Turbine blade damage can have devastating effects on production and on finances. When in-service degradation was suspected in the industrial gas turbine of one of TWI's clients it could have cuased decreasing blade life and costly replacements.
Within hours of the discovery TWI had taken the brief to determine if the operating conditions were causing unusual degradation and recommend remedial action. Several recently decommissioned turbine blades, each of more than 100 000 hours service were forwarded to Cambridge.
Using detailed visual examination techniques, a binocular microscope and fluorescent penetrant, the parts were scrutinised. Chemical analysis and X-ray mapping was undertaken as well as mechanical testing and metallographic inspection.
The blades supplied revealed no degradation, so no remedial action was recommended. They were within specification and had not suffered hot corrosion. This indicated that they could expect good life from the replacement blades.