A NEW HPC AIRFOILS CONTROL PROCEDURE HAS BEEN MASTERED
The actual purpose of non-destructive inspection is detection of parts failures at early stages of their development. A specific feature of industrial gas turbine operation is considerable time-between-overhauls that imposes additional requirements on the effectiveness of gas turbine non-destructive inspection.
We asked Alexander Vakhotin, Head of Non-Destructive Inspection Department to tell us about new methods of non-destructive inspection, developed by Aviadvigatel specialists.
Non-Destructive Inspection Department of Aviadvigatel OJSC has achieved a major improvement in effectiveness of on-site Eddy current testing of PS-90GP-2 HPC 0-stage blades anti-vibration shrouds by fatigue cracks detection at early stages of their development.
Previously during the anti-vibration shrouds Eddy current testing the line of scanning by a probe could be located away from the shroud contact edge up to 4 mm, that would make it difficult to detect a crack at early stage of its development.
To get a positive result it was necessary to bring the scanning line as near as possible to the shrouds junction. To do this the Inspection Department specialists developed and produced a special fixture and a new design of Eddy current probe.
The scanning line maximum approach to the shrouds junction and accuracy of the fixture installation on shrouds is achieved by attaching the fixture in shrouds fillets directly on their junction. This ensures that the maximum distance between the scanning line and the shrouds junction is not more than 2 mm. This is 2 mm less than provided by the present inspection procedure and makes it possible to detect a crack at earlier stage of its development.
Scanning accuracy is achieved due to guiding slots in the fixture. Within these slots an Eddy current probe is moved.
It is necessary to note that advanced methods of inspection allow reducing the required labor because one model installation allows inspection of both adjacent shrouds.
Today Eddy current testing of blades anti-vibration shrouds is at the stage of its implementation. Specialists of Customer Support Department of Perm Engine Company have passed training courses on new inspection methods and the improved inspection procedures were validated both at operators` facilities and the production plant assembly shop.
