Objectives of CAVT : -

  • To determine the areas/ locations at which velocities are higher than respective plane average velocity.
  • To determine the area of air ingress in to second pass of the boiler.
  • To determine the gas flow pattern in the respective zones.
  • To determine the MCR velocities at respective zones.
  • Easily deployed.

Process of CAVT : -

  • Taking velocity measurements at predetermined planes and locations
  • Computing plane average velocity
  • Reducing velocity data to normalize velocity
  • Study & analysis of normalized velocities
  • Locating high velocity locations
  • Mapping of high velocity over erosion prone areas
  • Determining areas requiring velocity corrections
  • Design, Manufacture, Supply & Install Erosion Control Device (Expanded Metal Screens).
  • Carry out Post CAVT


  • CAVT explains why fly ash erosion is still the most important failure mechanism.
  • The high velocities will be reduced near average normalize velocities at various Zones.
  • To determine the gas flow pattern in the respective zones.
  • Due to reduction of high velocities, tube erosion will be reduced in such areas.
  • The boiler can run continuously and reduce the generation loss which was earlier on accounts of tube leakages in second pass.