FIRST HEAVY LIFT SUPER FLY JIB WITH FIBRE ROPE STAYS

Transcription

1 FIRST HEAVY LIFT SUPER FLY JIB WITH FIBRE ROPE STAYS G. Wender, BigLift Shipping, the Netherlands W. van Zonneveld, FibreMax, the Netherlands M. van Leeuwen, Teijin Aramid, the Netherlands M. te Velthuis, Huisman Equipment, the Netherlands SUMMARY A 350mT Super Fly Jib was developed for BigLift Shipping to install two shuttle trusses in the harbour of Port Hedland, Australia. The biggest challenge within this project was to install this heavy piece of equipment within short notice and with limited tooling. A solution was found in light weight Fibre Ropes produced with endless winding technology. Figure 1: Installation of shuttle truss with use of 17m super fly-jib NOMENCLATURE EWR HLMC HMPE MBL SFJ SWL - Endless Winding Robot - Heavy Lift Mast Crane - High-Modulus Polyethylene - Minimum Break Load [mt or kn] - Super Fly Jib - Safe Working Load [mt] 1. INTRODUCTION For installation of the shuttle trusses with BigLift s Happy Buccaneer, more outreach and lifting height was demanded from her 700mT Heavy Lift Mast Cranes. This could all be achieved by installing a 17m Super Fly Jib on top of the original boom of the HLMC. With flyjib, requirements could be met, 36m outreach and 55m hook height above the water level, allowing a hookload of 350mT. Smooth and fast installation of this fly-jib was a significant part of the total project and therefore key within the design process. Figure 2: Installation of bridge modules with Happy Buccaneer

2 2. FLY JIB DESIGN Since the Happy Buccaneer is equipped with 2 off 700mT HLMC s installing the fly-jib s main components can easily be executed. When the fly-jib itself and the stay beam are fitted on; the wires have to be installed afterwards. This is a tough job because of tooling is limited onboard, working at height and the weight of conventional steel wire ropes and accompanying sockets is significant. The maximum SWL of the super fly-jib is 350mT on board the Happy Buccaneer and the SWL of the stays equals 240mT. Soon, it became clear that steel wire would be too heavy, not only during installation and de-commissioning, but also during transport of the stays. The fly-jib was designed to perform a dedicated job and with the use of steel wire the design was touching/passing the boundaries of the requirements. Another solution had to be chosen and this is where Fibremax was asked to provide a solution with their lightweight stays. 3. LIGHTWEIGHT FIBRE STAYS 3.1 ENDLESS WINDING TECHNOLOGY FibreMax cables are produced with endless winding technology which is a totally automated process of continuous winding of parallel strands of fibres around two end fittings until the right cable strength or required cable stretch has been reached. After the required length has been programmed, the EWR (endless winding robot) computer calculates the amount of fibres and the amount of loops required for the specified cable. During the winding process the EWR maintains an equal tension in all fibres with an accuracy of 0,1%. This results in the highest break load, lowest stretch and lowest possible diameter. It also ensures that cables are produced with high repeatability; when producing multiple cables FibreMax can guarantee that all cables will have exactly the same specifications. When the desired amount of loops has been reached the cable is compressed by a strong and lightweight wraparound tape to ensure minimal diameter and protection of the fibres. After this tape has been wrapped around the cable, another light, but strong, heat-shrink tape is automatically wrapped around the cable. These two layers of tape act as a particle filter layer to limit the amount of particles from protruding and destroying the fibres. After the cable has been sealed a bullet-proof braid of polyester, HMPE or aramid is applied to ensure protection against wear and abrasion. When needed the cable can be provided with a special low drag surface to reduce vortex-induced vibration (VIV). Because of their very light weight FibreMax cables already have a higher natural frequency than steel wire ropes. Figure 3 & 4: Endless winding technology 3.2 DESIGN CONSIDERATIONS First design was based on an open spelter socket end termination. Since FibreMax uses and endless winding production technology and potted sockets are not used, the open spelter socket is engineered in a different way than with steel wire rope. With the endless winding technology fibres are laid parallel in endless loops around two end terminations. To produce a cable of 9000kN with an open spelter socket FibreMax engineered two separate cables of 4500kN with special end terminations; when combined together they formed the required stay of 9000kN. As part of the certification process by Lloyd s Register and to obtain the final order FibreMax had to prove that the stay had a breaking strength of 9000kN. The first design was tested on a sample stay at Mennens in Dongen (The Netherlands) on their 13500kN test bench. FibreMax succeeded successfully for this break test. After some design considerations Huisman Equipment decided that a closed spelter socket would be a better solution. The open spelter socket created a sideways force on the end termination when under load. Due to this force there was a possibility that the stay couldn t rotate on the pin and cause damage to the stay or the flyjib. Another consideration was a possible skewed orientation of the end termination which could cause an unequal load distribution on the fibres. Since no risk had to be taken it was decided to use a closed spelter socket that immediately eliminated these risks.

