Gas Turbine Casing Flange Section Replacement for Crack Repair
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Solution Overview
Problem
Existing methods for repairing cracks in gas turbine engine casing flanges, particularly those extending towards the case wall, are inadequate as they are not effectively addressed by conventional weld repair techniques, often requiring complete flange replacement.
Innovation Solution
A method involving the removal of the affected section of the flange and its replacement with a pre-machined part that is welded into place, allowing for effective repair without full flange replacement, using suitable welding processes like Gas Tungsten Arc, electron beam, or laser welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional weld repair techniques are used on cracks extending towards the case wall, then repair complexity is reduced, but repair effectiveness deteriorates
Solution Approach 1:
The flange is divided into two separate parts: the case wall portion and the bolt hole strap portion. This segmentation allows the cracked section to be removed and replaced independently, enabling effective repair of cracks extending toward the case wall while maintaining manageable repair complexity through modular construction
Solution Approach 2:
The invention changes the structural configuration parameter of the flange from a monolithic piece to an assembled structure with distinct segments. This parameter change enables the replacement of only the affected portion rather than the entire flange, improving repair effectiveness while controlling complexity
2Reliability
If the entire flange is removed and replaced, then crack repair effectiveness is improved, but maintenance cost and downtime increase
Solution Approach 1:
By segmenting the flange into replaceable portions, only the cracked section needs to be removed and replaced rather than the entire flange. This ensures complete removal of the crack while significantly reducing maintenance downtime and cost compared to full flange replacement
Solution Approach 2:
The cracked portion of the flange is extracted and removed from the assembly. This extraction allows the defective section to be completely eliminated while preserving the sound portions of the flange, achieving effective crack repair with minimal component replacement
3Reliability
If the entire flange is removed and replaced, then crack repair completeness is improved, but material loss increases
Solution Approach 1:
Segmenting the flange allows selective replacement of only the cracked portion, ensuring complete crack removal while preserving the majority of the original flange material. This eliminates the material loss associated with discarding entire flanges
Solution Approach 2:
Only the defective portion of the flange is discarded, while the remaining sound portions are recovered and retained in service. This selective discarding approach achieves complete crack repair while minimizing material loss
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables efficient and effective repair of cracks in gas turbine engine casing flanges, extending the lifespan of the component without the need for complete replacement, thus reducing maintenance costs and downtime.
Implementation Method 1
The new section is then welded to the remainder of the casing flange
Implementation Method 2
using suitable welding processes like Gas Tungsten Arc, electron beam, or laser welding
Implementation Method 3
using suitable welding processes like Gas Tungsten Arc, electron beam, or laser welding
Implementation Method 4
using suitable welding processes like Gas Tungsten Arc, electron beam, or laser welding
Data Source
Figure 1
Figure 2A~3D
Figure 3A~3C
AI summary
A method of repairing a casing for a gas turbine engine, wherein the casing has a wall extending generally axially, and between at least one radially extending flange, the radially extending flange being formed with a plurality of bolt holes, includes the steps of removing a portion of the flange including at least one bolt hole. The removed portion is associated with a defect and a remaining portion of the flange includes at least one non-removed bolt hole. A replacement portion is obtained to replace the removed portion. The replacement portion is secured in an opening left in the flange by the removed portion. A repaired gas turbine engine casing is also disclosed.