5 Layers Ship Launching Airbags Docking Natural Rubber Marine Salvage Airbags

Diameter 1800mm Length 16000mm Natural Rubber Ship Launching Airbags

Product Introduction:

Ship launching airbags are also know as marine airbags and ship launching airbags. It's made by synthetic-tire-cord reinforcement layers and natural rubber layers. 

Ship launching airbag is China independent intellectual property rights of innovative products, the products are mainly applied to ship launching and landing, weight lifting, handling, installation of underwater buoyancy aid etc. Nowadays, Ship rubber airbags are widely used in the world. The Products are less limited by space, no large mechanical equipment, can shorten the working period and save the unnecessary cost. Through years of development practice, marine rubber airbag is become more safety, effective and green environmental protection.

Comparing to the traditional slipway docking and launching method, the ship rubber airbags are much environmental, It's low cost and low risk. Unlike most other launching methods that are fixed infrastructures, ship docking airbag has relatively less limitations and can be used in versatile ways. It overcomes the disadvantage of fixed track docking in which capacity of shipbuilding and ship repairing is limited by the fixed infrastructures especially in small and medium-sized shipyards.Ship docking airbag can dock a ship at any seaside. Besides, the ship docking airbags need little maintenance and can be used repeatedly.The ship docking airbags provide support to the hull of the ship, its rolling motion take a vessel out of the water or launch into water. Thus it is obviously more safety than other options like sideways launching.

Specifications: 

Instruction of application in ship launching

Airbag is more and more widely applied in ship launching project. The application method is ceaselessly improved. The airbag application application method for common medium ship launching ship launching is as below,
1. Based on calculation result, enough rolling airbags and lifting airbags, towing machines and air compressors are prepared. Before using, airbags must be inflated and tested without loading(the testing pressure must be no less than 1.25MPa). In case of air leakage, the airbag must be prepared before using.

2. The way for ship movement, including the way from shipbuilding berth to ramp, must be cleaned and flattened. Sundries must be removed from the way, especially sharp iron nails and stones, to avoid piercing the airbag. The ramp should be long enough and wide in water.

3. All the protruding sharp corners and burrs on casting like ”A” bracket and stern post must be polished to be smooth.

4. Fasten the hull with the steel cable of winch.

5. Close the sea chest valves of ship, fix the rudder and propeller.

6. There are many ways to remove all blocks and fill in the rolling airbags. Here we recommend two methods as below. User may choose one basing on the equipment conditions such as ship weight, amount of the airbags, etc.
(A)For light ship, the bearing capacity of the airbag is large enough to lift the ship away form the blocks and therefore blocks can be removed directly and fill in the airbags.
(B)For heavy ship, lifting airbags can be adopted to lift the bottom of stern. Before lifting, firstly specify the optimum position of the front-pivot and lifting airbags. According to the figure as below,

the closer the front pivot to the center of gravity the better, however, it will result in too many blocks around of the front-pivot, which means a lot of workload to remove the blocks manually. Therefore, the position shall be determined reasonably considering such elements as ship length, etc. If possible, the lifting airbags shall be located in the stern. However, the location is also subject to line shape of the stern as the lift of the lifting airbag will not be enough if the bottom is too high to the ground. In this condition, it would be better move forward. Therefore, the optimum position of the front-pivot and lifting airbags shall be decided after specific calculations as the case varies from ship to ship.
Q*Lq＞W*Lw

In the formula,
Q=lift of the lifting airbag
W=weight of ship
Lq= the distance from the lift center of the lifting airbag to the front-pivot
Lw=the distance from the center of gravity of the ship to the front-pivot

7. Firstly, remove all the blocks in the lifting airbags and the ones around the front-pivot. Then fill the lifting airbags and start inflating until the bottom separates slightly from the blocks. Remove blocks one by one from middle to the stern. Whenever blocks of the section are removed, fill in the rolling airbags immediately in the planned position and inflate it appropriately. Followed by continuous block removing until all blocks in the stern are completely removed and the rolling airbags are filled in.

8. Remove blocks from the middle of the ship to the front-pivot and fill in all rolling airbags in the front by modifying pressure of the airbags filled in the stern or similar methods as mentioned above. Of sake of safety, add removed blocks in appropriate number between the filled rolling airbags at any time. The blocks will not be removed until the rolling airbags can support the weight of the ship. Besides, when removed blocks of the same section, it shall be started from middle to both sides. When remove the outermost block, workers shall carry out the work outside the fender.

9. Adjust pressure in the airbags so that the bottom can be lowered to appropriate working height. Make sure that the bottom will not touch the ground while moving the ship. For average small-size ship, the working height could be chosen within the arrange of 0.2m-0.3m.

