On-line Crack Monitoring Technology of Steam Cooler Girth Welding Based on the Acoustic Emission Principle

Abstract

Micro-cracks can easily form in the girth welding zone of a steam cooler. The presence of these cracks in the alternating load will produce fatigue growth and cause equipment failure. Acousitc emission on-line monitoring of the girth weld is proposed to ensure the healthy and stable operation of the steam cooler. Attenuation testing of the acoustic emission waveguide and acoustic emission characteristic testing of weld crack propagation are methods created to mitigate acoustic emission signal attenuation problems in on-line monitoring technology. Acoustic emission on-line monitoring is used to collect and process the attenuation of acoustic emission signals under varying waveguides. Results illustrate that accurate design of the waveguide rod structure can effectively reduce acoustic emission signal attenuation. To verify the feasibility of acoustic emission on-line monitoring technology, the acoustic emission characteristics of fatigue crack propagation in weld cracks were investigated using the acoustic emission on-line monitoring method. A large number of acoustic emission signals were collected during the fatigue propagation of weld cracks using this technique. This finding verifies the suitability of on-line acoustic emission monitoring technology for on-line monitoring of cracks in the girth weld of a steam cooler.