Marine Airbags for ship upgrading and launching

1 Air bag(AB)

The main supporting elements of the slip are air bag ( hereinafter - AB) . Ship transferring from the building area to the slip is produced approaching the deflated air bag under the vessel and inflating with compressed air. The launching is made on the air bags used as the rollers. This launch can be both uncontrolled and controlled. In the latter case the launching speed is regulated by the traction mechanism which is located at the head of the slip.

The distance between the air bags depends on the light-ship, the length and width, but not more than 6 m from the bag centers. To install the bag the space at least 25 cm in height and width at least the half of the circumference of the air bag is required. 

Air bag (hereinafter - AB) for upgrading and launching of vessels and dragging heavy dimensional structures with flat basis (without protrusions). Also suitable for use as a pneumatic jack. Pneumatic bags are intended for ship transportation, repair and painting.

2 The main technical parameters of pneumatic bags

3 Technical description of the AB The pneumatic bag AB consists of a rubber-cord shell with tapered ends.

Pneumatic bag has two threaded bushings on the tapered ends, one of them is connected to the pressure control unit and the valve for the compressed air, another end is equipped with eyebolt  to drag the bag during the operation. At customer’s option AB can be supplied with two pressure control units (Fig. 1).

Picture 1 - Layout of a the pneumatic bag AB-1,2-10-1,6.

 AB may be operated at the temperature range from -10 ° to + 60 ° C, with the media: river and sea water, industrial water, weak acid and alkaline solutions. The outer rubber layer protects the bags from abrasion and other external influences. This layer has high disruptive strength, withstand a load in harsh operation environments.

The rubber compounds and rubber-coated cords for bags are made in our own preparatory workshop of the high quality raw materials. Control of raw materials and  rubber compositions is carried out in the laboratory of the enterprise. The formulation of rubber compounds is constantly being improved. This allows to improve the wear resistance and abrasion of the rubber, its performance characteristics, to make it suitable for each customer individual need. Because of the peculiarity of AB-manufacturing technology the  incomplete airbag  airtightness is allowed.

Pneumatic bags can be used both by large and small shipping and ship repair facilities, oil and gas, nuclear power, aerospace, railway industry enterprises, bridge-building organization, road building companies, rescue officers.  In practice, a bags with a diameter of 0.8 ... 2.0 m, effective length 6 ... 18 m and a total length of 7 ... 21 m, with an operating pressure of 0.07 MPa ... 0.24 are used. Airbag dimensions and specifications can be changed at the request of the consumer.

4 Basic rules of the bag operation  

Handling, transportation and installation. 4.1 Airbag loading and unloading is to be made one by one on pallet folded, without using of transport rope hooks or any metal objects that can damage the product. 4.2 It is not allowed to drag bags on a hard surface because of the risk of damage.

4.3 After each use, the outer surface of the bags must be cleaned, the air must be removed and the bags must be folded in places of inflection. The transportation of bags must be carried out on a flat horizontal platform, by road or by rail. 4.4 The long distance transportation of the inflated bags is not permitted. The  rolling of the inflated bags on the territory of the enterprise is allowed, if there are no objects on the ground (like broken glass, nails, some other sharp objects) that may damage the shell structure of the bag.

4.5 The installation  of bags is carried out by the specialists briefed on the use of bags. 4.6 When you connect bags to pneumatic system (receivers, compressor), check the correct operation of the gauge, when the air pressure in the bags must be checked by two pressure gauges, if the pressure gauge readings will be different, it is necessary to stop pumping and replace faulty gauges.

5 Slip and bags preparation 

5.1 Surface of the launching track (slip) must slope towards the water and go into the water at a certain depth. The slope of tracks depends on the launching weight of the vessel. The slope is determined by ratio of the height of full raise to the length of the slip. The value of the slope for a variety of slips depends on the size of vessels to be launched:

the slope for small vessels is from 1 : 8 to 1:12

the slope for middle vessels is from 1 : 14 to 1:16

the slope for big vessels is from 1 : 18 to 1:24 

Before the operation it is necessary to clean the slip surface removing foreign objects (like metal, broken glass, nails and some other sharp objects) that may damage the bag shell structure and to level the surface with sand (removing the pits and hills). 

5.2 During the operation is not allowed:

• exceedance of the working pressure in the bag shell;

• lifting of loads which  exceed the weight carrying capacity bags;

• moving or dragging bags on surfaces, which can damage the bag;

• rolling bags when the lifting height is less than 400 mm;

• storing bags inflated for a long time.

5.3 When using the bags the perpendicularity of the axis of the vessel to the axis of the bag must be strictly observed.  

5.4 The physical impact on the outer surface of the bag is prohibited because of the risk of the destruction of the layers and the break.

5.5 By launching, upgrading and transporting of the vessels the parallelism and at most 6 meters intervals between the airbag axes is to be adhered, if the operations are carried out without the development of special methods of launching, upgrading and transporting of the vessels.

5.6 When transporting the vessel on bags the bags should be placed in strict compliance with the schemes specified in the project documentation.

5.7 Use of rubber pneumatic bags for other purposes is prohibited.

5.8 Deflated pneumatic bags are slid under the ship and inflated with compressed air, carrying out the transfer of the vessel from the construction area to the launching device. The launching is made on the air bags used as the rollers. This launch can be both uncontrolled and controlled. In the latter case the launching speed is regulated by the traction mechanism which is located at the head of the slip.

Any questions, pls feel free to contact me----Jason Zhang

skype :zxb188 mail: jason at florescence.cc

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