Rubber fender1- definition Rubber fenders are mainly used as “bumpers” to absorb collision energy during contact between the vessel and docks or vessel and other vessel in the maritime industry. For many, they might not be aware that massive sea vessels are embedded with rubber fenders on the outer surface of the vessel. These fenders. Rubber fenders are also installed on docks.
Solid rubber fenders have been used for ages since they are readily available and are considered long lasting. The main objective of the rubber fenders on the dock is to absorb collision energy during the berthing process. This in return protects both the ship and the dock after collision. Rubber fenders come in different forms including, pneumatic type, CO-type, SC-type, GD-type and many others.
All these types of rubber fender are unique in their own way and come with different specifications and uses as discussed below.Fenders typesThere are many different types of popular fenders. Type of fenders used are basically dictated in a project by project basis to optimize performance over the product lifecycle. Some of the most popular types are arch fenders, cylindrical fenders, supercell fenders, cone fenders and more. Different types of rubber fenders are more suited for different situations and uses. To find out more about the types of fenders1-Cone rubber fenders: Also referred to as Type CO fenders, they endure severe shear external force by making effective use of its conical body shape.
With its high elasticity levels, they are more often used in big port construction.cone fenders are an improved version of Cell Type Fender recently introduced and recommended for all type of applications including high tidal variation sites. This advanced feature of lesser height of fenders improves material handling capabilities of Deck / Vessel Cranes which reduces overall cost of the project. Due to the geometrical shape of the fenders it can deflect more, and it can absorb more energy from any direction.
Maintaining reaction force, but doubling energy absorption, can be achieved by using two identical cone fenders in a back-to-back arrangement. To distribute the reaction force, cone fenders are typically supplied with large fender panels, which keep the hull pressure low. Cone have good energy absorption to reaction force ratio (E/R); Integrated and fully-embedded fender flanges make assembly & installation simple; Good shear force resistance due to the large diameter of the fender flanges; large fender footprint with good force distribution could lead to relative light panel construction. FENDER MARINE cone rubber fender adopts tapered rubber with a steel frame at the head. This new structural design increases the design compressive deflection from 52.5% to 70%, on the condition that the reaction force is not increased. This type of rubber fender lightens the structure of a dock and thus reduces the construction cost of a dock.
Therefore, a cone rubber fender, one of the best rubber fenders, is an ideal replacement of super cell rubber fenders. FENDER MARINE cone rubber fender is suitable for the docks that requires low reaction force and high energy absorption, the docks that requires low surface pressure of the ship’s panel, off-shore open berths and large docks like oil wharf and container terminal, as well as all places that are suitable for super cell marine fender. CharacteristicsHigh energy absorption with reaction force ratio (E/R)Outstanding energy absorption per fender weightHigh allowable static load of fendersHigh shear stability to enhance angular performanceHigh durability as the internal stresses are dispersed throughout the fender bodySophisticated and optimized fender geometryOptional overload stopperCELL FENDERSFENDER MARINE Cell fenders are mostly installed for docks (Dock medium type to VLCC) where Reaction Force is an important criterion. Among all types of fenders, Cell fenders offer minimum reaction per ton-meter energy absorbed. The very geometrical shape gives it sturdiness, shear resistance, compact structure and the capacity to absorb energy equally from all directions.
The Cylindrical buckling column absorbs axial loads effectively and buckles radically. This results in multi directional dispersion of energy. Cell fenders are the most durable rubber fenders available and are currently the largest molded fenders made. 2000-2500 mm high cell fenders are typically used for LNG berths. To distribute the reaction force, cell fenders are typically supplied with large fender panels, which keep the hull pressure low.
