Pulsed Eddy Current Testing of Inner Wall Flaws in Pipe under Insulation

AbstractThe localized inner wall corrosions in the pipe under insulation are especially hazardous to pipelines. An inspection system is designed to detect inner wall flaws in pipe based on pulsed eddy current technique. Simulation specimens with large area thinning, localized grove-like corrosions and pit-like corrosions are machined, and probes are designed and manufactured. A series of experiments are performed to optimize testing parameters and improve detection sensitivity. The experiments show that the system can detect 10 percent thinning of wall under insulation when the thickness of pipe and insulation is respectively 10mm and 110mm. The detection accuracy can meet the requirement in the inspection of pressure pipeline. The system can also detect some localized corrosions under insulation