Enhanced sensitivity detection of defects in gas turbine blades of aero-engine and hairpin tubes of heavy water plant using microfocal radiography

Abstract

This paper reports on the microfocal radiography (MR) procedure for detection of shrinkage defects and imaging of internal parts of the cooling channels of aero-engine gas turbine blades. MR, with inherent magnification, has been used for evaluation of blisters in hairpin tubes subjected to service conditions. The results are compared with the conventional radiography technique and it is found that MR can provide additional features, such as internals in turbine blades, shrinkage defects etc. In the case of hairpin tubes, it has been found that microfocal radiography is an ideal technique for detecting defects such as blisters and branching cracks with better sensitivity than conventional radiography. Results also show that MR is the best choice for quality control of aero-engine turbine blades at the production stage in order to have control over the process parameters and for failure analysis of hairpin tubes used in Heavy Water Plants (HWP).