Our Cell Type rubber fender is installed on docks to absorb the collision energy between ship and dock at the time of berthing. In comparison to common marine fenders, the design compressive deflection of FENDER MARINE Cell rubber fender is increased by 13%, the energy absorption is increased by 17%, and the E/R is increased by 15%, on the condition that the reaction force is not increased. With higher E/R, this marine fender can be used for off-shore docks, especially suitable for dolphin wharf. This super cell rubber fender has no impingement steel frame at the head, which greatly reduces the surface pressure. The surface pressure can be controlled below 25 tons per square meter,2-“Wing” DO Rubber fenders: An improved design derived from the original D-Fender, this shape offers greater stability and maintains high durability.
It can be found on boats, marine assets, floating structures etc. It is not a very popular option compared to other fender types, but it does what it does well. They are also used in the general framework in wharf. wing fenders are compression molded fenders and are generally used on tugs, boats and ships. It is easy to install and replace.
It has excellent sea water resistance and resistance to ozone ageing and ultraviolet rays. This Wing Type fender is used to absorb the berthing energy during mooring or berthing to protect the ship and the dock from being damaged. It is suitable for various docks, wharfs sides. It has higher energy absorption than D type rubber fender. It features higher installation strength and long service life. This rubber fender is suitable for frame type docks.
3- Arch Fender.the most popular marine fender systems in the world. arch fender provides incredible shear performance, making it suitable for vessels with high allowable hull pressures arch fenders can be used with limited space or during situations with highly restricted conditions. Different dimensions (width, length, height) are chosen based on specific project applications that best suits the berth structure.
Arch fenders have a better Energy / Reaction force ratio and recommended for all types of applications. The very shape of these fenders helps to dissipate the stress evenly. These Compression Molded fenders are very easy to install and are maintenance free. Generally our Arch fenders are preferred for small to medium range Vessels. Arch Type rubber fenders are installed on docks and structures to absorb the collision energy between ship and dock during berthing. There are two types of Arch fenders; High reaction force type and Standard reaction force type. The design compressive deflection is 50%. This rubber fender features low reaction force and high energy absorption.
It is of reasonable structure, long service life, firm installation and easy replacement.arch fenders were introduced to improve upon the performance of cylindrical fenders. Arch fenders have a better Energy / Reaction force ratio and recommended for all types of applications. The very shape of these fenders helps to dissipate the stress evenly. These Compression Molded fenders are very easy to install and are maintenance free. Generally, our Arch fenders are preferred for small to medium range Vessels. Arch Type rubber fenders are installed on docks and structures to absorb the collision energy between ship and dock during berthing. There are two types of Arch fenders; High reaction force type and Standard reaction force type.
The design compressive deflection is 50%. This rubber fender features low reaction force and high energy absorption. It is of reasonable structure, long service life, firm installation and easy replacement. 4-Unit Element Fender: One of the most durable type with a versatile modular system. It can be installed horizontally or vertically on quay walls to suit a use.
5- Cylindrical type CY: Cylindrical shaped fender offers great versatility to accommodate all sizes of ships makes it a one of the most commonly used marine fender system. One unique advantage over other types is its ability to be installed diagonally, in addition to vertical or horizontal fitting. The cylindrical fenders can be easily mounted on the hull of the ship with a longitudinal chain. The fender can be supplemented by webbing straps or sleeved chains which fit in special grooviest ends of the fenders can be tapered to get a better connection to the hull. Cylindrical fenders can be attached to a wide variety of structures and in different manners. Installation is relatively simple, and they can be mounted horizontally, vertically or diagonally using chains or rods.
Cylindrical fenders can be provided in specified lengths and the ends can be beveled6- “D” type fender: There are 3 main types of “D” rubber fenders with differences in the inner hollow shape. DD comes with a D-shaped inner hollow Provided with a D-shaped inner chamber; DC comes with a O-shaped inner hollow; while Solid-D is entirely solid (O-shaped inner chamber). DS fender. Without an inner chamber. These fenders are popularly installed on smaller port walls and on boats/small ships. D fenders can be fitted by means of bolts and or strips in various manners: horizontally, vertically or diagonally. The mounting holes required are made through the side or through the top and bottom of the fender. D fenders can also be produced vulcanized with required radiuses, which allow them to be fitted properly to a circular bow or stern.
