Method and device for long-range guided-wave inspection of fire side of waterwall tubes in boilers

A method for long-range torsional guided-wave inspection of the fire side of a waterwall tube, the method comprising the steps of:

• providing and positioning a plate magnetostrictive sensor probe over an external surface of the waterwall tube along a portion of a circumference of the tube;
• providing and activating an electromagnet across the plate magnetostrictive sensor probe to draw and maintain the sensor probe into contact with the external surface of the waterwall tube;
• and
• connecting the magnetostrictive sensor probe to magnetostrictive sensor instrumentation and generating and receiving interrogation signals into and from the waterwall tube under inspection.

A method for long-range torsional guided-wave inspection of the fire side of a waterwall tube, the method comprising the steps of:

• preparing the external surface of the waterwall tube to provide mechanical compliance between the waterwall tube and a sensor probe to be placed in contact therewith;
• providing and positioning a plate magnetostrictive sensor probe over the prepared external surface of the waterwall tube along a portion of a circumference of the tube;
• providing a strip of magnetostrictive material between the plate magnetostrictive sensor probe and the prepared external surface of the waterwall tube;
• providing and positioning a compressible/expandable bladder over the plate magnetostrictive sensor probe;
• providing and positioning a rigid inverted U-shaped frame over the compressible/ expandable bladder and plate magnetostrictive sensor probe;
• providing and activating an electromagnet across the plate magnetostrictive sensor probe to draw and maintain the sensor probe into contact with the external surface of the waterwall tube;
• establishing a bias magnetic field within the magnetostrictive strip to optimize torsional wave magnetostrictive sensor operation using the activated electromagnet;
• and
• connecting the magnetostrictive sensor probe to magnetostrictive sensor instrumentation and generating and receiving interrogation signals into and from the waterwall tube under inspection.