Shaft crack detection in a steam turbine isma past editions. Fouling of steam turbine blades and vanes is a common problem. Geothermal steam turbine retrofit for performance improvement and life extension. Jun 11, 2011 steam turbine basic accessories and questionsanswers. They are subject to cracking by a variety of failure mechanisms. Turbine is an engine that converts energy of fluid into mechanical.
Maintenance and repair of steam turbines disassembling, maintenance, assembling of hp, ip, lp turbines inspection of all parts and reachable area of rotor by ndtut, pt, mt, replica, rt tests. Damage assessment and refurbishment of steam turbine. Third party inspection for steam turbine overspeed test. Using the latest repair technologies, you can expect fast and reliable solutions either on site or using our extensive factory network. Parts and functions of steam turbine rotor stem chest casing over speed trip system governor system steam chest and the casing.
Methods of to maintaining turbine discs prone to cracks in bucket attachment dovetails are disclosed. Expansion occurs through a series of fixed blades nozzles and also moving blades. The matching of surfaces for leak proof steam and oil joints are ensured. According to the invention, to detect incipient cracks in the rotor of a fluid powered turbine, very small cracks are made to be active and to manifest themselves as larger cracks which are normally open during parts of each revolution of the rotor during a period following a transient perturbation of the rotor. Despite their complexity, steam turbine blades and rotor develop cracks for a handful of reasons at multiple locations airfoil, root, tenon, snubber, cover band, disk rim etc. The design criteria for the steam turbine must include optimum materials, detailed stress and lowcycle fatigue lcf analysis, verification testing, fracture mechanics analysis and advanced nondestructive examination nde testing. Rare radial steam turbine rejuvenated power engineering. The facility has leadingedge equipment and repair techniques with proven expertise on multiple frame gas turbine hot gas path and combustion components. Both the ends are supported on independent pedestals. Failure analysis of a steam turbine rotor sciencedirect. With over eighty years of experience we support and assist our customers with advanced engineering, production and quality expertise. Corrosion cracking of rotor steels of steam turbines springerlink. The cracks located in the blade root tang was due to corrosion fatigue.
Dye penetrant inspection technique of turbine rotating. Siemens power generation service coordinates the resources, processes and technology to deliver maintenance and repair with minimal downtime through the global service network. Us8240042b2 methods of maintaining turbine discs to. Geothermal steam turbine rotor repair after stress corrosion cracking sulzer received a 55 mw geothermal steam turbine rotor from a customer in the philippines for repair. When turbine is in service, superheated steam temperature above 540 degree celsius is admitted into the turbine.
Maintenance partners repair proposal offered a solution in which the steam turbine would be running within 6 months. Causes and resolution of stress corrosion cracking in steam turbines. Onsite repairs and grinding of rotor shaft, alternator shaft and turbine shaft is executed in place which eliminates downtime associated with the disassembly. Conversely, if the symptoms of a shaft crack are not detected, its propagation can cause. Figure 2 shows an example of a singleshaft gas turbine rotor. For low and moderate inlet steam pressure up to 120 bar, a single shell. Ges industrial steam turbine repair services have developed an array of proven repair techniques for all parts.
Online cleaning is possible that doesnt require dismantling although the results are not guaranteed. Failure analysis investigations were carried out on a failed interfering part of journal bearing related to turbine of a steam power. Bertilson, stress corrosion cracking of steam turbine. The sixth stage disk of an integral steam turbine rotor of a customer in india developed cracks in the root sections of the blade attachments. The steam turbines are widely used in power generation, refineries and petrochemical industries. With 9,000 industrial steam turbines installed in the region, europe is a key core services market for ge. This work presents dynamic analysis of a cracked rotor system in a steam turbine unit a typical rotor system with multiple rotors, multiple supports, and oscillating loads, and the vibrational features of the cracked rotor system with comparisons to typical features in monitored vibration data. Factory repairs maintenance, repair and parts solutions. An increasing number of lowpressure steam turbines especially at supercritical fossil unitshave experienced stress corrosion cracking in the blade attachment region of their lowpressure rotors. Third party inspection for steam turbine rotor balance. Take advantage of gas turbines chemical processing. Ra power solutions is a service provider that facilitates power plant operations like turbine shaft repair, rotor shaft grinding, rotor shaft repair all over the world to minimize the downtime. Failure analysis of a steam turbine rotor request pdf. These bearings must be accurately aligned to maintain the close clearances between the shaft and the shaft seals, and between the rotor and the casing.
