ISSN: (Online) 2321 -4155
ISSN: (Print) 2320 -7000

JOURNAL OF INDIAN RESEARCH
VOLUME : 3, ISSUE : 2, April-June, 2015 (ISSN No. : 2321-4155)
 
EXPERIMENTAL STUDIES ON THE EROSION RATE OF LOW CARBON STEEL BANK TUBES OF PROCESS BOILERS IN STRAIN-HARDENED AND SUB- CRITICAL ANNEALED CONDITION
T.S.G.Narayannen & Dr. Ashish Agarwal
 
ABSTRACT
Erosion of bank tubes in bi-drum boilers is one of the critical factors leading to the shutdown of power plants. It has been found that more than 25% of all boiler tube failures worldwide are caused by fly ash erosion. Previous studies have established that the major factors influencing the fly ash erosion process are the velocity, impact angle, feed rate and particle size of fly ash. In the present study, the effect of heat treatment conforming to ASME code, during fabrication of bank assembly carbon steel tube conforming to specification ASME SA-192, on erosion rate is analyzed taking into account the factors of velocity, impingement angle, feed rate and particle size of fly ash. Considering the fabrication of the SA-192 tubes which involves cold bending of tubes which in turn leads to strain hardening, bent-tubes with sub- critical annealed condition and bent-tubes without sub- critical annealing condition have been studied. The experiments were conducted in the air jet erosion test rig at M/s. Bharat Heavy Electricals Limited, Tiruchirappalli, India. It has been found that during fabrication of the tubes, bent-tube with sub -critical annealing when compared to bent-tube without sub- critical annealing condition has less erosion rate for all velocities, impact angles, feed rates and different particle sizes of fly ash. This characteristics in bent-tube with sub -critical annealing emerges due to the higher ductility of these tubes compared to the tubes which were not sub- critically annealed.
 
KEYWORD
Bank tube, Fly ash; Strain hardening; Sub critical Annealing; tube erosion.
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