Wide Gap Braze Repair of Gas Turbine Blades and Vanes—A Review

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Xiao Huang ◽  
Warren Miglietti
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Life Cycle Cost ◽  
Turbine Blades ◽  
Advanced Materials ◽  
Gas Turbine Blades ◽  
Rare Elements ◽  
Compositional Choices ◽  
Useful Life ◽  
Wide Gap

Gas turbine blades and vanes in modern gas turbines are subjected to an extremely hostile environment. As such, sophisticated airfoil designs and advanced materials have been developed to meet stringent demands and at the same time, ensure increased performance. Despite the evolution of long-life airfoils, damage still occurs during service thus limiting the useful life of these components. Effective repair of after-service components provides life-cycle cost reduction of engines, and as well, contributes to the preservation of rare elements heavily used in modern superalloys. Among these methods developed in the last four decades for the refurbishment and joining of superalloy components, wide gap brazing (WGB) technology has been increasingly used in the field owing to its ability to repair difficult to weld alloys, to build up substantially damaged areas in one operation, and to provide unlimited compositional choices to enhance the properties of the repaired region. In this paper, the historical development of wide gap repair technology currently used in industry is reviewed. The microstructures and mechanical properties of different WGB joints are compared and discussed. Subsequently, different WGB processes employed at major OEMs are summarized. To conclude this review, future developments in WGB repair of newer generations of superalloys are explored.

Repair of Advanced Gas Turbine Blades

2007 ◽  
Author(s):  
Reiner Anton ◽  
Brigitte Heinecke ◽  
Michael Ott ◽  
Rolf Wilkenhoener
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Life Cycle Cost ◽  
High Efficiency ◽  
High Reliability ◽  
Turbine Blades ◽  
Cost Effective ◽  
Complex Nature ◽  
Thin Wall ◽  
Advanced Technologies

The availability and reliability of gas turbine units are critical for success to gas turbine users. Advanced hot gas path components that are used in state-of-the-art gas turbines have to ensure high efficiency, but require advanced technologies for assessment during maintenance inspections in order to decide whether they should be reused or replaced. Furthermore, advanced repair and refurbishment technologies are vital due to the complex nature of such components (e.g., Directionally Solidified (DS) / Single Crystal (SC) materials, thin wall components, new cooling techniques). Advanced repair technologies are essential to allow cost effective refurbishing while maintaining high reliability, to ensure minimum life cycle cost. This paper will discuss some aspects of Siemens development and implementation of advanced technologies for repair and refurbishment. In particular, the following technologies used by Siemens will be addressed: • Weld restoration; • Braze restoration processes; • Coating; • Re-opening of cooling holes.

Acoustic Thermography Testing of Industrial Gas Turbine Blades in the Service Stage

2008 ◽  
Author(s):  
Mattias Broddega˚rd ◽  
Christian Homma
Keyword(s):  
Gas Turbine ◽  
Test Object ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Medium Size ◽  
Testing Time ◽  
Testing Technique ◽  
Ir Camera ◽  
Gas Turbine Blades ◽  
Industrial Gas Turbine

Gas turbine blades are operating under very demanding conditions. In modern industrial gas turbines, the rotating blades and the guide vanes of the first stages are hollow to allow internal cooling. This means that there is a possibility of having crack initiation on the internal surface of the components. Due to the complex casting geometry, this type of defects is very difficult to detect with conventional nondestructive testing techniques such as ultrasonic and radiographic testing. Siemens has developed a new non-destructive testing technique based on acoustic thermography, SIEMAT. The test object is energized by an ultrasonic excitation device. Due to the vibrations, a very slight heating will develop at cracks in the test object. The local increase of temperature is captured by a highly sensitive IR camera. The SIEMAT technique is capable of detecting both surface-breaking and internal cracks, including cracks under coatings. The testing time is very short, and the IR sequences are recorded for subsequent analysis. A major advantage for service applications is that the technique is mostly sensitive to closed defects such as cracks, since open defects where no contact between the faces is present, for example pores and scratch marks, will not cause any heat generation. Siemens is currently implementing the SIEMAT technique for assessment of service-exposed turbine blades from medium size gas turbines, which are due for reconditioning. By being able to verify that no internal cracks are present, the reliability of the reconditioned blades will be increased. This paper describes the SIEMAT testing technique, and the results obtained when applied on service-exposed industrial gas turbine blades.

scholarly journals Investigation of the Relationship between Degradation of the Coating of Gas Turbine Blades and Its Surface Color

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7843
Author(s):  
Mariusz Bogdan ◽  
Józef Błachnio ◽  
Artur Kułaszka ◽  
Dariusz Zasada
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Protective Coatings ◽  
Turbine Blades ◽  
Operating Time ◽  
Surface Color ◽  
Metallographic Examination ◽  
Gas Turbine Blades ◽  
Study Results ◽  
The Relationship

