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Posted by SOVAN on May 12, 2002 at 00:34:57:
We have BHEL make VV 40 boiler of 180 T/hr, 96 Kg/cm2 and 510ºC (Natural circulation, corner fired boiler). Recently we have waterwall tube failure of fish mouth opening type. Location of leakage is on the roof tube (riser). At the time of failure boiler was on full load i.e. 185 T/hr, 500ºC and 100kg/cm2 pressure. Drum level was quite normal. Suddenly tube failed and boiler tripped on flame failure and after leakage water level fell down.
Thicknesses of the surrounding tubes were found normal. Tube failure occurred after 45 days of operation after annual overhauling and inspection.
How overheating can take place in such location? (Preliminary reason of tube failure was starvation) What are the probable causes of starvation at this location (35th tube out of 83 tubes).
Will appreciate a reply. Thanks.