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IMCA Guidance used in Franklin Offshore’s latest record breaking feat

The Franklin Offshore Group can rightly call themselves record breakers, for they have secured not one, not two, but three Guinness World Records. Most recently Franklin Offshore Europe BV – the Group’s largest business unit, based in Rotterdam in The Netherlands – has broken all previous records with the MERLION TR King Cobra cable-laid grommet slings Sling identification numbers : SL 8635 & SL 8534).

It is now acknowledged as the world’s largest cable-laid grommet sling by rope diameter at 462mm; and has the world’s highest Calculated Grommet Breaking Load (CGBL) for a grommet sling at 17,484 tonnes (based on the Minimum Braking Load (MBL) of the unit rope: 1,550 Tonnes x 12 x 0.94). What’s more, IMCA guidance played an important role in its production.

Built by Franklin Offshore Europe for Heerema Marine Contractors, the sling is being used to carry out one of the world’s heaviest lifts using the world’s largest crane vessel – the 119,000 tonne ‘Sleipnir’. All work was undertaken in strict compliance with ‘Guidance on the manufacture and safe use of cable-laid slings and grommets’ IMCA LR 008/M 170 Rev 1.1.

The guidance is referenced in the witness’s verification statements as “Technical Reference for the sling CGBL: IMCA LR 008, M179 Rev 1.1. April 2019”. The tensile grade of the unit rope is 1960 Grade steel wire rope.  David Glennie, a Director at Franklin Offshore, made the comment that a good steak comes from good meat, so a good sling can only come from a good rope. After a global review of the rope makers then by QA/QC Audit acceptance FOE placed the order with KISWIRE based in Malaysia who manufactures the NEPTUNE brand of steel wire ropes. The rope was strictly manufactured in compliance to API Specification 9A and subject to the quality control of both KISWIRE and DNV- GL Certification. The rope diameter was 154 mm with a 1, 550 Tonne minimum breaking load. From acquisition of the contract and ordering of the wire rope to completion of the grommet took the best part of six months.

“We are delighted that IMCA LR 008, M 179 played such a key role in the production of this huge cable laid grommet,” IMCA’s Technical Director, Mark Ford explained. “It was fascinating getting feedback from David Glennie, and his colleagues on the effectiveness and value of the guidance. After all, this was no normal cable-laid rope grommet sling, it is gargantuan!

“Some of their findings, particularly relating to pin size and formulae will certainly be included in our next revision of the IMCA guidelines. As far as pin size was concerned our guidance had only gone as far as determining a required pin diameter of 1000mm for a grommet with a diameter of 376-500m – we’ll think bigger in the future! Ingenuity won the day for Hans Coenen the operations manager who designed, and Franklin produced, a steel collar to increase the sling radius to prevent sling damage.

“Their project confirms that the IMCA guidance document really does tick all the boxes. This is a huge feather in the cap of the work group that initially wrote the guidance in 2005 and the similar work group that reviewed it in 2016 and opted to include additional construction methods to align with current codes; and to amend formulae. That was followed by a complete review in 2019 when it was decided no changes were required. The feedback from Franklin is essential for the next review and revision.”

As David Glennie said: ”Compliance on the sling manufacture to the IMCA guidelines ensures a high quality safe sling produced.  to a historical trusted formula for a safe lifting.

The principal challenges the Franklin team incurred, apart from those that were COVID-19 related, concerned the huge area in terms of length and height they needed for creating SL 8653 and for manoeuvring the rope over and under the tube, and around the pillars.

As David and Hans explained: “Success was all about accurate calculation – that in its turn determines time and cost. Each unit rope was 867m with a combined weight of rope and reel of 90 tonnes. The unit rope Minimum Breaking Load exceeds 1,550 Tonne. The distance between the floor and the forming tube was critical for the reel had to go over and under it. Our challenges on production of such a large slings was the upgrade in heavy duty pillars, and sling handling in a safe manner with our 200 tonne capacity multi wheeler.

“Six overhead cranes in our cable laid runway production facility was used for the project to hold the massive sling weight. The under and over, under and over operation took about four normal working days just to complete the forming of the grommet. Then the tube had to be removed. This involved two days of manual labour with big hammers, forklift trucks and force playing their part. Our 200-tonne multi wheeler was used to move the slings to prevent damage.

“Lessons learned? It is quite rigid but be extremely careful, will work against you!”

The images show the enormity of the task – proof that a picture is indeed worth a thousand words!

Franklin Offshore’s world records

Before the claim could be sent to the Guinness World Record offices Franklin Offshore invited three independent witnesses to review, check and confirm three vital measurements – the cable-laid rope diameter; the calculated grommet breaking load; and the length of the sling (56,169m). The verification role was undertaken by DNV GL Technical Surveyor, Mr Arjen van der Van and Technical Expert, Mr Willem Jacob van der Velde who were witnessed undertaking measurements and calculations by lawyer Mrs Roos Jonkmans of Dingemans Vanderkind Advocaten.

In 1992 Franklin Offshore International Pte Ltd (Singapore), at the Group’s headquarters, started the Guinness World Record ball rolling (in the days when it was a record in the ‘Guinness Book of Records’) with the largest cable-laid rope, it had a 22-inch diameter and a rope breaking strength of 11,000 tonnes.

In June 2003 Singapore was responsible for yet another record when they produced the world’s longest grommet sling measuring 110m (360.8 ft) long with a diameter of 192mm (7.55 inches) and a calculated grommet breaking load of 3,070 tonnes.

“What a long way Franklin have come as far as those statistics and that record is concerned,” said Mark Ford. “We congratulate them on a job well done!”

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