NUMERICAL STUDY ON CAPABILITIES CONSTRUCTIONS OF ELECTROMAGNETIC ACOUSTIC TRANSDUCERS (EMAT) WITH PERMANENT MAGNETS FOR INLINE INSPECTION OF PIPELINE 6'

摘要

Pipeline operators are paying particular attention to the integrity of pipes. Currently the most common methods used for in-line pipeline inspection is Magnetic Flux Leakage (MFL) and ultrasound techniques. EMAT method is a new method, based on a generation of ultrasonic waves. Traditional ultrasonic technologies (UT) based on piezoelectric transducers are only applicable with liquid couplant between the transducer and the pipe wall. EMAT design typically consists of a system of permanent magnets and the conductor. Induced currents interact with the magnetic field of the permanent magnets create a Lorentz force in the testing object, causing ultrasonic waves. EMA method does not require the presence of fluid between the transducer and the object under test. Also, only EMAT system allows detecting stress corrosion cracking (SCC), to predict the future cracks.