MARINE CIVIL ENGINEERING
BETTER BOLLARDS With proper specification, testing and tapping into smart solutions today’s marine bollards can contribute a lot to safe and efficient vessel berthing. John Bensalhia reports
8 Bollard load testing underway in the port of Southampton, UK
While ongoing influences such as bigger ship sizes, higher demand for cargo and challenging weather conditions add extra pressure on marine bollard systems, technological breakthroughs have resulted in more advanced products such as smart bollards. However, let’s backtrack four years. In discussing regulations with respect to the design and use of heavy-duty marine bollard systems, Erik Broos of the Port of Rotterdam delivered a paper to the PIANC World Congress on the loadings that multiple lines impose on bollards. Ben Simpson, Business Development Executive, Fendercare Marine, takes up the story. “BS 6349-4 suggests that a maximum of two ropes from the same vessel should be considered, but we know that this is rarely the case. Onboard ship the design of the mooring equipment is based around the minimum breaking load (MBL) of the mooring line with a design factor of 1.25. The winch brakes are set at between 50 and 60 per cent of the MBL of the line. We know the design criteria based on the provisions within the relevant parts of BS 6349. “The actual load imposed by the mooring line,” Simpson elaborates, “will vary with the material from which the line is made and the angles through which the load is applied. Most conventional mooring lines are elastic, to an extent, so the shock loads are absorbed by the rope. Where the situation becomes very unclear is when mooring lines from different vessels are placed on the same bollard. These ropes may have very different characteristics and as such, apply their loads to the bollard in very different ways.” Simpson notes that there is a trend towards vessels using HMPE mooring lines which are, to all intents and purposes, inelastic as wire rope and should be used in conjunction with mooring tails of a more elastic material such as nylon. “However,” he says, “there are instances where mooring tails,
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for whatever reason, are not used, leading to a shock load that may be applied to the bollards. At what level will depend on the accuracy of the winch brake setting if indeed the lines are still on the winches.” Simpson adds that nowadays there are more requirements and specifications for independent bollard testing for new and existing bollards on quaysides: “This is so the client understands the loads that can be placed on existing bollards and that bollards that have been recently supplied can be validated.” Fendercare in partnership with Associated British Ports (ABP), has identified, designed and engineered a rigorous testing regime in order to demonstrate each bollard would be capable of holding the safe working load within the terminal. “By carrying out FEA analysis and destructive and non-destructive testing, we can provide confidence that the bollards are able to sustain and endure the working loads of the large vessel docking on the quayside.” THE CASE FOR TESTING UK-based Bollard Proof, a specialist bollard testing company, has recently tested bollards in Belfast, ABP Immingham and Southampton, Grangemouth, Rotterdam, Antwerp, Marseille, Corsica, Martinique and Guadeloupe. The testing included corroboration of in-house testing of smart bollards with internal and external load sensors. Generally, taking the testing route can deliver both greater understanding and ultimately knowledge of whether a bollard system is ‘man enough’ for the intended role. Bollard Proof points out that both old and new bollards can be tested. “With existing facilities, bollards might be so old that load capacity data may not exist,” says Rob Gabbitas, Technical Sales Manager. “Bollard Proof,” he elaborates, “can test and
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