Fitness-for-service design for underwater wet welds

This paper presents a new concept of improving the use of wet welds for underwater structure repair or construction. A flexible intermediate connection pad, prefabricated on land and welded to the structural members in wet conditions, cushions the stresses on joints. The inherently inferior impact property of the wet weldment can be coped with proper design of this cushion pad. The wet welded joint can therefore fit its designed purpose. In this study, both design analysis and experimental tests were conducted to demonstrate the design solution using the cushion pad. A statistical data base on wet weld properties was first developed to define the performance level of wet welds. The fitness for service of the flexible connection was evaluated by impact testing. The results show that the performance level of the connection can be improved through proper design regardless of the low toughness of the wet weldment.