Examination of cracking in boiler tubes
Background
A manufacturer of steam raising boilers encountered a series of cracking problems in a number of boiler tubes that had seen no more than 18 months service. TWI was asked to examine some failed tubes, determine the cause of failure, and with this information make recommendations on how eliminate the problem.A programme involving:
- fractographic examination of surfaces to confirm the cause and mode of failure, and
- comparison of microstructure between failed and unfailed components
|
Micrograph of cracks in the tube wall |
The cracking was found to have arisen from thermal fatigue, a result of the normal thermal operating cycle of the boiler. The material, although of variable quality, was not the cause of failure. The report concluded that the failures were a result of high thermal stresses due to poor design.
Non-nuclear case studies index
Copyright © 2001, TWI Ltd
Information and advice from TWI and its partners are provided in good faith and based, where
appropriate, on the best engineering knowledge available at the time and incorporated into TWI's
website in accordance with TWI's ISO 9001:2000 accredited status. No warranty expressed or implied
is given regarding the results or effects of applying information or advice obtained from the
website, nor is any responsibility accepted for any consequential loss or damage.