Ultrasonic　guided　waves　(UGWs)　of　T(0,1)　mode　were　generated　by　magnetostrictive　sensors　(MsS)　to　perform　36-day　monitoring　of　a　defective　welded　pipe　elbow.　A　hydrochloric　acid　pool　was　employed　to　accelerate　the　corroded　defect　accumulation　process,　and　a　total　of　11　defect　levels　were　recorded.　The　envelope　of　UGWs　was　found　to　be　insufficient　to　indicate　the　defect　level　lower　than　6　due　to　the　instability　of　monitoring　signals.　To　achieve　the　high-quality　display　of　the　corrosion　accumulation　process,　the　energy　of　concerned　wave　packets　was　introduced　to　act　as　a　new　indicator.　To　suppress　the　influences　of　sensor　deterioration,　the　energy　of　wave　packet　corresponding　to　the　elbow　region　(E-defect)　was　divided　by　the　energy　of　wave　packet　representing　the　feature　reflectors　(such　as　obstacle,　free　end　and　welds)　in　the　straight　pipe　section.　The　compensated　energy　of　wave　packet　demonstrated　the　stepped　growth　at　each　level　of　defect　under　the　operation　frequency　of　64　kHz.　The　smoothed　curve　of　E-defect/E-weld　was　the　self-compensation　to　MsS　deterioration　and　could　achieve　the　highly　sensitive　display　of　the　corrosion　defect　accumulation　process　since　the　value　of　E-defect　increased　at　the　cost　of　subsequent　weld　waves＇　energy.