D fenders can be provided in specified lengths and the ends can be beveled.D Fenders can be pre-curved, chamfered and drilled to aid installation at a relatively low cost and can also be cut to the length required. They provide an excellent barrier against damage from all sizes and shapes of vessels. They are ideal for smaller quays and wharves serving fishing boats, tugs, barges and other work craft. D Fenders are also commonly used on pontoons and on inland waterways for lock protection Fenders are also called Extrusion Fenders. Extrusion is a manufacturing process involving pushing unvulgarized rubber through a special die to form a constant cross-section profileD Fenders Core Attributes are ?Ideal for smaller quays and wharves?Easy to install with a flat bar down the bore?Can be supplied in long lengths and be cut to length, angle cut at the ends”Roller” type: Specifically designed for entrances of docks and narrow canals, the roller design facilitates ships into space-restricted waters, by avoiding the vessel from crashing into the walls. Its main function is not about energy absorption, instead its main function is to “guide” the vessel. We have seen even wheels be utilized as rollers.
Keyhole” version: The outlook of the keyhole fender looks quite similar to the square type fender. The hollow part in the middle is of a key-hole shape. Depending on requirements, it can come with UHMWPE pads, or have a grooved/flat surface. It has high resistance towards abrasion and UV. MARINE Key Hole Fenders are used as an alternative to W-Fenders in case of extreme loads. The Key Hole Cross Section is very tough but can be curved around the hull. Fixing /Mounting is very simple with this type of fender. Keyhole fenders are the most versatile bow, stern fenders used on the Tug Boats and small Port Crafts/Ferries.
They offer maximum protection to the Tugs/Ferries with its typical profile and load absorbing capabilitiesW” version: Another popular choice for tug boats due to its ability to fit the form of the boat stern/bow. FENDER MARINE “W” Type Fenders are installed in to the bow and the aft portion of the ocean-going tugs, to protect the hull of the vessel, gainst the damages caused during pushing and Pulling operations/ towages. These fenders are installed in similar manner as those of Key Hole Fenders. With 50% design compressive deflection, this kind of W – rubber fender can effectively buffer the collision between docks and ships. W fenders have with high energy absorption and low reaction force. This type rubber fender is installed on Ship front area to protect the Ships from being damaged at the time of berthing.
M FENDERS.FENDER MARINE “M” type marine fender is used to absorb the berthing energy so as to protect the vessel or the dock from being damaged during mooring or berthing. It features high energy absorption, low reaction force, reasonable structure, easy installation and maintenance.Life Evaluation of Rubber Marine Fender Rubber fenders are always in contact with the corrosive sea water. Therefore, sufficient maintenance is required in order to have long lasting rubber fenders. The main key to marine fender maintenance lies in the anchor maintenance.
Anchor, made of galvanized iron, is used to attach fenders onto the pier wall. Following installation, anchors and fenders do not require any special treatment. However, the anchors need to be periodically checked to make sure that they are still in a good condition, for instance, the anchors are not rusty and still in their perfect shape (no breakage). Rust weakens the strength of the anchor, which can yield the fender to partially or even fully collapse from the pier wall. On the other hand, the rubber fender itself does not need special maintenance as the formula of the rubber contain antioxidant and antiozone to protect the rubber from oxidation and degradation due to ultraviolet radiation and ozone.In conclusion, the maintenance of marine fender depends on the maintenance of the anchors.
It is true that anchors are only the accessories of the fender; however, they are as important. Therefore, to have a long lasting marine fender system, these two components must be monitored continuously.The average life span of the CSB fender is 20 to 30 years. Although it is uncommon for the old fender to be sent to the manufacturer for a compression test, the authors took this opportunity to collect the records. Figs.
