1. Planed or smooth, wavelike contours aligned perpendicular to the steam flow

         2. Flat area on the side near the soot blower

         3. Thin wall or pinhole failure due to rapid wastage of tube surface

         4. Thick wall failure (creep) due to slow tube wastage 

         5. Little or no ash deposits in blown areas

         6. Thermal fatigue present where entrained water is present in blowing medium  

         7. Fresh rust forms on tubes within hours of wash down  

         8. Protective scale has been removed  

         9. Seen in a circular pattern around soot blowers  

         10. Found at corners where the blower is blowing into the corner  

         11. Found at the top of the slope areas in the furnace  

         12. Increased oxidation usually found in washed areas  

         13. Grooved or gouged tubes due to blowing steam eddying  

         1. Improper location or operation of a soot blower 

         2. Malfunction of the soot blowing system

         3. Operation of a soot blowing system with condensed water in the media

         4. Blowing pressure that injects a large amount of ash at a high velocity 

         5. Blower is inserted incorrectly

         6. Blower close to a corner or wall protrusion can result in accelerated tube wear 

         7. Blower may cause a high velocity stream of condensed water droplets

         8. Physical abrasion and accelerated oxidation resulting in metal loss

         9. Fly ash entrained in the stream will aid in erosion, thinning to rupture

         10. A malfunctioning condensate removal system in the steam supplies

         11. Poor alignment of adjacent tubing

         12. Pre blow of the soot blower

         13. Inadequate shielding

         14. Stuck in one position

         15. Missing or damaged blower lance head

         16. Excessive use of soot blowers

         17. Insufficient steam temperature

         18. Excessive blowing pressures

         19. Misalignment of blower nozzle

Typically occurs in the direct path of a wall blower or retractable blower discharge. Also occurs in the furnace where there is direct impingement from wall blowers near furnace corners, slope areas and division walls. Occurs at any tube or tubes that are bowed out of plane allowing exposure to the soot blower. Look at any intersection of tubing in line with the discharge path of a soot blower. Occurs usually in the first tubes adjacent to the soot blower opening, where condensate will first vent. Check inside opening (bent) tubes for pre-blow or blowing of the soot blower before it clears the tube wall.  NOTE: Leading tube erosion in the soot blower may sometimes only be detected through UT. Occurs in the direct path of retractable soot blowers in the hottest (outlet) sections of adjacent Reheaters or Superheaters. Occurs in any location the sootblower can drive wet steam or fly ash. This includes economizers, Superheaters, and Reheaters both vertical and horizontal in orientation.

The root cause can be verified by investigating the operation of the system.  Malfunction or misalignment of the soot blower device can be revealed by visual means. Malfunction of the system can be detected by measuring blowing pressure, testing moisture traps, or checking travels and sequence times. 

         Convection Pass

         Economizer

         Reheater

         Superheater

         Water walls

Establish a soot blower inspection and operation team.  Corrective actions involve surveillance and improved maintenance of soot blowers and soot blower systems.  Establish any necessary boiler design modifications due to operational changes (i.e. fuel, Low Nox burner conversions).  Visual examinations of sootblower operation and calibration of system components during boiler over-haul periods provide long-term actions for the prevention of failures by soot blower erosion.  Develop repair criteria based on minimum wall thickness and wastage rates.