HDG Ship Rubber Airbag Good Bearing Inflatable Boat Launching Anti Explosion

Shipyard Using Good Bearing Capacity Ship Rubber Airbag

History Of Ship Rubber Airbags

6000 years ago, our ancestor begin to use log-rolling method to lift and move weights, which is still widely used in daily production and actual life nowadays. Marine rubber airbag is designed with soft rubber to lift and carry weights, based on log-rolling method.

Boat Launching airbag is an innovative product of Chinese own proprietary intellectual property rights. It has wide application like ship launching & upgrading, caisson lifting & moving, heavy weights lifting, underwater-engineering buoyancy aid. The marine rubber airbag is not limited to space and heavy machinery, which could efficiently shorten the construction period and save lots of funds.

Feature of Shunhang Products:

1. Big carrying capacity

The carrying capacity of the inflating marine rubber airbag is an important indicator of its quality. The CB/T 37951996, The Airbag For The Ships Up To Slipway And Launching, specifies its working pressure and the load-bearing capacities per meter under various compression ratio. Our new generation of airbags are made of novel rubber compounding and high-tension fortifying fiber. Their carrying capacities have been over one times stronger than the standard requirements. That means that less airbags are needed for the ships up to the slipway and launching if with Shun hang marine rubber airbags meanwhile the safe reliability is also guaranteed.
 

2. High capacity against compression and twisting

When the airbag moves under the ship bottom, it will be compressed between the ship bottom and the ground. As the rolling velocities are not the same among them, they would be torsional deformed. This composite deformation created by both the compression and twisting is described as compressed and twisted movement. When such compression and twisting happens on the air bag, its partial wall would buckle. Then the wall in structure of the multi-layer fortifying fibers would very easily laminate and tear out, resulting the breaking of the fortifying fiber and consequentially the bursting of the entire airbag.

3. New design of anti-bursting construction at the end

For our new generation of airbags, both the rubber compounding and making process are improved so that their structural tearing strengths are improved and so for their capacity for twisting and compression resistance. The deflating possibility would increase at the joint of the end ironwork and the rubber as the working pressure rises.Once it leaks at the end after repeated operation, the end would be more likely to burst out under the high pressure and injure the people.Such accidents due to poor air bag quality have happened many times in the ship launching. We should keep alert on it. To meet the requirement on the air tightness under high internal pressure, the new anti-blasting construction is designed with the end to enhance the binding strength and air tightness at the joint of the bag body and end ironwork. This design could meet the increased working pressure and has been free of the leakage so far in use and proved safe.

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.

Attention During Application

1. Working pressure must be controlled strictly, it is not allowed to exceed the working pressure.
2. No sharp and protruding hard object on the contacting surface of the airbags, to avoid the puncture on the skin of airbags.
3. Avoid the distortion along the length of airbag.
4. Empty inflating test must be performed if the airbags were not used for a long time or after reparation. The pressure should be as same as the testing pressure of our company. Inspectors must be at least 3 meters away from the airbags. For repaired airbag which was damaged in large scale, its working pressure should be lowered reasonably. Besides, annual check should be conducted on airbags which are used frequently.
5. Don’t drag the airbags on the ground.

Our Ship Rubber Airbags