The analysis of the data allowed drawing some conclusions. Steam turbine blade cracking often suggests the need for an upgraded blade design. Below are excerpts from a case study, successful online and offline cleaning of steam. An investigation into failure analysis of interfering part. Cracked steam turbine rotor repaired and reinstalled with 8% improvement on performance. In this article, we will discuss steam turbine basic parts.
Failure of a steam turbine rotor due to circumferential crack. Thus a steam turbine could be viewed as a complex series of windmilllike arrangements, all assembled on the same shaft. Steam turbine interview questions part 01 objectivebooks. Oct, 2017 in this video we learn turbine diagram,shaft,wheel,bucket. The rotors of steam turbines belong to the extremely loaded parts of turbo generators. Failure of a steam turbine rotor due to circumferential crack growth influenced by temperature and steady torsion article in engineering failure analysis 66 april 2016 with 47 reads. This is a 214 mw steam turbine rotor which is unusual because it has the high pressure, intermediate pressure, and low pressure sections all on the same rotor. Lprimlife for rotors with bladeattachment cracking suitable for use with all rotor designs, lprimlife developed on behalf of epri, is a software code to assess the life of steam turbine rotors with bladeattachment cracking. The failure of the first stage blade in a steam turbine of 55 mw was investigated. Every start, stop and load change decreases the net lcf life of a steam turbine. Ashutosh vengurlekar exxonmobil research and engineering, singapore. In april 2009, the steam turbine was overhauled again.
When a damaged steam turbine rotor needed to be repaired. Turbine shaft repair, rotor shaft grinding ra power solutions. Apr 23, 20 steam turbines manufacturer, industrial steam turbines, condensing steam turbine in india ctmi, one of the leading steam turbine manufacturers, situated in hoskote, 25 kms from bangalore, ctmi has, within a decade, rolled out a number of turbines up to 30 mw. A range of low alloy steels, commonly used in the construction of steam turbines, has been tested for susceptibility to stress corrosion cracking scc in pure condensing steam and pure water. The objective of this paper is to evaluate postulated cracks in a power plant steam turbine and to rank the cracks to prioritize inspection. Like the blades, the steam turbine rotors are highly stressed components. In this case, 2 turbine disks of a steam turbine are built up by welding. What provisions in the layout of a combinedcycle should be considered. For example if a blade of turbine cracks, operators. Failure of a steam turbine rotor due to circumferential. Maximum steam flow through a turbine, th 655 outlet steam pressure of hp turbine, for design flow, mpa 2. Causes and resolution of stress corrosion cracking in steam. And when they occur the result is catastrophic with the complete destruction of the unit and the total loss of generating capacity. They can be cracks, failure, or damage of turbine parts and equipment, and can cause damage to or failure of the steam turbine.
Bievenue ge company schenectady, new york introduction ge turbine designs have evolved over a period of some 90 years, during which over 3,000 units were produced, with the objective of achieving the best. It has been shown that when tested for prolonged periods, the steels will initiate cracks in steam only at very high stresses. The following paper presents the results of the analysis of failure causes of the rotor shaft of a steam turbine with the power of 6,43 mw, which occurred after approximately one year. New welding material for repairing turbines sulzer. Maintenance partners welding robot is used for tig, mig and mag welding of rotors and shafts. To ensure that the steam turbine would operate again, maintenance partners had to completely redesign, rebuild and realign major components. Understanding that proximity, speed and quality services are all equally important to the success of your business, we have developed a dedicated steam power europe industrial organization made up of customer relations, leadership, product line and services teams with expertise specific. These include many specialist repairs for parts such as blade failure, diaphragms, glands, valve components, rotors, and casing. Steam turbine retrofitting for the life extension of power plants. Specify combinedcycle steam turbines rotors for daily. The equipment had been well maintained and the service history was available to the maintenance engineers. No indication of contact with other parts was observed by visual.
