LOCALISED CORROSION ON OFFSHORE TUBULAR STRUCTURES: INSPECTION AND REPAIR CRITERIA

Localised corrosion damage may be detrimental to the fatigue strength of offshore steel structures. An investigation was carried out in order to assess the effect of corrosion pits on the fatigue strength of planar and tubular welded joints. Pitting corrosion was selected in accordance with the geometry of pits observed in offshore structures. Tests on planar specimens were carried out in air and in natural sea water with and without cathodic protection. Tubular joints were tested in air. Fatigue notch factors were derived on the basis of nominal and net section stresses. The overall effect of pitting corrosion on the fatigue strength of tubular welded structures was assessed. Parts of the structures in which pitting corrosion would be of particular importance with respect to structural integrity were assessed. The paper concludes with a set of criteria for inspection of offshore structures with respect to detrimental effect of corrosion pits.