AB. The International Marine. Contractors Association. Guidance on. The Use of Cable Laid. Slings and Grommets bestthing.info IMCA M August . Reference(s). IMCA LR ; IMCA M Published: September Version: Rev. 1. Format: Download Contact us: IMCA Publications Team. The International Marine Contractors Association (IMCA) has IMCA M was first issued in August and has been revised for a variety.
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LR , M , SEL - Guidelines for lifting operations Rev • IMCA LR, M – Guidance on the Manufacture and Safe Use of Cable-. Purpose of this investigation. •. Type of splicing. •. Test data. •. Facts. •. Mind breakers. •. Proposal IMCA M January •. Draft IMCA M April CRAFTSM EN. Franklin Cable Laid Sling Table. Franklin Grommet Slings. Reference: IMCA M Hand Spliced Soft Eyes Each End I. Sling Diameter / mm .
Proper sling protection was essential. It was mentioned that the cost for fibre was still higher than steel. However, for competitive work rates fibre was more attractive. Re-use was also making fibre more attractive. High temperature operations were a slight concern for fibre — they had been used in the Middle East and had to consider strength loss due to temperature. Over time the Safety Factor SF has reduced — it started at 7 and was now reduced to about 3.
It was mentioned that it may go down ever further in the future.
Some issues that were still to be resolved included: Certification is not standardised Inspection and discard — existing guidance is not clear Connection of steel slings to fibre slings — should not be done due to internal torques and twists. This included defining Material Factor, bending effects over crane hooks especially DIN hooks which could damage both fibre and wire slings , re-use of slings, proof load test requirements and how to determine the correct skew factors.
Re-use of fibre slings had been performed. However, they involved the manufacturer for inspection before re-use, especially after reconfiguration or re-splicing. Damage to protective jackets could easily happen.
Can we repair on the vessel?
The International Marine Contractors Association
Clients could be concerned with damage to protective jackets. We needed guidance on how to deal with this. Adjustable fibre slings were discussed as beneficial within deck handling. Technically these were fit for purpose. Hence, they were deemed to be too high a risk to use. Sized at 24 x 18 x 25m, they required an asymmetrical lift under different lifting configurations where the head height clearance for lifting was very challenging.
Another difficulty was that the single hook became completely filled with rope. They needed to ensure that the ropes did not get crossed on the hook. Hooking on of the cargo was performed 22m above the deck within a limited access space, even with the required scaffolding. Onshore crane assistance was planned and required to assist with the task.
For Saipem this project involved the lifting of the upper structure of the floating wind turbine complete with blades attached and mounting onto the floating spar type bases. It was pointed out that the upper structures were to be lifted from the bottom, so the lift was potentially very unstable. The assembly site was in Norway where the S was to do the lifting.
Saipem worked with the manufacturer to determine the acceptable wind speed at m not the usual 10m used for offshore construction. Subsea contractors were normally limited by sea state, but not in this case. Wind speed was critical. Franklin Offshore had to manufacture the slings to very tight tolerances.
Slings were pre-stretched to bed in splices against the actual load that they would see. This was to ensure that the variation in the lifting slings was acceptable.
All this was required as when landing on the spar, it would sink approximately 11m. The complexity of these lifts was clear to all, hence a multi-disciplinary team had been working very hard on this — including the use of meteorologists.
Steel wires had had plenty of time for the standards to appear.
Fibre ropes behaved effectively the same as steel ropes. But product differentiation due to materials, weave, etc. Hence there was a need to rely on data-driven design methods. Samson believed that the whole rope needed to be broken, not just the strands. Elongation measurements were taken from real test data during the break tests. It was important to know where the bedding in process stopped.
In closing it was stated that in creating data-driven sling strength models they could provide assurance to operate at the designed factor of safety and satisfy end user risk tolerance requirements.
IMCA- M204 - Vessel Assurance
Initial slides on the physics of D:d that applied to everyone — wire, fibre, Samson, Cortland, etc. The test data curve showed a very similar curve to D:d for steel from DNV.