To recommend a permanent fix first requires an understanding of how and why unexpected fatigue or rupture occurred. In a steam turbine, the heat energy of steam is converted into kinetic energy by allowing it to expand through a series of nozzles and this kinetic energy of steam is then imparted to the turbine blades mounted on a shaft free to rotate to drive this prime mover. Through optimal application of technology and proven expertise, stork turbo blading is unmatched in its ability to produce the blades in. The steam turbines principle is that the steam energy is converted into mechanical energy by expansion through the turbine. Properly functioning steam turbine valves and governors are critical to the successful operation of your power plant.
The rotor behavior, confirmed high probability of the shaft crack presence on the steam turbine rotor. In the second part, weight functions with five and six terms are derived separately at the surface and the deepest points of semi elliptical crack to determine the stress intensity factors. Burghard, cracking of low pressure turbine rotor disks in us. The strength and reliability of steam turbine elements in operation is. Answer it is important to consider the use of a bypass stack that will permit operating the gas turbogenerator in case of a forced outage on the hrsg or steam turbogenerator. Erc turbine is 2 shock road condition blade root dimension is within design. The thermal expansion clearances between the stator and rotor parts are checked and recorded. The steam turbine rotors showed abnormal thermal and load sensitivity with the abnormal rotor response. As wellknown experts in the repair of steam turbines, sulzer was called in to.
However, delivery, installation and commissioning a new steam turbine was estimated to take up to 2 years. Results and discussion the various parts of the steam turbine evaluated were both the compressor and generator rotor, turbine blades, the diffuser, the exhaust hoods, the compressor casings, the. What is the nature of rotor surface cracks in steam turbines. Stress corrosion of steam turbine disc and rotor steels. Causes and resolution of stress corrosion cracking in. In the wake of the catastrophic failure of a lowpressure lp turbine disk at the hinkley point nuclear station in 1969, considerable research and development has been devoted to the problem of stress corrosion cracking scc in steam turbine rotors. The rotor is turned by steam impinging against attached vanes or blades on which it exerts a force in the tangential direction. Analysis of the inspection showed that the rh rotor had helical linear cracks on all of the steam inlets, both rotors had excessive steam seal clearances and both of the rotor couplings would need. In these utilities, rotor is among the most critical and highly stressful components. Repairing lowpressure rotors with cracked blade attachments. Crack of a first stage blade in a steam turbine sciencedirect.
Steam turbine components that operate under conditions of high temperatures andor stresses develop cracks. Our facility has leadingedge equipment and repair techniques with proven expertise on multiple frame gas turbine hot gas path and combustion components. Steam turbine rotor cracks mrmyers mechanical 6 jun 10 23. Oxford instrument, which can determine the elements including the carbon content. Oct 29, 2018 in the first case, the row six disk of an integral steam turbine rotor developed cracks in the root sections of the blades. A steam turbine is a device that extracts thermal energy from pressurized steam and uses it to do mechanical energy on a rotating output shaft. The blade was made of 174 ph stainless steel and has been used for 12 years before failure. Cracks are appeared in aged steam turbines as a result of these tensions and operational conditions including corrosive environment and high temperature. A steam turbine consists of a rotor resting on bearings and enclosed in a cylindrical casing. Rather than wait for at least a year for a new rotor from the oem, the plant opted for a repair that took only 16 weeks. Upgrading of material specifications to be more durable. The bearing clearances, centering and alignment values are ensured before the turbine is released for mechanical run test mrt.
A complete and thorough cleaning would require stoppage and opening up the turbine, which may mean shutting down a profitable process. Us8240042b2 methods of maintaining turbine discs to avert. The casing shape and construction details depend on whether it is a high pressure hp or low pressure lp casings. When a turbine rotor comes from operation to stop, there can be a thermal gradient from upper to lower casing, with. In the first case, the row six disk of an integral steam turbine rotor developed cracks in the root sections of the blades. The turbine blade in a steam turbine has an important role to convert the kinetic. No evidence of an external factor related to steam quality was found. The use of the exhaust heat from a gas turbine improves the overall thermal efficiency. Case study geothermal steam turbine rotor repair after. The rotor was received with stage 3 and stage 4 at the turbine side in unbladed condition. When a damaged steam turbine rotor needed to be repaired, a power generation plant in indonesia turned to sulzer.
