Welding and Weld Improvement
Fatigue damage can result in cracking, fracturing and ultimately disconnection. Welding is one solution and can be performed offshore in wet or dry conditions.
Depending on access and orientation, dry welding offers the ability to carry out high quality welds because of the increased control over environmental conditions. Certified welder divers perform dry welding from within a sealed, underwater chamber that is specially fabricated to fit around the damaged area.
Wet welding can be carried out quickly, as an underwater chamber is not required. However, the quality and integrity of wet welds has been questioned and is not accepted in all jurisdictions.
Weld hammer peening
A hammer tool is used to plastically deform the surface layer of the steel weld metal, leaving a compressive residual stress at the surface which allows improved fatigue lives to be realised.
This technique is used to arrest fatigue cracks by excavating a smooth-shaped trench in the cracked metal using a grinding disc or burr grinding tool. Subsequent re-welding or encapsulation by a clamp may be required.