Marine fenders or rubber fenders are installed as protective equipment to ensure vessels' safe and smooth berthing and reduce or avoid damages to vessels & marine structures in waters and mooring facilities. To use these facilities as a high-quality infrastructure that serves its daily purpose, proper maintenance is essential, primarily to its appurtenances.
Because of constant exposure to harsh conditions, rubber fenders should be maintained and managed in a planned and appropriate manner to sustain their designed service life. To protect assets, including people's safety, optimum performance of marine fenders should be enhanced by avoiding the occurrence of damages and unintended rate of deterioration and ageing.
Maintenance and management should incorporate systems that effectively detects the deterioration of rubber fenders' damage, facilitate technical evaluation, and provide appropriate counter-measures. Basically, it has to contain a comprehensive matrix of the scope, timing, frequency, and methods of checks, diagnoses, and corresponding corrective actions.
Understanding Rubber Fenders by Classification
Assuming that impact is the main deteriorating factors for rubber fenders, it is important to understand the behavior of each kind and classify them according to how they absorb energy from berthing vessels.
V-type rubber fender- also known as arch fender. The fender body is the resisting mechanism itself and absorbs the berthing energy of the vessel by buckling and deformation of its body. Therefore, it is straight forward to pay attention to signs of deterioration at the rubber body due to external force.
Rubber fender with panels – similar types are cell fender and cone fender. A steel panel with resin pads such as UHMW PE, mounted at the rubber fender body, initiates the contact from berthing vessels and transfer the impact to the rubber fender which absorbs the energy by buckling deformation. Since the vessel does not come in direct contact with the rubber, the damage and breakage of the rubber body is minimal, care must be taken for the corrosion and deformation of the steel fender panel.
Pneumatic fender – absorbs the energy of the berthing vessel by its highly elastic features due to the compressed air pumped into the body - fabric-reinforced rubber bag. Floating air fender is generally protected by a net, so damage and breakage of the rubber main body is slight, deterioration of the net is more susceptible. Fixed air fender with a fender panel behaves similarly to a rubber fender with panel, and attention must be paid to the corrosion and deformation of the steel.
For both floating and fixed type, it is necessary to maintain the air pressure for maximum efficiency.
Cylindrical rubber fender – also similar to D-type and square type. Vessels come in direct contact with the rubber body and absorbs berthing energy by deformation of the rubber, it is necessary to pay particular attention to deterioration by external force.
Most Common Forms of Marine Fender Deterioration
Rubber marine fenders has different deterioration modes depending on the type as follows.
Rubber body: Drops, tears, permanent deformation, missing rubber, cracks, chipping, separation, wear, ozone cracks, cuts, burns, bolt hole damage
Accessories (fixings): loose, bent, missing, cut, corrosion
Rubber body: tears, permanent deformation, cracks, separation, ozone cracks, burns, bolt hole damage,
Panel: deformation, corrosion,
Fixing: loose, bent, missing, cut, corrosion
Support: bent, cut, corrosion
Resin pad: wear, abrasion, cut, missing, burn
Rubber body: cracks, chipping, separation, wear, ozone cracks, tears, burns, bolt hole damage
Air inlet valve: damage, corrosion
Body attachment: malfunction, corrosion
Net: corrosion, cuts, cracking, wear, burns
Mooring attachment: fender panel, support and resin pad: corrosion, etc.
Rubber body: drops, cracks, missing rubber, tears, chipping, wear, ozone cracks, burns
Supports: bent, cut, corrosion
Inspection and Diagnosis
Detection and monitoring of damages and deterioration among rubber fenders at work is equally necessary to the design and material selection phase. This is to ensure that these port & harbor utilities are performing as designed for a long period of time and unfavorable circumstances due to failure are avoided. Frequency of mandatory inspection are the following.
Initial check – upon installation, assessment of the condition of the rubber fenders as unit and as a system should be carried out. Individual checks followed by commissioning through trial berthing can be the most ideal sequence of the test.
Daily check - routine inspection to assess the deterioration of the marine fenders on daily basis. The top priority of daily check is to detect any type and extent of damage and occurring deterioration.
Periodic check - periodic checks and diagnoses are conducted regularly to determine the progress of deterioration among rubber fenders. Periodic checks and diagnoses should be carried out systematically and continuously based on a pre-engineered inspection plan to evaluate the effectiveness of corrective measures in used and to be able to plan ahead in case of possible major troubleshooting.
Occasional check - occasional checks and diagnoses are conducted to confirm the damage of fenders when deterioration is recognized and in the events of unusual port incidents such as fire, uncontrolled berthing, and excessive vessel motion caused by wind storm, earthquake, tsunami, etc.
Counter-measures
All kinds of rubber fenders eventually suffer deterioration over a period of time due to ageing and the accumulation of impacts they have sustained. Preventive measures against deterioration must be taken about once or twice during the service period of a facility. Maintaining the working quality of rubber fenders is critical because a decrease in the number and function of rubber fenders can cause suspension of mooring operations resulting to losses.
With regard to the rubber body, it is common to most types to carry out replacement as a post-measure because preventive measures are difficult or not economical. However, in the case of pneumatic fenders, checking air pressure, repair, and reinforcement of the rubber body are practical maintenance measures.
In addition to unit replacement, measures for rubber fenders may include repair, repositioning, or restriction of use if possible. Appropriate measures can be taken from various viewpoints, such as deterioration status of rubber fenders, importance of facilities, and economic efficiency.
Action | Description of Corrective Action |
Removal | This happens when fender is no longer needed |
Replacement | This is done when preventive maintenance measures such as repair is difficult or not economical. Wise scheduling of replacement operation must be observed if suspension of port operations is not possible |
Repair | This is advised when the performance and durability of the fender can be restored to a certain acceptable level. Generally, it is difficult to recover the function of a rubber body by repair or reinforcement, but for pneumatic fenders, repair or reinforcement is highly recommended provided that technical knowledge is present |
Re-positioning | Switch the positions of frequently used rubber fenders with less frequently used rubber fenders. If practical, fenders can also be shuffled in a manner that intact or strong parts of the fenders are oriented to absorb greater impacts. However, for partial failure, adjusting fenders’ position may be possible but it is necessary to consider possible safety consequences |
Service Restriction | Modification of conditions such as positioning of vessels in the dock, berthing speed and angle to moderate the severity of impacts, etc. These solutions require technical knowledge and proper consultation to all concerned. This can be used as an emergency or temporary solution depending on the circumstances at hand |
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ESC has strategic partnerships with PIANC registered manufacturers with over 20 years of experience delivering marine fender system solution worldwide.
Our marine rubber fenders has varieties in over 50 profiles, 5 rubber grades, and types such as the Cone Fender, Cell Fender, Element Fender, Arch Fender, Cylindrical Fender, Square Fender, Pneumatic Fender, and Foam Filled Fender.
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