Tube inspection apparatus.

摘要

In electromagnetic inspection apparatus for detecting, in-situ, the location and character of flaws in a relatively long, thick-walled small bore tube (1) of a heat exchanger, a resultant magnetic field (Ba) of selected direction and magnitude is induced in the wall of the tube by the vector addition of magnetic fields (Bs, Bc) produced by two magnetic field generators (10, 16), at least one of which (10) is carried by a scanner (4) for traversing the tube and having an array of sensors (22) mounted in close proximity to the wall of the tube (11) for generating a unique signal as the scanner passes a flaw in the tube.