3 This meant that the design of the end terminations had to be changed and another break test, witnessed by Lloyd s Register, had to be performed. Within a very short period of time FibreMax revised the design of the end termination and another test sample was produced. Again the sample was tested successfully at Mennens until break occurred. Manufacturing a parallel laid cable of 9000kN is not simply done by adding more fibres (more endless loops). Synthetic fibres are only strong in one direction, when pulled. Adding more fibre creates a high fibre stacking in the end terminations and because of the reaction forces creates a undesirable pressure on the fibres which could cause an early failure (breaking) of the entire cable in the end termination. The geometry of the end termination has to be properly defined to avoid these undesirable pressures. FibreMax has not only experience in defining the right geometry of the end terminations, it has also an in-house developed EWR 2.0 (endless winding) production method that makes it possible to manufacture cables with breaking strengths of more than 2500mT while maintaining the same production efficiency when manufacturing a cable of 25mT. Another consideration was on the choice of material for the steel parts of the end terminations. The fly-jib is constructed to work in a marine environment, therefore subjected to sunlight exposure, salt water and extreme temperatures. To prevent any corrosion taking place the steel part of the end terminations of the stays are constructed in stainless steel All materials had to be supplied with a 3.2 certificate because of the LRS certification process. Prior to production all individual material were stamped and documented by Lloyd s Register and surveyors of Lloyd s were present during the different steps of production. Figure 5: Fibre rope with end fitting Since the original design for the stays was based on steel wire some considerations on the geometry of the end terminations had to be taken into account, but were well covered during the engineering process. The endless winding technology allows FibreMax to produce cables with a length tolerance of 1mm, whereas for this project a tolerance of 50mm on each individual cable was allowed and a tolerance of 10mm length difference between two matching cables. Higher tolerances would cause undesired loading effects in the structure of the fly-jib. FibreMax was able to meet these specifications without problem. 3.3 ARAMID AS CONSTRUCTION MATERIAL For this application para-aramid was chosen as preferred fibre material. P-Aramid fibre Twaron is produced by Teijin Aramid, The Netherlands. To produce the material, Teijin Aramid produces dedicated monomers to obtain the right polymer material (aramid is an acronym for aromatic polyamide). The polymer does not melt, which makes the typical melt spinning process not an option. The fibres are therefore produced by dissolving the polymer in 100% sulphuric acid. After the spinning process, the fibres are extensively washed to make sure all acid has left the material. This procedure results in a material that has a very interesting set of properties, such as high strength for weight, chemical and heat stability and dimensional stability, even under high stress. It provides a very good protection against impact and can be recycled to pulp for braking pads. The latter enables the fact that in aramid production no waste is produced. From start it was obvious that aramid was the material of choice for the fly-jib stays. Especially since aramid fibres show negligible creep properties (permanent elongation under load) compared to other fibre materials. Both Huisman Equipment and BigLift decided that creep should be avoided in this application (exposure to higher temperatures increases the creep rate). Aramid is a very stable fibre and has proven its strength already in many applications for many years. Aramids are mainly known for their use in body armour, tire reinforcement and reinforcement of optical fibre cables. In fact aramid fibres are the most versatile high performance fibres and are being used in numerous applications. Already from the introduction of aramids, about 30 years ago, heavy lift cranes were considered as a viable application. Both for running ropes and for static cables for stays and rigging, aramids are being seen as the material of the future. However, to be able to answer questions about the expected lifetime of the fibres a lot of experience and test results are required. Teijin Aramid has therefore gathered a large amount of data from actual applications and laboratory tests. Combined with material science theories this know-how is applied to convince certifying bodies, engineers and end-users. This know-how is not only important for heavy lift applications, but also necessary for applications such as reinforced pipes and bottles, antenna guy wires, risers and umbilicals. The fact that FibreMax uses a fully automated process where the fibres are used in a parallel configuration contributes significantly to the way how applicable fibre know-how is in the final product. Due to the naturally strict safety and insurance regulations however, replacement of steel components with another material such as aramid, is not as obvious as

