BS EN ISO 9554:2019 pdf free.Fibre ropes – General specifications.
4.2 Construction and structure 4.2.1 Laid ropes Unless otherwise specified, 3-, 4- and 6-strand laid ropes shall be Z-twist (right-hand lay), their strands S-twist and their roping yarns Z-twist. 4.2.2  Braided ropes The 8-strand braided ropes shall consist of four S-twist strands and four Z-twist strands arranged so that S-twist strands alternate (individually or in pairs) with Z-twist strands (individually or in pairs). The 12-strand braided ropes shall consist of six S-twist strands and six Z-twist strands arranged so that S-twist strands alternate (individually or in pairs) with Z-twist strands (individually or in pairs). 4.2.3 Double-braided ropes A double-braided rope shall consist of a number of strands that are braided to form a core, around which additional strands are braided to form a sheath. The core lies coaxially within the sheath. The number of strands varies, based upon the size of the rope.4.2.4 Covered ropes A covered rope consists of a core protected by a non-load bearing cover. A parallel rope construction is a covered rope where the core consists of a number of sub-ropes. 4.2.5 Strands Each strand shall consist of an equal number of rope yarns sufficient to provide the characteristics specified in the International Standard for the relevant product. For ropes of reference number 36 or higher, the number of yarns in each strand may differ by one yarn or +2,5 % from the intended number of yarns in the strand. The ropes and their strands should be continuous, without splice for standard delivered lengths or shorter lengths. However, some lengths or methods of manufacture impose limitations. To overcome these limitations, strand interchanges can be used, these shall be in accordance with 4.4.3. Yarns may be joined as necessary. The strands can be assembled yarns. 4.2.6 Lay length or braid pitch The manufacturer shall establish the lay length or the braid pitch of the rope according to its intended use, or based upon the purchaser’s acceptance. NOTE For a given reference number of rope, the smaller the lay length or braid pitch, the harder the rope will be. This hardness can affect the estimated breaking strength of the rope.BS EN ISO 9554 pdf download.