ClassNK Approves Fillet Welding Consumable

Classification society ClassNK announced that it has granted type approval for the new MX-200F welding consumable, developed by Kobe Steel Co., Ltd. (KOBELCO) to improve welding efficiency and coating quality in commercial vessels.

Until now, shipbuilders using conventional fillet welding consumables had to make two welding passes for the required weld leg lengths of around 8mm or above. As the IACS Common Structural Rules (CSR) require the use of 8mm leg lengths in some structural members, this has meant that the relevant welding time for oil tanker and bulk carrier newbuildings has virtually doubled. The IMO Performance Standard for Protective Coatings (PSPC), applicable to vessels over 500 gross tons and double-sided skin spaces in bulk carriers over 150m in length, also substantively requires welding beads to have a smooth profile in order to ensure the required paint film thickness, further increasing the difficulty of welding work.

To help address these challenges and improve welding efficiency, Kobe Steel, Ltd., Shin Kurushima Dockyard Co., Ltd. and ClassNK began a joint R&D project to investigate the relationship between the profile of welding beads and paint film thickness. The research, which was carried out as part of ClassNK’s Joint R&D for Industry program, resulted in the development of KOBELCO’s new MX-200F fillet welding consumable. MX-200F not only allows one pass welding with the leg lengths of around 8mm, but also ensures welding beads have a smooth profile in line with PSPC requirements. The application of this welding consumable is expected to greatly reduce man-hours required for this kind of welding work compared to existing consumables.

Upon completion of the development process, KOBELCO submitted the new welding consumable to ClassNK for approval for application in vessel construction. After a thorough testing and review process, ClassNK determined that MX-200F met the requirements of the ClassNK Rules and approved its use in ship construction.

The development and approval of MX-200F represents the latest success of ClassNK’s Joint R&D for Industry program which has provided funding and research support for nearly 300 joint maritime R&D projects since its founding in 2009.

classnk.or.jp