This article presents issues concerning the relationship between the degradation of the coating of gas turbine blades and changes in the color of its surface. Conclusions were preceded by the determination of parameters characterizing changes in the technical condition of protective coatings made based on a metallographic examination that defined the morphological modifications of the microstructure of the coating, chemical composition of oxides, and roughness parameters. It has been shown that an increased operating time causes parameters that characterize the condition of the blades to deteriorate significantly. Results of material tests were compared with those of blade surface color analyses performed using a videoscope. Image data were represented in two color models, i.e., RGB and L*a*b* with significant differences being observed between parameters in both representations. The study results demonstrated a relationship between the coating degradation degree and changes in the color of the blade’s surface. Among others, this approach may be used as a tool to assess the condition of turbine blades as well as entire gas turbines.

scholarly journals Computer Predictions of Erosion Damage in Gas Turbines

1987 ◽  
Author(s):  
A. F. Abdel Azim El-Sayed ◽  
A. Brown
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Iterative Procedure ◽  
Pressure Coefficient ◽  
Turbine Blades ◽  
Engine Performance ◽  
Erosion Damage ◽  
Gas Turbine Blades ◽  
Coefficient Distribution ◽  
Blade Section

In this article an iterative procedure is presented for estimating erosion in axial gas turbine blades. The procedure is applied to a two stage turbine and the erosion is estimated for a 12,000 hour engine running time. The effect of the erosion on engine performance is estimated through changes in pressure coefficient distribution around a blade section.

Repairing of Degraded Hot Section Parts of Gas Turbines by Cold Spraying

2009 ◽  
Vol 417-418 ◽  
pp. 545-548 ◽  
Author(s):  
Kazuhiro Ogawa ◽  
Takahiro Niki
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Cold Spraying ◽  
Combined Cycle ◽  
No Oxidation ◽  
Maintenance Cost ◽  
Temperature Oxidation ◽  
Gas Turbine Blades

Hot section parts of combined cycle gas turbines are susceptible to degradation due to high temperature creep, crack formation by thermal stress, and high temperature oxidation, etc. Thus, regularly repairing or replacing the hot section parts such as gas turbine blades is inevitable. For this purpose, revolutionary and advanced repair technologies for gas turbines have been developed to enhance reliability of the repaired parts and reduce the maintenance cost of the gas turbines. The cold spraying process, which has been studied as not only a new coating technology but also as a process for obtaining a thick deposition layer, is proposed as a potential repairing solution. The process results in little or no oxidation of the spray materials, so the surfaces stay clean, which in turn enables superior bonding. Since the operating temperature is relatively low, the particles do not melt and the shrinkage on cooling is very low. In this study, the cold spraying conditions were optimized by taking into account the particle kinetic energy and the rebound energy for application in repairing gas turbine blades. A high quality cold-sprayed layer is that which has lowest porosity; thus the spraying parameters were optimized to achieve low-porosity layer, which was verified by scanning electron microscopy (SEM).

Finite Element Modeling of the Eddy-Current Inspection of Land-Based Gas Turbine Blades

2001 ◽  
Author(s):  
Hiroyuki Fukutomi ◽  
Takashi Ogata
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Gas Turbine ◽  
Eddy Current ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Combined Cycle ◽  
Multiple Cracks ◽  
Gas Turbine Blades ◽  
Element Modeling

There has been a growing need in recent technology of gas turbines in combined cycle to assess the remaining life of high temperature components. It is also required that the nondestructive assessment be more accurate in maintaining combined cycle plants. This paper describes the use of a simulator solving forward and inverse problems under eddy current testing, in parametric studies of inspection parameters for 1100°C-class gas turbine blades in terms of test probe capabilities, frequencies and signal interpretation. The simulator is based on a differential formulation constructed with a magnetic vector potential and a 3-dimensional edge-based finite-element modeling method. Its features are forming coils and defects independent of a whole finite element model, very fast eddy current response predictions, and identifications of electromagnetic properties. Using the simulator, optimal sensor types and test frequencies are determined in terms of assessment of degradation, selectability between surface-breaking and subsurface cracks, reconstruction of crack profiles, and detection of multiple cracks.

scholarly journals Sistema de información para la caracterización de imágenes de desgaste en álabes de rotor de una turbina de gas

2020 ◽  
pp. 27-34
Author(s):  
Luz Yazmín Villagrán-Villegas ◽  
Miguel Patiño-Ortiz ◽  
Luis Héctor Hernández-Gómez ◽  
Víctor Velázquez-Martínez
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Mechanical Failure ◽  
Total Loss ◽  
Mechanical Equipment ◽  
End User ◽  
Gas Turbine Blades ◽  
The Difference

