ClassNK Guidelines, Friction Stir Welding on Hull Structures

Tokyo based classification society ClassNK has released the guidelines on the application of friction stir welding to the construction of commercial maritime vessels. The new Guidelines on Friction Stir Welding lay out clear requirements for the use of this advanced welding process for commercial shipbuilding, and are the first such guidelines to specify approval procedures for the use of friction stir welding on hull structural members.

Currently, the majority of the world’s merchant vessels are constructed using semi-automatic CO2 welding and submerged arc welding. However, in recent years a number of new high performance welding processes have been developed with the aim of improving both the quality of welded joints and the efficiency of the welding process. Many of these new processes are already being used in the automotive and aerospace industries, and their introduction to the maritime industry has been highly anticipated.

One such new process that has already found use in the maritime industry is friction stir welding. Friction stir welding is a solid-state welding process that allows materials to be joined without thermal deformation, thus avoiding many of the potential defects associated with traditional fusion welding procedures. While friction stir welding has already been used in the welding of aluminum structures for ferries and military vessels, the lack of clear guidelines for the use of this new process on the hull structures of commercial vessels has been one of the factors limiting its widespread use in the greater shipbuilding industry.

Friction stir welding is a technology that feel could have tremendous benefits for the shipbuilding industry, but the lack of clear standards for its application in commercial shipbuilding has been a major obstacle preventing its widespread use. ClassNK’s goal in developing these new guidelines was to make the use of this new welding process a practical reality for the shipbuilding industry, and thereby contribute to the building of safer and more robust vessels.

The new ClassNK Guidelines on Friction Stir Welding were created to be a unified reference for the approval of welding procedures for friction stir welding, including the use of friction stir welding on hull structural members. The guidelines not only make clear the numerous technical requirements that apply specifically to friction stir welding, but also conform with the ClassNK Rules for the Survey and Construction of Steel Ships, and so are expected to be a valuable tool for shipbuilders in the construction of newbuildings.

The new guidelines are available on the ClassNK website at the following address:
http://www.classnk.or.jp/hp/Rules_Guidance/Guidelines/fsw_e.pdf