Mechanized underwater welding and cutting for VLFS

Mechanized underwater welding and cutting techniques are very important for actual usage of very large floating structures (VLFS). On-site welding plays a major part in the construction process. The total weld line is very long and a half part is submerged under water. The water curtain type wet underwater welding technique had shown its excellent ability for the construction of a Mega-Float which was carried out by the Technological Research Association (TRA) of Mega-Float. A mechanized underwater welding machine in overhead position was also developed for maintenance of the Mega-Float. Public facilities like an offshore airport require frequent maintenance and alteration to keep up with the latest needs and safety. The underwater mechanized cutting technique is a suitable method for alteration and dismantling. In the case of alteration, the quality and operating cost of cutting are very important. That is the reason why mechanized underwater flame cutting is required. A high quality cut was obtained under severe conditions such as heavy attachment of bio-fouling on the bottom.