Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Author contact details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv
Disclaimer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
Chapter 1 Introduction to fibre ropes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Ropes from ancient times to the mid-twentieth
century . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Advances since 1950 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.3 Rope issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.4 Diversity and choice . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Chapter 2 Ropemaking materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.1 Range of materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.2 Natural fibres . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.3 General-purpose synthetic polymers . . . . . . . . . . . . . . . 41
2.4 High-modulus, high-tenacity (HM-HT) fibres . . . . . . . . 47
2.5 Fibre mechanical properties . . . . . . . . . . . . . . . . . . . . . 52
2.6 Other fibre properties . . . . . . . . . . . . . . . . . . . . . . . . . . 70
2.7 Other rope components . . . . . . . . . . . . . . . . . . . . . . . . . 73
Chapter 3 Rope structures . . . . . . . . . . . . . . . . . . . . . . . . . . 75
3.1 Introduction to rope structures . . . . . . . . . . . . . . . . . . . 75
3.2 Formation of rope structures . . . . . . . . . . . . . . . . . . . . . 77
3.3 Laid rope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.4 Plaited rope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
3.5 Hollow braid rope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
3.6 Double-braid (braid-on-braid) rope . . . . . . . . . . . . . . . . 90
3.7 Braided rope with jacket . . . . . . . . . . . . . . . . . . . . . . . . 93
3.8 Solid braid rope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
3.9 Parallel strand rope . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
3.10 Kernmantle rope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
3.11 Parallel yarn rope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
3.12 Wire-rope type construction . . . . . . . . . . . . . . . . . . . . . . 99
Chapter 4 Properties of rope . . . . . . . . . . . . . . . . . . . . . .. . . 101
4.1 Rope dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
4.2 Strength and weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
4.3 Elongation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
4.4 Energy absorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
4.5 Fatigue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
4.6 External abrasion resistance . . . . . . . . . . . . . . . . . . . . . . 136
4.7 Friction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
4.8 Ultra-violet exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
4.9 Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
4.10 Chemical and biological attack . . . . . . . . . . . . . . . . . . . 139
4.11 Shrinkage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
4.12 Spliceability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
4.13 Knot retention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
4.14 Hardness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Chapter 5 Rope mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
5.2 Tension, torque, elongation and twist . . . . . . . . . . . . . . . 148
5.3 Predicting rope properties . . . . . . . . . . . . . . . . . . . . . . . 151
5.4 An alternative approach . . . . . . . . . . . . . . . . . . . . . . . . . 160
5.5 Bending stiffness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
5.6 Variability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
5.7 Fatigue and durability . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
5.8 Hockling and snarling . . . . . . . . . . . . . . . . . . . . . . . . . . 177
5.9 System effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
Chapter 6 Rope production . . . . . . . . . . . . . . . . . . . . . . . 185
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
6.2 Production of rope yarns . . . . . . . . . . . . . . . . . . . . . . . . 191
6.3 Strand manufacture . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
6.4 Production of three- and four-strand rope . . . . . . . . . . . 197
6.5 Production of braided rope . . . . . . . . . . . . . . . . . . . . . . 200
6.6 Production of low-twist rope . . . . . . . . . . . . . . . . . . . . . 207
6.7 Production of parallel-yarn rope . . . . . . . . . . . . . . . . . . 211
6.8 Post-production treatments . . . . . . . . . . . . . . . . . . . . . . 212
6.9 Quality considerations . . . . . . . . . . . . . . . . . . . . . . . . . . 212
Chapter 7 Terminations . . . . . . . . . . . . . . . . . . . . . . . . 215
7.1 Fibre rope terminations . . . . . . . . . . . . . . . . . . . . . . . . . 215
7.2 Splicing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
7.3 Splice mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
7.4 Mechanical terminations . . . . . . . . . . . . . . . . . . . . . . . . 226
7.5 Socketed terminations . . . . . . . . . . . . . . . . . . . . . . . . . . 229
7.6 Thimbles and pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
7.7 Wire rope clips and swaged sleeves . . . . . . . . . . . . . . . . 233
7.8 Cleats, bitts and bollards . . . . . . . . . . . . . . . . . . . . . . . . 233
7.9 Stoppers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
7.10 Knots, bends and hitches . . . . . . . . . . . . . . . . . . . . . . . . 234
Chapter 8 Use of rope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
8.2 Safe use guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
8.3 Rope uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
8.4 Guidelines for using rope . . . . . . . . . . . . . . . . . . . . . . . . 250
Chapter 9 Inspection and retirement . . . . . . . . . . . . . . . . . . . . . . . . 269
9.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
9.2 Basis for inspection and retirement . . . . . . . . . . . . . . . . 269
9.3 Rope materials and constructions . . . . . . . . . . . . . . . . . 270
9.4 Inspection and retirement programme . . . . . . . . . . . . . . 271
9.5 Used rope inspection and evaluation . . . . . . . . . . . . . . . 272
9.6 Disposition following inspection . . . . . . . . . . . . . . . . . . 274
9.7 Types and effects of damage . . . . . . . . . . . . . . . . . . . . . 283
Chapter 10 Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300
10.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300
10.2 Reasons for testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302
