Marine airbags will cause people most interest once people have the experience of watching marine airbag ship launching. It looks like the magic show that big vessel run into water by riding rolling pneumatic rollers. In China most new built vessels whose DWT below 60,000 are launched with the “flexible ship launching technology” which definitely differ from traditional launch methods. Marine airbag ship launching technology gets the least limitation of landscape so it can save people most money and time.
The first difficulty for people to apply marine airbag for ship launching is how to decide if the vessel can be launched by airbags and select marine airbags. Most Chinese manufacturers will only tell you to do what but not why to do that when you consult with them for your launch project. In fact some manufacturers don’t know much of the marine airbag ship launching technology even they make marine airbags. Some real jokes: a manufacturer sold many marine airbags to a Turkish client and when people prepared launch they found no place to fit all marine airbags into bottom of vessel. Another joke sounds like that a manufactures sold 20 pieces marine airbags with 2.5 meters diameter to Malaysian shipyard to launch a 60 meters tugboat with only 700 tons. To avoid be fooled by some unprincipled manufacturers, there are some lies that people must know.
Lie One: Bigger diameter means better performance
People may be fooled by numeral tricks when they read performance data of marine airbags issued from manufacturers. People are leaded to believe that the bigger diameters of marine airbags have the better performance. In fact the performance of marine airbags is decided by the burst pressure which means the maximum pressure of airbags can bear. It is easy to understand that for the same material made bigger volume container will has less burst pressure. From the test data people can prove this prediction comes from common sense: the bursting pressure of marine airbags with 1.5 and 2.5 meters diameter is 0.67 Mpa and 0.23 Mpa respectively. When a 1.5 m diameter marine airbags and another 2.5 m diameter one are inflated to the same pressure, it is definitely the bigger diameter one will rise up heavier objects because of its bigger contact surface. But the bigger diameter one gets some problems that its pressure can not exceeds 0.23 Mpa and it will lift up vessel higher which will cause the extra demand of launch water level also its bigger contact surface with ground will need more slip force for vessel to start movement. In a word, marine airbags with the diameters exceed 2 meter are suit for some special lifting use not for vessel launching. During ship launching process marine airbags will be compressed and their inner pressure will rise to be nearly 2-3 times of initial pressure so marine airbags must have 3 time safety coefficient. Most 2-2.5 meters marine airbags can not get 2 times safety coefficient.
Lie Two: More plies means better safety
Some clients would like to believe marine airbags with more plies will ensure better safety. It is true that the 7 pliers marine airbags’ maximum pressure is higher than 6 pliers one. But good arrangement and maintenance will ensure much more safety of your marine airbags. The thickness and maximum pressure will increase no more than 8% when marine airbag’s plies increase one. So in most cases marine airbags with more plies can not offer a visible enhanced safety but the psychological effect. In fact the professional manufacturer has optimized the plies and structure of marine airbags. Most popular Evergreen marine airbags are 6 pliers. They have the best cost performance and more than 5 times safety coefficient which is enough for most marine projects.
Lie Three: More marine airbags employed for project means better safety
Like people always say going too far is as bad as not going far enough, too many marine airbags for the launch project may cause danger. There is a minimum space required for marine airbags arrangement. If marine airbags are placed too closer, they may huddle together and can not roll forward when they are compressed more during the launching process. Please note marine airbags will be compressed differently in the different launching period. Even marine airbags are not adjoining before the launch they can still huddle together in launching period.
After see through lies of marine airbags people may ask then how can we know if our vessel can be launched by marine airbags? The answer is simple: four conditions should be satisfied.
1. Vessel is prepared to be end launching
2. DWT below 60,000 tonnes
3. Launching channel’s width no less than 1.5 times of vessel’s length
4. For some special ship launching such as V-shape vessel additional brackets may be needed
To select suitable marine airbags for your marine projects you may refer the following.
There are two industrial standards for marine airbags in China.: one is product standard named “Air bag for ship up to or down to launching way “(CB/T 3795-1996 / CB/T 3795-2009); another is technology standard named “Technological Requirements for ship Upgrading or Launching Relying on Air-bags” (CB/T 3837-1998).The latter offer the basic calculation of marine airbags employed in a marine project.
According to Chinese industrial standards people will know the approximate quantity and specifications of marine airbags needed for their projects. There maybe optional specifications to be selected for a specific marine project and a good manufacturer should know the best choice. Suggestions from Qingdao Evergreen Maritime Company: for ship launching, the airbag’s diameter and length should not exceed 2.0 meter and 18 meter respectively; for caisson conveying, the 1.0 meter diameter is suitable for most projects.
The data of marine airbags’ blasting pressure will reveal the product’s quality level. For top quality marine airbags, such as one 1.5 m diameter and 7 m length Evergreen marine airbag, the blasting pressure is 0.67 Mpa which indicates the safe coefficient is more than 5 considering its 0.12Mpa working pressure. Never forget to ask for the maximum pressure from manufacturers if you want to buy marine airbags from them.