4 it seems. Guidelines often do not include other materials than steel as this was never desired. For these and other reasons the specific requirements from e.g. Lloyds on how the quality of the materials should be checked and validated are not aligned with the QA methods used in aramid production. For example the critical process parameters, the definition of a product batch and the number of bobbins of raw material per finished product are quite different from the regular steel wire based products. This required quite some cooperation from the manufacturers on one hand and Lloyds on the other hand. Due to dedication from all involved parties this process could be finalized with confidence and receipt of the required certificate from Lloyds. 3.4 BREAK LOAD TESTING AND LLOYD S CERTIFICATION As part of the certification process by Lloyd s Register (according to LRS Code of Lifting Appliances in a Marine Environment) [1] and to obtain the final order FibreMax had to prove that the stays had a breaking strength of 9000kN. The first open spelter socket design was tested on a sample stay at Mennens in Dongen (The Netherlands) on their 13500kN test bench. After pre-loading of the cable in a controlled sequence up to 75% of the breaking strength the cable was pulled to break. At an astonishing load of 9553kN the cable was still not broken, but the test was stopped to prevent damage to the test auxiliary hardware. When the cable was loaded for a second time it finally broke at 9134kN, still well over the required 9000kN. These results prove that due to the unique Endless Winding Technology of FibreMax it is possible to load up cables to 90% of the breaking strength without any problem. Figure 6: Fibre rope ready for load test Figure 7: Fibre rope after destructive load test

5 (worldwide) had an aramid cable been produced for such an application. The endless winding technology of FibreMax shows that it is possible to scale up from cables with just a few tonnes of breaking strength to cables with very high breaking strength without losing efficiency and with high repetition. 4. FLY JIB INSTALLATION 4.1 TRANSPORT OF MATERIALS Since all components where produced in Northwest Europe and installation was foreseen to take place in Australia, all parts had to be transported over more then nautical miles. A 40ft container was purchased to function as a flat transport base for the stays and small additional parts and equipment. Figure 8: Load test certificate The stays were originally engineered by Huisman in steel and the original rated breaking strength of these stays was 7200kN, based on a SWL of 2400kN and a safety factor of 3, as prescribed in Lloyd s Register of Shipping Code for Lifting Appliances in a Marine Environment (CLAME 2009) [1]. Since no specific design rules or experience exist for synthetic stays it was decided by LRS that an extra safety margin (uncertainty factor) of 1,25 should be added to the original 7200kN. Final breaking strength was set at 9000kN. This extra margin was only due to the few experience of Lloyd s Register with synthetic stays. The break load test at Mennens showed that aramid fibres are as strong as steel, but with significant reduction in weight up to 90%. Lloyd s Register witnessed not only the testing phase but was also present during different steps of the final production process. All materials had to be supplied with a 3.2 certificate. Prior to production all individual materials were stamped and documented by Lloyd s Register and surveyors of Lloyd s were present during the different steps of production. From the complete process Lloyd s Register gained a lot of experience on the use of synthetic stays which can be used in future projects and as a guideline to new rules. It was a big challenge for FibreMax to produce stays with such a high breaking strength. Never before Figure 9: Open top transport container 4.2 INSTALLATION AND LOADTEST Installation and handling of the fibre stays was even more successful then foreseen. A light mobile crane, some chain tackles and hand power was sufficient to attach the stays to their connecting points. Figure 10: Loadtest in Fremantle

6 After installation, a loadtest under class witness was required to gain certification. A pile of weight was constructed, using ship materials. A successful test with an overload of 10% as per class requirement [1] was performed for minimum radius to maximum outreach. During these test the stiffness of the stays was experienced for the first time and proofed to be very stable. Wilco van Zonneveld is a Mechanical Engineer from the HTS in Den Haag and since end 2008 holds the position of Business Development Manager at FibreMax. He s responsible for all technical and commercial support to customers worldwide and for development of new markets with Fibremax Endless Winding Technology. Matthijs van Leeuwen is a Chemical Engineer from the University of Twente and working for Teijin Aramid since 2006 as Business Development Manager for ropes and cables in the oil and gas industry. During this project he was responsible for providing the required Twaron fibre know-how for engineering purposes and for the Lloyds approval. Mathijs te Velthuis holds the current position of Section Head Mechanical Engineering at Huisman Equipment. He is responsible for the mechanical and structural design of the 350mT Super Fly Jib. Engineering of the installation of this fly-jib was also part of his scope. Figure 11: Fly-jib installed 5. CONCLUSION It was a correct decision during the design process to seek a lightweight solution for the stays. This was the key of success during installation and demobilization. The fact that Aramid fibres are produced already for over 30 years and proofed to be a stable product contributes to this success. 6. AUTHORS BIOGRAPHY Gem Wender holds the current position of deputy manager operations at BigLift Shipping. He is responsible for operational workflow of heavy lift operations. Managing preparations, leading the CAD department, review material purchasing. His previous experience includes Project Engineer at BigLift. In this position, he was involved in the flyjib project: engineering preparation, installation/demobilization, supervision of the project carried out with this flyjib.