Reinforcing the barrier

摘要

Dr. Michael Fletcher, Delta Consultants, UK, discusses a range of solutions designed to maintain the corrosion resistance of pipe welds. Butt welding in large diameter pipes brings with it several singular problems, not least the effective protection of the weld deposit and maintaining control and consistency of quality during deposition over the long joint lengths involved. Less evident is protection of the exposed internal side of the weld from oxidation. Alloys containing chromium, added for resistance to corrosion and to improve mechanical properties, are particularly vulnerable. These include a range of nickel-based materials and the steel alloys developed for creep resistance, but the entire range of ferritic, martensitic, and austenitic stainless steels can suffer from significant reduction in corrosion resistance and mechanical strength due to loss of chromium by oxidation during welding.