Full technical service is the qualification of a good company. Although general calculation formula or performance data of marine airbag can be got from most factories but detailed calculations based on mathematic model and experience is more important to the success of marine projects.
In a word marine airbags is a good powerful tool for lots of marine projects but people need to know some principles before using it.
The first difficulty for people to apply marine airbag for ship launching is how to decide if the vessel can be launched by airbags and select marine airbags. Most Chinese manufacturers will only tell you to do what but not why to do that when you consult with them for your launch project. In fact some manufacturers don’t know much of the marine airbag ship launching technology even they make marine airbags. Some real jokes: a manufacturer sold many marine airbags to a Turkish client and when people prepared launch they found no place to fit all marine airbags into bottom of vessel. Another joke sounds like that a manufactures sold 20 pieces marine airbags with 2.5 meters diameter to Malaysian shipyard to launch a 60 meters tugboat with only 700 tons. To avoid be fooled by some unprincipled manufacturers, there are some lies that people must know.
Lie One: Bigger diameter means better performance
People may be fooled by numeral tricks when they read performance data of marine airbags issued from manufacturers. People are leaded to believe that the bigger diameters of marine airbags have the better performance. In fact the performance of marine airbags is decided by the burst pressure which means the maximum pressure of airbags can bear. It is easy to understand that for the same material made bigger volume container will has less burst pressure. From the test data people can prove this prediction comes from common sense: the bursting pressure of marine airbags with 1.5 and 2.5 meters diameter is 0.67 Mpa and 0.23 Mpa respectively. When a 1.5 m diameter marine airbags and another 2.5 m diameter one are inflated to the same pressure, it is definitely the bigger diameter one will rise up heavier objects because of its bigger contact surface. But the bigger diameter one gets some problems that its pressure can not exceeds 0.23 Mpa and it will lift up vessel higher which will cause the extra demand of launch water level also its bigger contact surface with ground will need more slip force for vessel to start movement. In a word, marine airbags with the diameters exceed 2 meter are suit for some special lifting use not for vessel launching. During ship launching process marine airbags will be compressed and their inner pressure will rise to be nearly 2-3 times of initial pressure so marine airbags must have 3 time safety coefficient. Most 2-2.5 meters marine airbags can not get 2 times safety coefficient.
Lie Two: More plies means better safety
Some clients would like to believe marine airbags with more plies will ensure better safety. It is true that the 7 pliers marine airbags’ maximum pressure is higher than 6 pliers one. But good arrangement and maintenance will ensure much more safety of your marine airbags. The thickness and maximum pressure will increase no more than 8% when marine airbag’s plies increase one. So in most cases marine airbags with more plies can not offer a visible enhanced safety but the psychological effect. In fact the professional manufacturer has optimized the plies and structure of marine airbags. Most popular Evergreen marine airbags are 6 pliers. They have the best cost performance and more than 5 times safety coefficient which is enough for most marine projects.
Lie Three: More marine airbags employed for project means better safety
Like people always say going too far is as bad as not going far enough, too many marine airbags for the launch project may cause danger. There is a minimum space required for marine airbags arrangement. If marine airbags are placed too closer, they may huddle together and can not roll forward when they are compressed more during the launching process. Please note marine airbags will be compressed differently in the different launching period. Even marine airbags are not adjoining before the launch they can still huddle together in launching period.
After see through lies of marine airbags people may ask then how can we know if our vessel can be launched by marine airbags? The answer is simple: four conditions should be satisfied.
1. Vessel is prepared to be end launching
2. DWT below 60,000 tonnes
3. Launching channel’s width no less than 1.5 times of vessel’s length
4. For some special ship launching such as V-shape vessel additional brackets may be needed
To select suitable marine airbags for your marine projects you may refer the following.
There are two industrial standards for marine airbags in China.: one is product standard named “Air bag for ship up to or down to launching way “(CB/T 3795-1996 / CB/T 3795-2009); another is technology standard named “Technological Requirements for ship Upgrading or Launching Relying on Air-bags” (CB/T 3837-1998).The latter offer the basic calculation of marine airbags employed in a marine project.
According to Chinese industrial standards people will know the approximate quantity and specifications of marine airbags needed for their projects. There maybe optional specifications to be selected for a specific marine project and a good manufacturer should know the best choice. Suggestions from Qingdao Evergreen Maritime Company: for ship launching, the airbag’s diameter and length should not exceed 2.0 meter and 18 meter respectively; for caisson conveying, the 1.0 meter diameter is suitable for most projects.
The data of marine airbags’ blasting pressure will reveal the product’s quality level. For top quality marine airbags, such as one 1.5 m diameter and 7 m length Evergreen marine airbag, the blasting pressure is 0.67 Mpa which indicates the safe coefficient is more than 5 considering its 0.12Mpa working pressure. Never forget to ask for the maximum pressure from manufacturers if you want to buy marine airbags from them.
Full technical service is the qualification of a good company. Although general calculation formula or performance data of marine airbag can be got from most factories but detailed calculations based on mathematic model and experience is more important to the success of marine projects.
In a word marine airbags is a good powerful tool for lots of marine projects but people need to know some principles before using it.
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