Research on Residual Tensile Strength of Tubing with Typical Corrosion Defects

The influence of three kinds of corrosion defects on the residual strength of old tubing is studied with the use of the finite element analysis software and tubing property evaluation in practice.The analysis results show that when old tubing contains corrosion defects with spherical, conical or cylindrical shape the tensile strength of the corrosion pit with the largest diameter is 1.8%, 1.0%or 1.9%lower than that of the corrosion pit with the smallest diameter respectively and all of which still meet the requirement of API Bull 5C2-1999;the old tubing still have relative high tensile strength when its corrosion pit depth is less than 30%of its nominal wall thickness.