Pneumatic Fenders: Manufacturing Methods Matter Whitepaper - 28 Pages

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Pneumatic Fenders: Manufacturing Methods Matter Whitepaper

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TRELLEBORG MARINE SYSTEMS Pneumatic Fenders: Manufacturing Methods Matter A Critical Comparison between Conventional Mold Manufacturing and Airbag Manufacturing

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Abstract Pneumatic fenders are extensively used for ship-to-ship transfers at mid seas, double banking operations, and as vessel-to-berth at dock/jetties. Supply of high quality and reliable fenders that can perform effectively even under the harshest environmental conditions, is an absolute necessity. It is therefore extremely crucial for each and every pneumatic fender to comply with the ISO 17357-1:2014 standard that ensures they follow the correct manufacturing process. In recent times, pneumatic fenders that are made by adopting airbag manufacturing process are being supplied for uses...

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THE SAFETY OF PNEUMATIC FENDERS These days, pneumatic fenders are widely used as protection elements from collision between two vessels in the offshore transfer of oil and other chemicals. It’s critical that while this transfer takes place, the highest levels of safety are maintained. When fenders are made up of lower quality materials and are not manufactured to the highest standards, they may fail at critical moments such as during the transfer of crude oil in mid-sea exposed locations. Accidents like these can lead to environmental damage and risk the health and safety of working...

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Ship-to-ship applications STS transfer operations, or lightering, are operations where crude oil or petroleum products are transferred between seagoing tank ships moored alongside each other. Such operations can take place either when one ship is anchored or both are underway at low speeds. Fenders used in STS offshore transfer operations are divided into two categories: Primary fenders: 4 x 3300mmD x 6500mmL* positioned along the parallel body of the ship and provide the maximum possible protection. Secondary fenders: 2 x 1500mmD x 3000mmL* used to protect the bow and stern from accidental...

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In STS operations, a pneumatic fender must do the following: Absorb 5000-6000KJ of energy in rough conditions for some vessels Create low hull pressures during compression Generate enough stand-off between vessels even after high compressions (over 60% of the fender’s diameter) After contact, the discharge ship and the receiving ship usually have different rotational and linear movements. These movements exert huge amounts of shearing forces on the fenders. Therefore, fenders must be able to withstand shear forces even at very high and very low temperatures while maintaining...

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Airbag applications This process is simpler, more economical and arguably safer than other options such as sideways launching. Depending on the size and shape of a ship, the ship may either be launched by the end launching method or by the side launching method. There are three ways to arrange airbags when using the end launching method: Fig 2: Launch of the passenger liner “Empress of Canada” in 1960 using a proper launching facility. The launch is one of the most important events in the entire ship’s construction process and if launches are to occur smoothly, every shipyard needs...

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Ship launching and STS operations In ship launching operations, the high total number of airbags used means that damage to one or two of these is not a serious problem to the operation. In STS operations, where only a few pneumatic fenders are deployed, the situation is very different. The performance and quality of pneumatic fenders is believed to be more critical than in the case of airbags in ship launching. This suggests that the manufacturing process of a pneumatic fender needs distinctive attention to ensure that products are of the highest quality. In launching operations, airbags...

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Comparing airbag and pneumatic fenders The body of a pneumatic fender consists of an inner rubber layer, a reinforcing tire cord layer and an outer rubber layer. These layers are vulcanized (hardened with a high temperature and high pressure sulfur treatment) together which ensure superior bonding between layers of dissimilar characteristics. Outer rubber Cord layers Inner rubber Fig 4: Different components of a pneumatic fender Flange opening

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An airbag consists of three parts: 1. The mouth: a set of metal valves mounted on both ends of the airbags for charging air. One end is often mounted to a lug to pull the airbags under the vessels. 2. he head: A conical part connecting the body T and the mouth of the airbag. Fig 5: Different parts of an airbag 3. he body: The cylindrical part of the airbag T after inflation. Both pneumatic fenders and airbags have components in common that demands certain properties as shown in the following table: COMPONENTS PNEUMATIC FENDERS / AIRBAGS Outer rubber layer The rubber compound of the outer...

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The airbag manufacturing process THE PROCESS CONSISTS OF SEVERAL STEPS: STEP 1 long cylindrical bag is built using a thin layer of rubber and then A vulcanized. This will be used as the inner rubber layer of the final product. After vulcanization, the bag is kept inflated for several hours to check for air leakage. This bag resembles the bladder of a soccer ball. Fig 6: An airbag manufacturing process without a mold. Marine airbag sits on two rollers. STEP 2 long bag, which is the same length as the final product, is placed on top of two rotating rollers and the rubberized tire cords The...

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Fig 7: Trelleborg pneumatic fender

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Comparing manufacturing processes Pneumatic fenders manufactured and supplied by airbag manufacturers adopt the same manufacturing technique as described in the previous section. The manufacturing technique is utterly different from a conventional pneumatic fender manufacturing process using a mold. The following section highlights the difference in the two manufacturing methods: PNEUMATIC FENDERS: THE CONVENTIONAL METHOD Pneumatic fenders are produced inside a mold. The mold sits on two rollers to easily rotate the molds during the building process. Fig 8: Mold for 3.3m x 6.5m length...

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