If correctly selected and positioned, the rubber fender unit(s) will absorb the kinetic energy of the largest, intermediate and smallest ships to use the berth.
The rubber units need to cope with different compression speeds, high and low temperatures, berthing and bow flare angles, and occasional or frequent use. They may need to resist shear or tensile forces. They must be reliable and work to full capacity when they are needed the most – during an abnormal impact.
1. Steel fender panels (frames)
These are complex steel fabrications and their design should only be entrusted to qualified structural engineers. Panels need to resist combinations of bending, shear and local buckling. There are many ‘limit state’ design codes (BS5950, etc) and finite element software packages able to determine these loads and stresses.
International Navigation Association recommends 12mm as the absolute minimum when exposed to seawater on both faces, 10mm for exposure to one face and 8mm for internal sections not exposed to corrosion. This means a panel should be a bare minimum of 160-180mm thick if standard internal steel channels are used to stiffen it. Bigger systems often need panels 250-400mm thick.
Paint coatings also vary in quality and no paint lasts forever; 10-15 years being typical. After this, the steel will corrode and weaken unless corrosion allowances are added. If corrosion allowances are not specified, they will invariably be ignored and the life expectancy of the panel will be drastically reduced. For cold water climates, a corrosion allowance of 3mm per exposed face might be suitable, much more where temperatures are higher and corrosion is greater.
Connections of the rubber fender and polyethylene (PE) face pads to the panel also need close scrutiny. Rubber fender fixing points should be locally reinforced and sealed to prevent water ingress if closed box panels are used.
Steel Panels
Steel Panels of Rubber Fenders are complex steel fabrications. They are connections of the rubber fender and the UHMW PE facing pad.2. Anchors and fixings
Any fender system is only as good as the weakest component. Calculations for loads should be presented, and fixings selected accordingly. In cooler waters, a galvanised fixing might be appropriate, but in warmer places, stainless steels are the only solution. Independent specialists like the British Stainless Steel Association suggest Pitting Corrosion Equivalent Numbers (PREN) of around 40 for highly corrosive environments like the Middle East and Asia. As a guide, 316 grade has PREN of 25-26 whereas 304 grades are below 19.
Mooring Bollards
In the maritime contexts in which the term originates, a bollard is either a wooden or iron post found as a deck-fitting on a ship or boat, and used to...
Mooring Ropes
Natural fibre ropes used to be the choice of impoverished sailors, but so little is made that it is now more expensive. It is hard, therefore, to justify...
Chains
Chains are used for two reasons – to suspend/support the fender or to control the deflection geometry during horizontal ...
Shackles
Shackles and other accessories are all referenced to the nominal chain diameter for equivalent strength and typically of larger diameter material.
U Anchors
U Anchor is an main accessory in marine rubber fender system. It is used to hold chains.
Bolts and Nuts
Bolts, Nuts and Washers are a set of fasten fittings. They are used as joint part between fender body and dock, steel panels and fender body, UHMW-PE facing pads and steel panels. Usually these fasten fittings are made of stainless steel, Q235 Hot galvanized.3. Low-friction facings
If minimum thickness or wear allowance isn’t specified, then competitive forces invariably mean pads of 30mm or less will be fitted to the panel. A 30mm pad with 3-4mm wear allowance may last less than five years. Increase the thickness to 40mm and wear allowance should be 8-10mm.
Only Ultra High Molecular Weight (UHMW)-PE pads should be used because they offer the best combination of price and durability. The ideal is to request a ‘double sintered’ UHMW-PE, which is not only economic, but has been work hardened for even better wear properties.
UHMW PE Facing Pad
UHMW-PE, Ultra High Molecular Weight Polyethylene, has become the material of choice for facing steel fender panels...
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