The rotors of steam turbines belong to the extremely loaded parts of turbo generators due to various mechanical and thermal influences during their operation. Slip between rotor groove and blade was possible as the vibratory forces exceeded contact force on. Steam turbine blade reverse engineering, upgrade, and. The object of this study was the rotor of a 60 mw steam turbine with a 3000 runmin top speed, and 480 c inlet steam temperature. The turbine has an operating speed of 9000 rpm, and the steam inlet temperature is 400 c 750 f. Maximum crack depth, allowed outage duration, spare parts and repair cost are the key factors for deciding on which suitable actions to be taken. Steam turbine basic parts mechanical engineering site. For many large steam turbines, shaft lift oil systems are utilized to lift the shaft in their journal bearings during starting and to keep the shaft lubricated during coast down of the turbine rotor after steam to the turbine is shut off. Steam turbine critical crack evaluation and ranking cracks to prioritize inspection g. Motors, drives fast repair needed for a power plant steam turbine the repair of a steam turbine, which had a cracked rotor, required some innovative and quick thinking to ensure a quick repair time for a power plant in the philippines.
Follow the process of reversing engineering a failed blade to produce a more reliable and efficient design. The design is a double flow steam turbine type with 5 stages on each side. Parts and functions of steam turbine power plant tutorials. Steam turbine critical crack evaluation and ranking cracks. Steam turbines are one of the most highly used machines in steam power plants to generate electricity. It should be noted that if occurring of fretting fatigue for inner bearing parts leads to rotor vibration, superimposing of fretting and rotor effects enhance the damaging intensity, continuously. Full rotor reblade complete reengineering of the 6th row turbine blades.
How to repair and reinstall a cracked steam turbine rotor. When required by the contract or purchase order, rotor shaft assembly with the necessary half keys is subjected to a dynamic balance check and is witnessed by third party inspector. Steam turbine is device where kinetic energy heat converted into mechanical energy in shape of rotation. Steam turbine interview questions part 03 objectivebooks. Protection of the structural elements of the circulation part of steam turbines. Steam turbine rotor vibration that results in premature failure of blades and other components is one of the most serious problems in power plant operations. In one embodiment, wherein a turbine disc comprises a plurality of bucket attachment dovetail regions, one or more of the bucket attachment dovetail regions comprises a cooling slot, and each cooling slot comprises edges and adjacent surfaces, a method comprises inspecting the one or more of. Awaiting the outcome of the inspection, our client considered ordering a new steam turbine. Third party inspection for steam turbine procedure. Pdf crack of a first stage blade in a steam turbine. Oct 29, 2014 the ability of the aircompressor rotor and stator blades and assemblies to operate in the variablespeed range is important, particularly for singleshaft gas turbines, where the aircompressor shaft is directly coupled to the turbine shaft and drivenequipment rotor assemblies. This is part 1 out of three of the mk2 micro tesla building series.
The tests carried out during residuallife assessment attempt to detect these cracks, so. Nov 25, 2014 turbine rotor as the steam turbine operates under high temperature and speeds high, the material that makes them rotary axis must be homogeneous and pure of impurities that cause cracks under pressure and high temperature as the material must be of high hardness and conducting laboratory tests including examination charpy hardness to make. Load demand, financial pressures and aging steam turbine generators have created the need to extend longevity and reliability. Older steam turbines are prone to stress corrosion cracking of the turbine blades, disks and other components.
The turbine had an operating speed of 9,900 rpm and the steam inlet temperature was 400 c 750 f. In cogeneration, electric power is produced, but part of the steam from the hrsg or from extraction from the steam turbine is used for process heat, hence the term cogenerationthe simultaneous production of electric power and process heat steam. Toshiba manufactures and supplies all forms of valve components, including valve stems, seats, and bushings. Parts and functions of steam turbine are rotor stem, chest casing, over speed trip system, governor system which major equipment in turbines.
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