sharp corners or rough surfaces should be padded.
- EASIER HOISTING WITH LESS EFFORT NEEDED. Tackle lifts extra weight, but use the proper sheave size. Blocks and tackle reduce the power needed to hoist or pull a given load. The mechanical advantage to be gained will vary with the number of sheaves employed in tackle combinations. The illustrations and data represent standard practice in the use of block and tackle. The selection of correct rope size for specific applications is an important consideration for maximum efficiency and dependability.
- ROPE SLINGS. Small angles increase rope stress. Allow for sling angles. The breaking strength of rope is based on direct pull along a single length of rope. When slings, using two or more legs to carry the load, are properly employed, the rope's safe working load is substantially increased. However, as illustrated below, the load factor on each leg of the sling is greatly increase as the sling angle becomes smaller. Therefore, the use of slings requires certain precautions as well as a knowledge of safe working loads permissible. For best results, sling angles should never be more than 90 degrees - rarely less than 45 degrees.
- SPLICE ROPE FOR PERMANENCE. A splice is stronger than a knot. The strongest way to join two ropes, or to make a sling or endless rope, is to splice it correctly. Even the most efficient knots will reduce rope strength to as much as 50%, while a carefully made splice may have up to 95% of the strength of the rope being spliced. A short splice gives the strongest coupling however, it doubles the rope size and is not suitable where rope must run through pulleys or sheaves on a block. For such purposes, a long splice, with up to 90% strength efficiency, is used.
- GOOD ROPE CARE - BETTER ROPE SERVICE. or the service that should be expected from good rope, and for the safety of men and materials, rope should be handled and used with care. By following these points in rope selection, handling and storage, it will remain dependable and safe over long periods.
- SELECT BEST ROPE FOR THE JOB. Economy as well as service depend on the right size and quality for the work. Allow a safety factor of at least five to determine safe working load for new rope. As rope ages, the safety factor should be increased.
- REMOVE FROM COIL CORRECTLY. Always take rope from coil in this way to avoid distorting the lay of the rope. First, lay the coil flat with inside end of rope nearest the floor or deck. Loosen lashings and coverings. Then reach down through center of coil and pull rope up through from inside of the coil.
- STORE ROPE PROPERLY. Rope should always be dry before storing; storing wet rope causes mildew and rot. A cool, dry room with free air circulation makes ideal storage. If necessary to store on metal or concrete floors, protect the rope with planking to prevent contact with the floor.
- REVERSE ENDS OF ROPE. Changing ends of the rope regularly when used in tackle, permits even wearing and assures longer useful life. If a short section shows undue wear or damage, cut out the worn section and splice the rope for best service. Then make sure that the cause for the excess wear is corrected.
- KEEP ROPE CLEAN. Dragging rope on the ground or over rough, gritty surfaces allows abrasive particles to work into the rope and weaken the fibers. If rope becomes muddy or dirty, it should be washed and dried thoroughly before storing.
- KINKS CAUSE ROPE FAILURE. Prevent kinks which cause permanent damage and weakening of the rope. If kinks should form, or if rope is continually twisted in one direction, as over a winch, remove kinks or restore balance in the rope by throwing in twist in opposite direction.
- PROTECT ROPE FROM CHEMICALS. Acids and their fumes, alkalis, oils, paints and barn-yard mud are injurious to vegetables fibers and will quickly damage rope. protect from these agents wherever possible and remember that clean, dry rope is the best assurance of long rope life.
- AVOID SUDDEN STRAINS. Jerking or sudden strain may cause failure of a rope normally strong enough to handle the load safety. A steady, even pull will assure full strength from rope. This is especially important when using slings or tackle which may multiply strain and power.