2, 3 ; 4 show the profile of the performance where the Y-axis is the non-dimensional reaction force (=Measured reaction force / Catalogue value of reaction force at 25% deflection). Fig.2 illustrates fenders smaller than 1000mm in height (;1000H), Fig.3 illustrates fenders between 1000 and 2000mm and Fig.4 illustrates fenders over 2000mm. The fenders are old and most of the initial test data before delivery has been lost therefore the catalogue values were used.
Note that standard production tolerance is ±10% so each plot has ±0.1 variance in Y-axis. It is evident that the data spreads further in the smaller fender. 1000H after 32 years and 40 years both displayed severe cracks on their bodies when they were compressed. 800H after 25 years showed uneven buckling and the fender top had slid sideways with the reaction force dropping after 20% compression. The reasons for differences of aging impact by size are as follows: •smaller size fenders have more aging of oxidation from the surface; •smaller size fenders have more effect from surface damage such as cracks to the performance relative to larger sizes; and •larger fenders tend to be used by larger vessels and more tugboat assist, therefore the control of berthing man oeuvre is improvedRubber material for fenders is a mixture of natural rubber (NR) and styrene-butadiene rubber (SBR) which increase its modulus over time. So, the reaction force is xpected to increase by years in service. Fig.
5 shows the reaction force rate (= Measured reaction force at 25% deflection / Catalogue reaction force at 25% deflection). Things to Note when Choosing Marine FendersWhen considering acquiring fenders, several factors should be considered. The fenders’ quality in terms of high energy absorption and low reaction force, as well as a reasonable structure that provides a long life span. The quality of raw materials used, in this case, rubber should also be considered.
High quality products will have a longer shelf life, thus, more cost-effective.Besides the quality of the product itself, the fenders should have an easy set of installation options or the supply company would provide professional installation service. For example in MAX Groups Marine, we either send our installation team to take care of the installation or educate our customers on the procedures and things to note. It is our promise to not only ensure proficiency in the marine fender application, but also add value to vessel owners and dock holders.MATERIALS:The materials used are high grade synthetic rubber qualities EPDM and SBR with extremely highresistance to sea water, oil and other chemical contaminants, ozone, extreme temperatures,ageing, tearing and fatigue. Hardness in general for compounds used for fenders 70? Shore A ±5? The weights mentioned in this brochure are calculated and depends on specific gravity of theused compound.
5 Ways a Rubber Fender System can Fail You. #4 is the Most Overlooked Mistake.A good marine rubber fender system is able to absorb collision energy at an effective and efficient manner during berthing. This helps to prevent vessel and structural damage.
Despite high budgets allocated to develop fender systems, some companies neglect some of the details that may compromise the whole structure. Some of these cases even witness the increase in maintenance costs and accident risks due to poor performing rubber fender systems. The list starts from the most obvious areas a fender system may go wrong, to the slightest details in the structure most often overlooked.A high performing rubber fender system generally has high energy absorption and low reaction force. This relies on the manufacturing quality and the quality of raw materials used.
This is often the top of the list when it comes to marine fender purchasing decisions.2. the importance of the fenders Types There are many different types of popular fenders. Type of fenders used are basically dictated in a project by project basis to optimize performance over the product lifecycle.
Some of the most popular types are arch fenders, cylindrical fenders, supercell fenders, cone fenders and more. Different types of rubber fenders are more suited for different situations and uses. To find out more about the types of fenders5. The Need for Restraint ChainsYou may have noticed that not every rubber fender system requires chains. However, it is important to not forget about them when you really need these chains, for cases like when heavy panels that cannot be comfortably supported by the fender alone. In some cases when chains were needed but not installed, the fender system fails in delivering and was damaged in action.
Chains included should be regularly maintained as well.These are just some of the most overlooked details when it comes to developing an effective marine rubber fender system. Most importantly, be sure to find a trusted supplier for your rubber fender system that assures you their priority. Certification from third party professional bodies is a very important aspect that assures great quality.