Automated Ultrasonic Generating Bank (near Drum) Inspection System
Tube Cracking Detection

The drawing below depicts the area where tube cracking is usually found at the near drum level in the generating bank section of a boiler.

INDUSTRY PROBLEM - TUBE CRACKING

Tube cracking occurs as a result of uncontrolled cyclic vibrational stress. This can happen in both the upper and lower drum levels.

The figure above is a computer display of a C-scan of a tube (unrolled) with the accompanying end and side B-scans. It shows two flaws at 3 o'clock and 9 o'clock positions. The color-codes chosen in the C-scan varies from red (100% flaw amplitude) to dark blue (baseline).

The figure above is a computer display of B-scans of the same tube. The top graph shows all the scans of the tube and the bottom graph shows the single scan where the maximum flaw amplitude was found. The maximum flaw amplitude is recorded in the box on the top right corner of each graph.

3-D Image of Longitudinal Notches on Boiler Tubes
(Simulated Longitudinal Cracking)

The 3-D image below is taken from an actual scan of a boiler tube with 3 longitudinal notches (to simulate longitudinal cracks). The data from the scan obtained was then fed into a 3-D imaging program.


CLICK ON IMAGE TO ENLARGE

The image shows the 3 dimensions - rotation, axial distance and signal amplitude. Rotation is expressed in degrees for the circumferential location with reference to 0 degrees at the 12 o'clock position. The axial distance for this scan shows only a 2 inch scan but our system is capable of doing up to 6 inches for near drum boiler tube crack inspection. The color-codes chosen for signal amplitude varies from red (100% flaw amplitude) to light purple (baseline).

For further information, contact
Stasuk Testing & Inspection Ltd
8955 Fraserwood Court
Burnaby,
British Columbia V5J 5H7,
Canada
Tel: 604-420-4433 Fax: 604-420-2685