10.3 Safety in testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
10.4 Terminations for strength testing . . . . . . . . . . . . . . . . . . 306
10.5 Strength and elongation test equipment . . . . . . . . . . . . 307
10.6 Strength instrumentation . . . . . . . . . . . . . . . . . . . . . . . . 309
10.7 Elongation instrumentation . . . . . . . . . . . . . . . . . . . . . . 310
10.8 Strength and elongation testing procedures . . . . . . . . . . 312
10.9 Size, linear density, lay and braid cycle lengths . . . . . . . 315
10.10 Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319
10.11 Cyclic loading tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320
10.12 Flex fatigue testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
10.13 External abrasion resistance testing . . . . . . . . . . . . . . . . 325
10.14 Creep testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326
10.15 Hardness testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326
10.16 Testing for fibre properties . . . . . . . . . . . . . . . . . . . . . . . 328
10.17 Synthetic fibre identification . . . . . . . . . . . . . . . . . . . . . . 329
Chapter 11 Consumption, markets and liability . . . . . . . . . . . . . . . . . . . . . . 330
11.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330
11.2 Consumption of fibre rope . . . . . . . . . . . . . . . . . . . . . . . 330
11.3 Markets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332
11.4 Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333
11.5 Liability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
11.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336
Chapter 12 Case studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337
12.1 Diversity of ropes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337
12.2 Riser protection nets . . . . . . . . . . . . . . . . . . . . . . . . . . . 337
12.3 Deepwater moorings . . . . . . . . . . . . . . . . . . . . . . . . . . . 343
12.4 Supply vessel moorings . . . . . . . . . . . . . . . . . . . . . . . . . 357
12.5 Facing wires for pusher tugs . . . . . . . . . . . . . . . . . . . . . . 359
12.6 Parallel yarn ropes: antenna stays and other uses . . . . . 360
12.7 Kinetic energy recovery rope . . . . . . . . . . . . . . . . . . . . . 362
12.8 Failure and success with Kevlar aramid ropes . . . . . . . . 363
12.9 Investigating failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370
12.10 Climbing ropes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375
12.11 Sailing and yachting . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379
12.12 Mussel ropes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 386
Appendix I Quantities and units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 388
Appendix II Braid and plait terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . 392
Appendix III UK trade data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394
Appendix IV The theory of backtwist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396
Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 404
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 408
Preface
Has there been an engineering manual on modern fibre rope? The answer to this oft-asked question is ‘no’. As far as we know, the only comprehensive book on this subject was Himmelfarb’s (1957) The Technology of Cordage Fibres and Ropes; it focused on natural fibres, barely mentioned man-made fibres and completely omitted several modern types of rope construction. In the 1980s Stanley Backer of the Massachusetts Institute of Technology was funded by the US Navy to work on failure theories and mathematical modelling of rope structures. This stimulated his interest because of the complex nature of rope structures and led to several graduate theses under his guidance, in addition to the reports made to the US Navy, but these had limited distribution. Useful books on specialised applications are those by Smith and Paget (1966), and TTI and Noble Denton (1999).
The general development of the fibre rope industry, following the wide acceptance of synthetic fibres in the mid-1950s, has been extraordinary but has not been chronicled. In addition, the last two decades has seen considerable research directed towards improving utilisation of the newer, ultra high-strength fibre materials and expanding the applications of high-performance grades of older materials. Much of this has been covered in research reports and in conference proceedings, but not consolidated into any kind of comprehensive form.
To fill what we see as a void, this handbook has been produced to update the history of fibre rope technology, to describe the properties of popular modern ropemaking materials and constructions, to explain structural mechanics, to present an appreciation for usage, to suggest inspection procedures for used rope, to discuss testing, and, finally, to tell something about marketing and distribution.
We owe our thanks to the multitudes who have laboured in this unique industry over the centuries. The dramatic advances that have occurred in recent times are, in part, due to the vision and dedication of certain individuals and groups who we would like to recognise:
Chris Leech of the University of Manchester Institute of Science and Technology, who significantly advanced the mathematical modelling of rope structures. Stephen Banfield of Tension Technology International, who has provided leadership in a variety of industry-funded research projects and has been responsible for termination designs that have made certain important rope structures viable.
Mike Parsey of Marlow Ropes and Tension Technology International who, among other contributions, pioneered new rope constructions that were important in developing interest in deepwater mooring of oil production platforms.
Gale Foster of the Cordage Institute, whose leadership has led to important standards development for North American rope products and who has led the efforts to establish global harmonisation in the industry. Also, special thanks are extended to him for encouragement and review relating to this book. The fibre producers and ropemakers who have expended considerable effort to improve their products and to introduce new ones.
Many other manufacturers, academics and users of ropes have funded research or conducted trials with new products which have led to important advances. They deserve our appreciation.
The staff at Woodhead Publishing Limited have been unfailingly helpful. Our particular thanks are due to commissioning editor Patricia Morrison, her successor Emma Starr and review editor John Layton.