Sand balsting effect on boiler tube

CAUSES :
TOO HIGH ID DRAFT THAT EFFECT SAND BLASTING ON THE TUBE.

SOOT BLOWER NOZZLE MISALIGNED CAUSING DIRECT IMPINGEMENT TO THE TUBE.

PREVENTIVE MEASURES :
BALANCE THE ID FAN TO FURNACE DRAFT OF - ½ TO 1 INCH OR 10 TO 20 MM/h20.
CHECK SOOT BLOWER NOZZLE ALIGNMENT PERIODICALLY AT LEAST HALF YEARLY.