Pneumatic Rubber Fenders
Pneumatic rubber fender is fender which is made of synthetic-cord-reinforced rubber sheet with compressed air inside to enable it to float on the water and work as a shock absorber between to ships, or between ships and berthing structures when they come alongside each other on the water. This high pressure floating pneumatic rubber fenders have sometimes been colloquially referred to as “Yokohama fenders” or “Yokohama type fenders”.
What’s the floating pneumatic rubber fenders international standard?
Floating Pneumatic Rubber Fenders
Floating pneumatic rubber fenders was basically manufactured and tested upon international standard “ISO 17357 Ships and marine technology-High-pressure floating pneumatic rubber fenders”. This international standard specifies the material, performance and dimensions of pneumatic rubber fenders, which are intended to be used for the berthing and mooring of a ship to another ship or berthing structure. It also specifies the test and inspection procedures for high-pressure floating pneumatic rubber fenders.
What are pneumatic rubber fenders testing and inspections?
The general inspection tests for a floating yokohama pneumatic rubber fender include material test of rubber, both outer rubber and inner rubber. It should be conducted in accordance with the specifications given in below table and the results shall satisfy the requirements in the table.
And the dimensional inspection. The dimension of all the fenders shall be inspected at the initial internal pressure and the results shall be within the following tolerances:
____ length: +10%, -5%
____ diameter: +10%, -5%
The air-leakage test shall be conducted on all fenders at initial pressure for more than 30 min, and the test results shall confirm that there is no air leakage.
How to proceed floating pneumatic fenders hydrostatic-pressure test?
The hydrostatic-pressure test shall be performed for 10 min at the hydrostatic pressure shown as ”Test pressure at 0% deflection in below tables and there shall be no leakage of water and no defects during the test. The frequency of the test shall be one per 20 fenders of each size and pressure. Circumferential and longitudinal lengths shall be measured at 10 kPa pressure and at the test pressure shown in below table. The temporary elongation shall be as follows.
____ Maximum circumferential temporary elongation: 10%
____ Maximum longitudinal temporary elongation: 10%
Why select pneumatic rubber fenders comparing with marine rubber fenders?
Pneumatic rubber fenders is consisted of natural rubber synthetic tire cord rubber sheets and compressed air which provide nice buffer force comparing with solid marine rubber fenders. It has good buffering performance and can effectively absorb the impact force of ships berthing. Because its interior is air, the compressibility of air allows the fender to disperse energy through deformation when subjected to compression. Its superior energy absorption and reaction force performance to decrease the outer force amid the two ships or ship to quay, softer to prevent the appearance and structure of marines, ships, which is much suitable for sts transfers. Floating Pneumatic Rubber Fenders has high elasticity, can adapt to ships of different shapes and sizes, has a large contact area with ships, can reduce pressure on the surface of ships, and lower the risk of ship damage.The marine rubber fenders are normally applied to ship to quay operations to distribute the collision force and prevent the port structure, it is economical but the reaction force will decrease after sometime.
What are the advantages of pneumatic rubber fenders vs foam filled fenders?
High energy absorption and low reaction force: Pneumatic Rubber fenders absorb more impact energy and have less reaction force at the same size, making them particularly suitable for large/sensitive ships (such as LNG ships) to ship or high dry side berthing; Foam filled fenders also have high energy absorption, but the reaction gradient is more gentle, and the compression of 60% is still stable, which is suitable for frequent berthing and large tidal range environment.
Maintenance and reliability: Floating pneumatic rubber fenders require regular checks of air pressure, and there is a risk of air leakage/explosion, resulting in high maintenance costs; The foam fender is a solid closed hole structure, with no sinking, maintenance free and explosion risk, and its service life is usually 10 – 15 years (about 1 – 5 years for inflatable fenders).
Installation and adaptability: Pneumatic fenders float well with waves, self centering and fitting the hull, suitable for dynamic STS (ship to ship) operations; The foam fenders have buoyancy and are not affected by the tide level. They are suitable for fixed wharves, floating wharves or wind power platforms and other scenes that need stable contact.
Durability and safety: foam filled fenders are puncture resistant, UV resistant, seawater resistant, and still effective when damaged; The outer rubber of the inflatable fender is prone to scratches and loss of cushioning due to internal pressure failure, but some models can be repaired on site.
Cost: Pneumatic fenders are initially expensive to purchase (about 1.5-2 times) and easy to install; The initial cost of foam filled fender is medium, and the long-term TCO is lower (maintenance free+long life).
How to Design and the Selection of Pneumatic Fenders?
The design and selection of floating fenders can be confirmed as per the maximum energy absorption of specific conditions. We should calculate and compare the requirements for the energy of the following condition. The kinetic energy when the ship berthing or after berthing, the energy of relative motion of ship to ship and ship to wharf.
