Shaft protection warning

DNV has warned of the need to protect the surfaces of tailshafts and intermediate shafts during maintenance work. It highlights the example of a high-tensile steel intermediate shaft that sheared during operation. Subsequent metallurgical investigations determined that the probable cause of the shear was a weld strike to the surface during an earlier maintenance program. “Quenching of the weld pool caused a cold crack and initiated subsequent torsion fatigue failure from that initiation point,” concludes DNV. DNV says high tensile steel shafts are more susceptible to such damage and therefore protecting their surface during maintenance is particularly relevant. It recommends wrapping the shaft with protective tape and additional measures such as using fire resistant screens during maintenance.