It was noted that proof loading did not really tell you much. In reality, it would not tell you your FoS. Compacted or deformed unit ropes are not allowed to be used. The breaking load of unit ropes up to 60mm diameter should be calculated in accordance with the method given in ISO and for larger ropes EN will be applicable see Appendix 1 for method of calculation. For these purposes, this is taken as 9. This bending factor will also be applicable for the bend of the sling eye, although this will often not be governing as the sling load will be divided over the two legs of the eye.
The eyes of a sling leg should be formed by the use of hand splices made in one of the following ways, or by another method which can be demonstrated to be as efficient. The core should be worked in with the splice and not cut out. The length of tails of outer ropes after the last tuck should be at least three times the diameter of the cable laid rope and the tails should be seized to the main body of the sling.
The method of splicing must be mentioned on the consolidation test certificate see Appendix 2. These tucks should be over and under against the lay of the rope, except that the first tuck only of any one unit rope may be with the lay.
The sixth tuck can be made with one half of the strands from the outer unit ropes. All tucks should be over one and under two. The minimum remaining undistorted sling length between the splices of both sling ends shall, in all cases, be at least 15d, where d is the nominal diameter of the cable laid rope forming the sling. If the sling body is to be doubled then this minimum length must be agreed by the interested parties, but should not be less than 15d.
A grommet contains one tuck splice diametrically opposite the core butt position. This core butt and tuck position should be clearly marked by red paint and should be positioned at approximately 0.
The grommet must never be bent at this marked position. Dimension h should be at least 2w. IMCA M 7 11 5. The difference in circumferential length between grommets of matched pairs should not exceed 1.
IMCA publishes guidance on the manufacture and safe use of cable-laid slings and grommets
The length of the circumference should be at least five times the cable lay length. Unless specified otherwise, when measuring actual grommet lengths, if pins are used, the pin diameter should be as per Table 2.
Diameter of cable laid rope Table 2 Pin Diameters Pin diameter mm mm mm mm mm mm mm mm If measurement under conditions different from the above is required, the customer should state the requirements on the order and the details should be shown on the certificate of dimensional conformity Appendix 3B.
For these purposes this is taken as 9. Note: Although the cross section of the grommet comprises a total of 14 ropes, the core section of the unit rope should be discounted in the calculation of the breaking load because the joint is butted and not spliced.
Note: Under no circumstances should the grommet contact any surface where the radius is less than 0. The actual unit rope breaking load should be equal to or greater than the calculated breaking load in accordance with paragraphs 2.
The following certificates should be issued for each sling or grommet and should be available to all interested parties on request: i Consolidation test certificate see Appendix 2 ; ii Certificate of dimensional conformity see Appendices 3A and 3B ; iii Certificate of examination see Appendix 4.
IMCA M 14 8 Identification and Marking Each completed sling or grommet should be permanently marked by the maker with a unique identification number, so that it can be identified with its Consolidation Certificate see Appendix 2. Each cable laid sling should also be marked with a longitudinal line to show its alignment when originally measured see paragraph 2. For a grommet, the core butt position and the tuck position should be marked by red paint see paragraph 5.
Competent person Designated person, suitably trained, qualified by knowledge and practical experience, and in possession of the necessary instructions to enable the required calculation of WLL and examination to be carried out.
Guidance on the manufacture and safe use of cable-laid slings and grommets
An inspection or thorough examination is carried out to identify damage or deterioration which affects fitness for use, such as: i broken or damaged wires; ii iii iv distortion of the rope crushing, kinking, etc. A thorough examination should be carried out: i at least once in every six months if the sling or grommet is in use; ii iii before putting the sling or grommet into long term storage; if the sling or grommet has been in store for more than six months and is being put into use.
Appendix 5 gives guidance on the assessment of the condition of the sling or grommet and on discard. A certificate of examination see Appendix 4 should be renewed after each thorough examination.The sling should be withdrawn from service and referred to an independent competent person for thorough examination, where pitting, arcing or marked discoloration due to overheating are identified.
For these applications, f is taken as not less than 2. Competent person Designated person, suitably trained, qualified by knowledge and practical experience, and in possession of the necessary instructions to enable the required calculation of WLL and examination to be carried out.
Localised breaks If there are three or more broken wires closely grouped. Damage due to weld arcing.