Abstract: For given crack size and load,structure integrity assessment procedure,(SINTAP) sponsored by the European Commission was applied to assess the overmatching welded joints of the API 5L X65 pipeline steel with surface flaw at the weld toe.The assessment was carried out according to limit load solutions and the CTOD,(crack tip opening displacement) test result.The failure line of level 2 of the weld was derived from the tensile test results.The result of the assessment showed that the point,(L_r,K_r) is located within the failure line of analysis level 2.So the overmatching welded joint of the pipeline is safe.This study laid the foundation of application of SINTAP to pipeline structure assessment.