Comparison of marine airbag and SPMT for heavy load out

Marine airbags are often called ship launching airbags that indicates they are most used for launching ship into water. Inspired by ship launching, people developed many applications of marine airbags in different fields, the most remarkable one is heavy lifting and moving with marine airbags.
SPMT stands for self-propelled modular transporter, a platform vehicle with a large array of wheels; it is equipped with Power Pack Unit which provides the propulsion.
Obviously marine airbags are not as famous as SPMTs in heavy lifting and transport fields. The main reason is that marine airbag is not a high developed industry product yet; its ISO standard was issued only at 2011 years. Due to special manufacture technology marine airbags can only be made in China which also limited its worldwide development.
Marine airbags heavy lifting and load out has similarity with SPMTs but more difference. A comparison may help people to know their individual characters.

Heavy Lifting

Lifting Capacity
The SPMTs consist of four-axle units or six-axle units, the maximum allowable axleline payload is 30 tons per line. Then we can know:



Marine airbag’s lifting performance is decided by its working height and inner pressure.

Airbag specification Load Lifting height Airbag pressure
1.0 ×15 m 471 tons 0.5 m 4 bar
1.5 ×15 m 235 tons 1.0 m 2 bar
2.0 ×15 m 420 tons 1.0 m 1.8 bar

Provided there is a caisson with follow dimension needs to be lifted.

Length（m） Width（m） Height（m） Weight（t）
20.45 13.45 17.3 2357

To lift this caisson at 0.5 m high from ground people may choose 6 pieces airbags (1.0×15 m). The total 6 pieces airbags’ lifting capacity is 422×6=2533 tons. Air bags can be positioned with 4 m space.
To lift this caisson with SPMTs, people will need 2357/180=13 units 6 line modules but the structure dimension decides maximum 12 units modules can be deployed. Then SPMTs is not suit for this caisson lifting and moving.

Article from : Marine airbags VS. SPMTs

Eversafe project of concrete structure shift with air bags

Tieshan Port Industrial Park is located in Guangxi Zhuang Autonomous Region, China. The Park is one of the three important industrial zones for the Beibu Gulf Development, which was approved by China’s Central Government.
The construction project consisted of two phases: the NO.1-2 berth construction have already been finished and NO.3-4 berths construction work started from August 2010.
In plan total 40 Caissons will be installed for NO.3-4 berths construction. Eversafe Marine was engaged by the Administration for the Beibu Gulf to carry out caisson transportation works, from fabrication site to submersible barge with heavy lifting marine airbags. Caisson transportation with marine air bags is a new technology which doesn’t need rails and trolleys and can transport concrete structure on compacted ground. So it enables fabricating caissons on temporary site which can be located near shipping position. Using balloons to transport caissons to submersible barge then launch it can save more than 40 percent investment comparing with trolley transportation method,not mention the time saving.
The first caisson measures 24 meters by length, 16.4 meters by width and 20.75 meters by height. Its weight reaches 3050 tons. To move caissons from construction site to shipping out position , Eversafe team made the masterly plan which consists of three steps: lifting first ,length ways move then transverse move. Total four winches were employed to control caisson movement: two winches from submersible barge to pull caisson move forward and other two winches were used to stop caisson.
Total 8 pieces heavy lifting air bags with 1 m diameter and 16 meters length were used to lift the caisson. Each air bag carry about 380 tons with 0.25 Mpa pressure. To roll caisson out 24 pieces 8 meters long air bags were arranged in two rows and kept in 40 cm height to ensure caisson movement stability. It took us about 3 hours to transport the first caisson to ship out position.
When using air bags to move caissons aboard submersible barge, the barge need not to sit on seabed. Often people use steel plates to connect bank and barge deck to roll caisson on to board. Submersible barge can rise or sink by adjusting ballast water to adopt coming caisson. And in flood tide the barge operation will be easier.

LPG Cargo Tank Air bags lifting Project-Eversafe Marine

On May 29 2011 Eversafe Marine Engineering Company successfully completed a LPG Cargo Tank lifting Project with heavy lifting airbags in COSCO shipyard. That VLGC cargo tank weighs 1600 tons with 40 m length , 30 m width and 20 m height.
During the Japanese Tsunami in March 2011 that VLGC hold space was damaged and water ingress of approximately 7m above the inner bottom caused the cargo tank to float freely. As a consequence the 64 pieces wooden liners from the lower tank supports have floated out and the tank was sitting directly on the steel plates. The cargo tank had to be lifted in order to fit back the wooden liners.
Airbag lifting would take and distribute the load evenly over the inner bottom and tank bottom. Contrary to hydraulic jacks and floating crane no additional reinforcements of the structure was necessary.
Also airbag lifting can be precisely controlled which is also one of selection reasons. The tank in hold place has very limited space from the top and sides: the space on top of tank is limited to 12 cm and in four sides only 60 cm space is available. To put back wooden liners tank need to be lifted up11 cm from the support blocks and lowered down one centimeter by one centimeter. So the lifting and descent must be totally controlled.
A pre-inspection was carried out by Eversafe Marine in order to determine the space available for the airbags. One access hole was cut in the portside of the hold space to allow smooth transport of airbags.
To settle airbags in proper positions the limited space made troubles for us. Since no heavy instruments can be installed for the airbag hauling in the hold space people have to use chain blocks as main transportation tool. The height from hold space to tank bottom is 64 cm people even can not squat when they work under the tank. It is a hard work to settle total airbags in their positions in two days.
In the morning of May 29 2011 the airbag tank lifting work started. Eversafe technicians carefully controlled the inflation process to ensure upright lifting up. In our hour the tank was lifted 11 cm up from the support blocks. In the afternoon when all wooden liners were placed in proper positions the tank was lowered down one centimeter by one centimeter until liners fit into frames. Tank lifting/lowering was completed on 29 May, 17:00 local time. All 64 pieces of wooden liners were placed back successfully.