Analysis of bending properties of structures repaired by composite materials with girth weld defects
In order to research and determine the repair effect of composite material repair method against bending load of girth weld defects,the girth weld of X80 pipeline(pipe diameter 1 016 mm,wall thickness 18.4 mm)was prepared by low hydrogen electrode shielded manual arc welding(SMAW)+self-protected flux-cored wire semi-automatic welding(FCAW)welding process,and the root crack(length 350 mm,depth 9 mm)of double-step girth weld was processed by electrical discharge machining(EDM).A composite material structure of grade E high-strength two-way fiberglass fabric+epoxy resin with excellent properties was prepared by vacuum-assisted resin injection(VARI),and a full-scale four-point bending test was carried out to compare the bending load resistance of the defective girth weld before and after repair.The results show that the bending load resistance of the girth weld enhanced by the test composite structure(thickness 40 mm,length 1 000 mm)is about 21%of the measured yield strength of the pipe,which has limited capability for enhancement of bending resistance.The research results have a reference significance for guiding the formulation of repair strategies for girth weld defects.
pipegirth weldcomposite materialrepair effectfull-scale bending test