In Mexico, the end user of gas turbines (PEMEX), in the NRF standard, requests the Goodman and Campbell diagrams for the acquisition of new turbo machinery. However, the requirement of the diagrams is not reported when the turbine is sent for overhaul. In this research article, it is suggested that the end user when carrying out a wear analysis of a turbine blade, know precisely the conditions of a blade in case of total loss of the machine or in conditions in which they send one or several turbine discs to the manufacturer and the conditions that receives after overhaul the discs. Wear and friction are the most adverse factors in reducing the useful life of mechanical equipment. The loss of a relatively small amount of material, in certain critical locations of any mechanical part, can make the difference between the damage and the good functioning of the gas turbine, so this research aims to characterize images of a turbine blade with in order to identify any wear or mechanical failure; analyzing the responses to deterministic and non-deterministic variables, looking for responses that contribute to the early detection of any mechanical failure that prevents the total loss of the gas turbine in operation. To achieve the objectives set out in this research, techniques and tools with a systemic and systematic approach are used, which will allow the characterization and interpretation of images of gas turbine blades.

Thermo Mechanical Fatigue Testing of GTD 111 Superalloy for Use in Gas Turbine Blades

2015 ◽  
Vol 830-831 ◽  
pp. 211-214 ◽  
Author(s):  
Brijesh Patel ◽  
Kalpit P. Kaurase ◽  
Anil M. Bisen
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Fatigue Testing ◽  
Material Selection ◽  
Turbine Blades ◽  
Operating Conditions ◽  
Limiting Factors ◽  
Test Results ◽  
Gas Turbine Blades ◽  
Mechanical Fatigue

Design of Turbo machinery is complex and efficiency is directly related to material performance, material selection is of prime importance. Temperature limitations are the most crucial limiting factors to gas turbine efficiencies. This paper presents the life of GTD 111 applied to gas turbine blade based on LCF and TMF test results. The LCF tests were conducted under various strain ranges based on gas turbine operating conditions. In addition, IP (in-phase) and OP (out of-phase) TMF tests were conducted under various strain ranges. The paper will focus light on above issues and each plays an important role within the Gas Turbine Material literature and ultimately influences on planning and development practices. It is expected that this comprehensive contribution will be very beneficial to everyone involved or interested in Gas Turbines.

The High Temperature Turbo-jet Engine

1956 ◽  
Vol 60 (549) ◽  
pp. 563-589 ◽  
Author(s):  
D. G. Ainley
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Axial Flow ◽  
Jet Engine ◽  
Gas Turbine Blades ◽  
Turbine Design ◽  
The University ◽  
Transfer Problems

The 985th Lecture to be given before the Society, “ The High Temperature Turbo-jet Engine ” by D. G. Ainley, B.Sc, A.M.I.Mech.E., A.F.R.Ae.S., was given at the Institution of Civil Engineers, Great George St., London, S.W.I on 15th March 1956, with Mr. N. E. Rowe, C.B.E., D.I.C., F.C.G.I., F.I.A.S., F.R.Ae.S., in the Chair. Introducing the Lecturer, Mr. Rowe said that Mr. Ainley had been working on gas turbines since 1943 when he joined the gas turbine division of the Royal Aircraft Establishment. He transferred to Power Jets Ltd. and later to the National Gas Turbine Establishment. His early work was associated with the development of axial flow compressors, contraction design and so on; he then transferred to turbine design, became head of the section dealing with turbine and heat transfer problems and for the past five or six years had been chiefly engaged on the cooling of gas turbine blades. Mr. Ainley graduated from the University of London, Queen Mary College, with first class honours. In 1953 he was awarded the George Stephenson Research Prize by the Institution of Mechanical Engineers.

Operating Results With Gas Turbines of Large Output

1964 ◽  
Vol 86 (1) ◽  
pp. 29-49 ◽  
Author(s):  
H. Pfenninger
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Ash Content ◽  
Liquid Fuels ◽  
Gas Turbine Blades ◽  
Gaseous Fuels ◽  
Fuel Oils ◽  
Dust Composition

Operational figures of some Brown Boveri gas-turbine installations classed according to the fuel burned: oil, blast furnace gas, natural gas. Corrosion and contamination of gas-turbine blades, laboratory and pilot tests, general considerations, fuel oils obtainable, their ash content and composition, and their suitability for use in gas turbines. Effect of the ash content and ash composition of liquid fuels, and of the dust content and dust composition of gaseous fuels on the life of the blading material. Drop in output and efficiency with time. Reduction of the rate of contamination of the blades by additives in the fuel. Experience with natural gas-fired gas turbines. Plant maintenance costs.

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