Section 6 Steel wire ropes

6.1.1 Steel wire ropes are generally to comply with the requirements of an International or recognised National Standard and are to be suitable for the use for which they are proposed in accordance with the manufacturer’s recommendations.

6.1.2 Steel wire ropes are to be manufactured at works which have been approved by LR. A list of Approved Manufacturers of Steel Wire Ropes appears in LR’s Lists of Approved Manufacturers of Materials. Proposals to use steel wire rope manufactured elsewhere will be specially considered.

6.2.1 The wire used in the manufacture of rope is to be drawn from steel manufactured by an approved process. It is to be of homogeneous quality and consistent strength and free from visual defects likely to impair the performance of the rope.

6.2.2 Ropes are to be constructed from individual wires with the following tensile strength grades, with the following range of strengths permitted, as indicated in Table 8.6.1 Range of wire tensile strength grades, N/mm².

6.2.3 The variation of breaking strength of individual wires for each of the above grades is to be in accordance with Table 8.6.2 Permitted variations in tensile strength.

6.2.4 The wire is to be galvanised by a hot dip or electrolytic process to give a continuous uniform coating. However, consideration will be given to the acceptance of non-galvanised and stainless steel wire in certain applications.

6.3.1 Each strand is to be uniformly made and free from slack wires. Core wires and fibre cores of strands are to be of sufficient size to enable the covering wires to be evenly laid.

6.3.2 The wires in a steel core are normally to be of similar tensile strength to that of the main strand, but wires of a lower tensile strength may be permitted. Fibre cores are to be of a suitable natural or man-made material.

6.3.3 The wire rope is to be uniformly made and the strands are to lie tightly on the core or on the underlying strands. The free ends of all wire ropes are to be secured against untwisting (serving). Wire ropes are to be thoroughly lubricated.

6.3.4 Wire ropes for running rigging are to be constructed of not less than six strands over a main core. Each strand is, generally, to consist of not less than 19 wires and may have a fibre or a wire core. Where the strand has a fibre core, the wires are to be laid around it in not less than two layers.

6.3.5 Wire ropes with four strands may be considered for running rigging, provided each strand is of an elliptical section and is constructed with at least 39 wires. Bending fatigue tests are to demonstrate that the fatigue life of the rope is at least equivalent to that of a similar six strand rope.

6.3.6 Wire ropes for standing rigging, guy pendants and similar applications are generally to be constructed of six strands over a wire core.

6.3.7 Four and six strand rope with Lang’s lay construction will not normally be accepted for the hoisting system of any lifting appliance. They may, however, be used in purchases which are rotationally restrained, e.g. crane luffing systems or in shiplift winch systems.

6.3.8 Lang’s lay construction is acceptable for high performance and compact multi-strand ropes as these ropes have good torsion resistance properties.

6.3.9 Types of construction and diameter ranges of standard round strand ropes are given in Table 8.6.3 Types of construction and diameter ranges - Round strand.

6.3.10 The construction and minimum breaking loads for some common rope types can be found in the current edition of ISO 2408.

6.3.11 Consideration will be given to the use of other constructions and nominal strengths and to the requirements for particular applications.

6.4.1 The lengthening by splicing of ropes for standing or running rigging is not permitted.

6.4.2 The following methods of forming eye or loop splices are acceptable:

1. Not less than three tucks with each whole strand of the rope and not less than two tucks with one half of the wires cut from each strand. In all cases, the strands are to be tucked against the lay of the rope.

2. Four tucks with the whole strands of the rope and one tuck with each alternate strand of the rope, made over and under against the lay of the rope.

3. A Liverpool type splice that has at least six tucks with each strand is only to be used where the wire rope is not subject to twisting, i.e. on span tackles, guys and pendants.

Other forms of splice will be accepted provided they can be shown to be as efficient, from all aspects, as those described above.

6.4.3 As an alternative to splicing; swages, ferrules, wedge and poured sockets, Flemish eyes or other types of acceptable terminal connections may be used. Such connections are to be approved, as required by Ch 12, 1.3 Steel wire rope 1.3.6 and Ch 12, 1.3 Steel wire rope 1.3.7.

6.4.4 Wire rope grips (e.g. U-bolt wire rope clamps or bulldog grips) are not to be used for forming a primary load bearing rope termination on any lifting appliance, with the exception of passenger lifts, where the higher rope safety factors, the use of several hoist ropes and the fitting of the safety gear make this type of termination acceptable.

6.4.5 Where wire rope grips are permitted to be used (e.g. passenger lifts and control lines, etc.), particular care is to be taken to ensure that the correct size clamp for the rope is used and that they are also fitted with the correct orientation, tightening torque and minimum number, in accordance with a recognised National Standard, or the manufacturer’s instructions. Terminations are to be tested to 2 x intended SWL.

6.5.1 Ropes constructed of stainless steel are not normally used for cargo handling operations but may have limited scope as running rigging for use on large commercial yachts. Where used, they are to be of ordinary or regular lay construction.

6.5.2 Stainless steel ropes are prone to pitting, crevice corrosion and stress corrosion cracking in a marine environment and when used are to be constructed from stainless steel wires with a minimum PREN of 30.

6.5.3 The use of stainless steel ropes does not remove the need for regular periodic rope inspections.