Corrosion Fatigue Tests on Welded Tubular Joints

The corrosion fatigue performance of welded tubular joints is recognized as one of the most important factors in the design of offshore structures. Because of the cost of such tests it has been practice to carry out tests on tubular joints in air and to perform corrosion fatigue tests on simple welded joints. Thus very few corrosion fatigue tests have been carried out on tubular joints. The present paper describes the results of fatigue tests which have been carried out on welded tubular joints both in air and in a sea water environment. The specimens were tubular K and KT-joints with chord dimensions of 168 mm diameter and 6 mm wall thickness. The tests were carried out under out-of-plane bending. The corrosion fatigue tests were carried in sea water at 10° C at a frequency of 10 cycles per min, which is typical of wave periods. The specimens were not cathodically protected. The fatigue results in air and sea water are compared, and discussed in connection with the current fatigue design S-N curves for tubular joints contained in various standards.