Marine Airbags Instruction

Skeleton materials: Nylon "6" Rubber curtainDensity: 90 thread/10cm (width) Fracture strength: 206KN/thread; 294KN/thread2. Airbag entrance: Cast steel, Inner pipe threaded M46*2

Marine airbag for ship launching technology developed on the basis of the traditional launching, use flexible airbag instead of the slide. It overcome many disadvantages of traditional launching: Flexible airbag like an Elastic cushion, It makes the hull free pitching in the process of Ship launching Keep the bottom has a larger contact area, Enable hull's stress is very moderate, So that the paint on the surface and the hull structure will be not damaged.LuHang ship launching airbag is specially designed for launching technology development, Main function is: ship launching and landing, heavy moving. salvage sunken ship, has a very high load capacity, wear resistance, corrosion resistance to seawater.Ship air bag launching technology is invented in the early 1980 s, has a complete independent intellectual property rights of technology in China, after thirty years of improvement and development, has now been ten ton vessels ability in the water. Marine airbag for ship launching technology compared with traditional launching technology, has the following advantages: Save the investment of the basic construction of the shipyard, in the basic construction of shipyard, water facilities, such as the traditional launching way and underwater engineering investment is astonishing. The air bag launching technology of shipyard, only need to build simple ramp, facilities is simple and without complex underwater engineering, save the basic investment of the construction of the shipyard.

Airbag is applied to ship launching more and more widely, launching application method is also improvement.

The process of ship launching airbags application methods are briefly stated below:

1. Calculate and prepare enough rolling airbags, lifting airbags, towing winch, air compressor, etc. We should test the airbags at 1.25 times of its working pressure before using, if exist the leakage phenomenon should be repaired before using.

2. cleaning up the launching way, from berth to ramp, must be flat, remove impurities, pay special attention on the ground about the nails, sharp stones, prevent punctured airbags, ramps should have enough length and depth in the water.

3. make All the ship bottom protruding sharp corners and stern of burrs on the casting be smooth.

4. Use of the traction winch wire rope tie up the ship.

5. Close all sea valves, fixed rudder and propeller

6. Dismantle all blocks, fill in the rolling airbags

(1) smaller ships, airbag bearing capacity can be lifted the ship weight from wood block, can be directly removed block, fill in the rolling airbags.

(2) larger ships, can use lifting airbags at the stern to lift bottom, therefore must first select front pivot and lifting airbags in the best position. like the figure shows that :the more close to the center of gravity the better, if so there are too much blocks before pivot, the work to remove the block is too big. So it should be reasonable position depending on factors such as ship length. try to take Lifting airbag in the end, but it depends on the stern shape, some from the ground is too high or too thin, Lifting airbags lift force is too small, rather than forward appropriately, so each ship is different, must after calculation before selecting the best protection and airbag position, meet the formula:

LO>Q'W*LW

Q-hoisting gasbag lifting force

W-shipping weight

LQ-before hoisting gasbag center to pivot distance

LW - before the center of gravity to pivot distance of the ship

(3) at first dismantle the wooden block at lifting airbag position, and the ones in the front of pivot. Add Lifting airbags, start inflate until the bottom high thar the wood blocko According to the rolling bag put position as plan, dismantle the wooden blocks one by one, dismantle a wooden block then immediately fill in anairbag and inflate. Dismantle all the wooden blocks in turn.

(4) By adjusting the internal pressure, dismantle the rest of the wood blocks with the same method, and inflate. On the safe side, between the airbags, adding the right amount of loose wooden pier at any time, when all the air bag can bear the ship's weight, dismantle the loose wooden piers. In addition, when remove the wooden pier of the same cross section, first remove the middle, then remove the two sides. Workers should be out of the ship when dismantle the last one blocks.

7. Adjust the airbag internal pressure, lift the bottom down to the proper height, ensure that the bottom will not touch the ground in the process of moving ship, small boat also choose 0.2 to 0.3 m generally.

8. All the airbag should be under the ship center respectively, and vertical to thelaunching wayo

9. Start the traction winch slowly released cables, hull begin to move, when the airbag leave the ship bottom, immediately carried to the tail, and fill in airbags according to the calculation.

10. Repeat the above process, and move the boat to the water gradually, when cannot add airbags, make a ban on ship traffic.

11. Dangerous area evacuation, inform the staff on board prepared, when thecondition is appropriate, cut the wire rope, let the ship launch fast If the river isvery narrow, the ship can't launch fast, can use the winch release ropeslowly, letthe boat slowly launch into the water

12 .Larger ships, should install anti-skid device.

13. Recycle airbag

1. Use the winch wire rope tie up hul

2. fill an airbag at the bottom, after inflate, can lift the ship bow to the right height, winch traction to move. Bottom flat type, air bag and the bottom contact area is large, the hull is small, just need one airbag can raise the ship bow. But sometimes, we can't resettle airbag from the front this time we need to put the airbag from one side to another. Some ship head is "V" shape, so the contact area of airbag and ship bottom is small, so the airbag can't lift the ship head, this time the air bag should put at the 1/4 position of ship. Be careful when remove the airbag in case of broke the airbag. If possible, we can dig a "V" groove to increase the contact area. The shipyard can bury airbag at right position when Low tide, pull the ship on them At high tide, then inflate, so the ship can be lifted easily.

3. start the winch, make the ship move slowly, and put the airbags as plan distance, pull the ship to the berth.

4. worked with the jack to lift the ship, build blocks to lift the ship, then pull out the airbags.

When order airbag, need to provide three main parameters:

1.The diameter of the airbag is refer to the outside diameter when the air bag is not compressed and sufficient gas. The Dia have 6 size:0.8m, 1.0m, 1.2m.1.5m, 1.8m, 2.0m. Also accept custom-made (0.8m-4.0m).

2. The using length of the airbag is refer the cylindrical parts length when airbag sufficient gas. It is directly related to the requirement, is one of the main specification of order. the airbag produced by Our company, length is three times of the diameter at least, the biggest length is 24 meters.

3.Rated working pressureCustomer should give the biggest pressure, the rate working pressure is the upper limit of safty work pressure.Whether airbags in compression or not under the compression state, its biggest inflation pressure can't exceed the rated pressure.

Luhang The new integrated Marine high strength gasbag is divided into fivetypes:LH-4,LH-5,LH-6,LH-7,LH-8

1. Distinguished by diameterThe dia selected mainly according to the height of the dolphin. Normally theairbag diameter should be 0.5-0.7m bigger than the dolphin height, otherwise the airbag can't hold up the ship.

Airbags, less than 1.2 mm in diameter, can only be used for little boat launching. ten thousand tons of ship launching need 1.5 m or 1.8 m.when the block height is not more than 0.9m,choose the 1.5m dia airbag. Choose 1.8m airbag when the block height is bigger than 1m.

2. Distinguished by the bearing capacity

3. The bearing capacity

Airbag is flexible,the shape will changed when using. So The bearing area and capacity are changed.

The bearing capacity: F=PS

P= The pressure in the airbag

S=Bottom and airbag contact area

S=0.5 *(D1-D2)

D1: the height when full of gas

D2: the height after compression