10. All airbags shall be pointed at the center of the ship and perpendicular to the launching direction.

11. Start the traction winch to release steel cable slowly followed by slow movement of the ship. When the forefront airbags located in the front part separates from the bottom, it shall be placed under the stern immediately and fill in the airbags according to the arrangement space of the airbags defined in the calculations.

12. Repeat the above process to move the ship to waterside slowly. When the airbags can’t be filled in, block the river and forbid any ships to pass.

13. Evacuate personnel in the dangerous zone, Inform staff on the ship to get ready. When conditions such as water depth and so on are enough, cut cable or unhook to shat the ship can launch quickly. If the river is too narrow to realize quick launching, release the cable slowly by traction winch to launch the ship slowly.

14. For large ships, it is necessary to install anti-slip device.

15. Collect the airbags.

Instruction of Airbag Repair

If the airbag is damaged, it can be repaired as long as the rubber doesn’t age seriously(with no crack and stickiness on the surface). And the cords fabric is not loose and rotten. Repair can be made by hot vulcanization or auto-vulcanization. The tolls and repair materials utilized in the former are quite simple. We recommend hot vulcanization, the steps are as below,

1.  Wash the airbags to make sure it is clean both inside and outside and without mud & sand,
oil stain and water logging. Then dry the surface. Note: the immersion time while washing can’t more than 10 minutes.

2.  Mark the repair symbol visibly. Mark the repair area and the mark area is allowed to exceed 15mm, don’t miss the concealed damage.

3.  Prepare the backing
The material of backing is the same as the airbag and the arrangement angle of the cord fabric is consistent with the airbag.
The first layer of the backing is a vertical line. Length=(length of the flaw+50mm)X2
The second layer of the backing is oblique line whose angle is the same as the airbag. It is 20mm larger than the periphery of the first layer.
The third layer of the backing is also oblique line whose angle is opposite to and crosses with the second layer. It is 20mm large than the periphery of the second layer.
The fourth, fifth and sixth layer may be deduced by analog.
The fillet transition with the radius of 40mm-50mm is required for the backing periphery of every layer.
If the wound is a nail hole within 100mm or strip wound in 50-70mm, cross backing shall be prepared. Nylon cross backing is made by bluing two layers of coated Nylon with the crossing of 90°. Its size is 200mmX200mm and others are the same as the backing.

4. Filing the wound
File the wound with steel files or flexible shaft filing machine. The file pattern on the surface should be delicate and even as well as without any rubber scrap, particle. Filing surface depth is about 0.5-1mm. The periphery is 20mm larger than the backing. Breaking and loose is not allowed for filed cord fabric. After filing, blow always the rubber scrap by brush and compressed air.

5. Brush glue and dry
The whole process must be kept clean. Brush thin glue for the first time (glue: gasoline=1:8).There should be no sediment and caking, should be evenly. Forcibly gluing should be performed so that the glue can penetrate into the cord fabric layer in the file slot. The gluing should be uniform and obvious scaffold erecting is not allowed.

6. Viscose
Firstly, brush a layer of base glue with the thickness of 1±0.2mm on the periphery of the wound. Cool down to not gluing hands, paste and press and the glue should not be too tight in case glue failure happens after the new glue contract, then paste the backing. The center of the backing should be targeted at the wound center. The angle of the backing should be in consistent with the airbag line layer. For wound larger than 1M, a layer of coated Nylon fabric should be pasted to the wound, 25mm lager than the wound. Then paste the backing. In the end, one sealing rubber (thickness of 0.8-1mm,wideth in 20mm) should be pasted to the cover the joint of backing edge and body of airbag.

7. Vulcanization
For normal shipbuilding yard, the following simple method can be adopted: set up a frame, ( as shown in the figure) and provide plate, sand bag(fill the inner tube of the abandoned automobile with sand), jack and heated plate(pig iron or steel plate in Dia300mm ,thickness 25mm). The vulcanized airbag to be repaired should be targeted to the center in accordance with the position shown in the figure. First vulcanize the hole and then the wound. If the large wound to be vulcanized exceeds the effective length of the vulcanization, the center should be vulcanized firstly then both sides. The heated plates should overlap 15mm with the previous position in re-vulcanization. The vulcanization shall be finished within 40-50 minutes when the temperature rises to 135±5℃ and pressure is 0.8-0.12MPa.

8. Check whether the repair is bound tightly or not, Flaw such as void, delaminating or sponge and so on are not allowed. As to new glue in heating area, aging, crack, under vulcanization and over vulcanization is not allowed. Inflating test shall be conducted if the repair is qualified.