Document 3QLbaVbxnebwBvpRYqDQqzooJ

ROPE CHECKLIST Strength Stretch with load Permanent stretch Recovery from stretch Length Size Yardage Floatability Flexibility Twist direction and torque Flex life in bending Slippenness Texture Water repellency Hygroscopicity Ruggedness in shape Temperature resistance Friction melting Combustibility Sunlight resistance Marine growth resistance Rot resistance Chemical resistance Color Aging Contamination Uniformity Service Cost Toughness against wear Fic 26-1 --Factors that may be of significance when specifying rope for a specific use melting point can be secured Nylon, more than any other rope material, will absorb and store energy in the same manner as a spring This energy, released at break, will make the moving ends as danger ous as a projectile Caution must therefore be exercised when working lines around corners, capstans, timber heads, and the like Polyester makes probably the best generalpurpose rope available, especially for critical uses Polyesters stretch about half that of nylon, so energy absorption is also about half It is not weakened by rot, mildew, or pro longed exposure to sea water It retains its full strength when wet and shows bttle deterioration from long exposure to sunlight It has good resistance to abrasive wear and to most alkalis and acids, except benzoic acid Polyolefin ropes, in general, are strong and inexpensive, they float and are unaffected by water Polyolefins, like the polyesters, are not hygroscopic, therefoie, they do not shrink or swell with water The movement of crossed ropes, as well as othei types of abiasion, must be avoided because of a very rapid friction sawing which even modest loads will cause They are unaffected by rot, mil dew, and fungus growth and are highly re sistant to a wide variety of acids (except nitnc) and alkalis, as well as to alcohol-type solvents and bleaching solutions They swell and soften with hydrocarbons, particularly at temperatures above 150 F There are two types Polypropylene, with a specific gravitv of 0 91 and a softening point of 300 F, is made m several different size filaments and from film with or without longitudinal fracturing Polypropylene rope is about 50 percent stronger than mamla, size for size Pure polypropylene ropes have relatively poor ren dering properties Polyethylene, with a specific gravity of 0 95 and a softening point of 250 F, is char acteristically slippery and has very little springiness Stretch is low and strength is good It has a comparative low softening point and low coefficient of friction Composite ropes (combining several types of synthetic fibers or synthetic and natural fibers) are available in all sizes They result from attempts to give the surface of the rope or strand more wear resistance, internal tensile strength, or structural strength to re sist deformation Many of these ropes are made to match the requirements of specific jobs These ropes can be expected to perform to the ends their makers declare Other types of rope are available, but enjoy only a small percentage of the market for reasons of cost, limited use, or short supply These ropes include in various modifications paper, glass, acrylic, rayon, polyvinyl chlonde, fluorocarbon, rubber, cellulose acetate, and polyurethane Table 26-A lists breaking strengths and safe loads (working load limits) for mamla and synthetic ropes Fig 26-1 gives a check list of factors that may be of significance m a specific application Inspection New rope should be inspected along its entire length thoroughly, to determine that no part of it is damaged or defective, before being placed in service Any irregularity in the uniformity of appearance is evidence of pos sible degradation 713