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Proceedings Papers
AM-EPRI2004, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Fourth International Conference, 919-929, October 25–28, 2004,
... steel. Results are presented for tubes and pipes cast with a variety of surface conditions. In addition, detailed results are provided on the effects of alloying elements on creep and oxidation resistance. bending boiler tubes creep rupture strength ferritic stainless steel headers...
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A new 12%Cr steel, VM12, has been developed with the combined strength and oxidation resistance characteristics desired for high-temperature applications. The steel increases chromium content by around 0.2% to improve oxidation properties while alloying with other elements such as cobalt, tungsten, and boron to meet a range of requirements, including extending fatigue life. The steel is designed to have the same creep strength as T/P92 but with better oxidation resistance due to the higher chromium content. It has about a 0.2% increase in mechanical properties compared to T/P92 steel. Results are presented for tubes and pipes cast with a variety of surface conditions. In addition, detailed results are provided on the effects of alloying elements on creep and oxidation resistance.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 1025-1037, October 22–25, 2013,
... current designs. Inconel alloy 740H (UNS N07740) is a new nickel- based alloy that serves as a candidate for steam header pipe and super-heater tubing in coal-fired boilers. Alloy 740H has been shown to be capable of withstanding the extreme operating conditions of an advanced ultra-super-critical (AUSC...
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The use of high-nickel superalloys has greatly increased among many industries. This is especially the case for advanced coal-fired boilers, where the latest high temperature designs will require materials capable of withstanding much higher operating temperatures and pressures than current designs. Inconel alloy 740H (UNS N07740) is a new nickel- based alloy that serves as a candidate for steam header pipe and super-heater tubing in coal-fired boilers. Alloy 740H has been shown to be capable of withstanding the extreme operating conditions of an advanced ultra-super-critical (AUSC) boiler, which is the latest boiler design, currently under development. As with all high nickel alloys, welding of alloy 740H can be very challenging, even to an experienced welder. Weldability challenges are compounded when considering that the alloy may be used in steam headers, where critical, thick-section and stub-to-header weld joints are present. This paper is intended to describe the proper procedures developed over years of study that will allow for ASME code quality welds in alloy 740H with matching composition filler metals.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 265-275, October 22–25, 2013,
... Abstract Inconel alloy 740H is designated for boiler sueprheater/reheater tubes and main steam/header pipes application of advanced ultra-supercritical (A-USC) power plant at operating temperatures above 750°C. Microstructure evolution and precipitates stability in the samples of alloy 740H...
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Inconel alloy 740H is designated for boiler sueprheater/reheater tubes and main steam/header pipes application of advanced ultra-supercritical (A-USC) power plant at operating temperatures above 750°C. Microstructure evolution and precipitates stability in the samples of alloy 740H after creep-rupture test at 750°C, 800°C and 850°C were characterized in this paper by scanning electron microscopy, transmission electron microscopy and chemical phase analysis in details. The phase compositions of alloy 740H were also calculated by thermodynamic calculation. The research results indicate that the microstructure of this alloy keeps good thermal stability during creep-rupture test at 750°C, 800°C and 850°C. The precipitates are MC, M 23 C 6 and γ′ during creep-rupture test. The temperature of creep test has an important effect on the growth rate of γ′ phase. No harmful and brittle σ phase was found and also no γ′ to η transformation happened during creep. Thermodynamic calculations reveal almost all the major phases and their stable temperatures, fractions and compositions in the alloy. The calculated results of phase compositions are consistent with the results of chemical phase analysis. In brief, except of coarsening of γ′, Inconel alloy 740H maintains the very good structure stability at temperatures between 750°C and 850°C.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 215-229, October 22–25, 2013,
... 20.4 Figure 8. As-extruded 740H steam header pipe measuring 14.9 inches (378mm) x 3.47 inches (88mm) x 34.5 feet (10.5m). Figure 9. Charpy impact results (10mm x 10mm samples) for solution annealed and aged pipe produced from ingot 1-A, after exposure at the indicated temperatures and times. 221 Figure...
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Inconel alloy 740H was specifically developed for use in coal-fired AUSC boilers. This alloy displays a unique combination of steam and coal-ash corrosion resistance, microstructure stability, creep strength and heavy section weldability. During the past two years Special Metals and Wyman-Gordon have undertaken an intense effort to demonstrate their capability to manufacture full-size boiler components, characterize their properties and simulate field assembly welds. This work was performed according to the requirements of ASME Boiler Code Case 2702 that was recently issued. This paper covers manufacturing of tube and pipe products and property characterization including recent data on the effect of long time exposure on impact toughness of base and weld metal. New data will also be reported on coal ash corrosion of base metal and weld metal. An overview of welding studies focused on integrity of circumferential pipe joints and a discussion of remaining technical issues will be presented.
Proceedings Papers
AM-EPRI2010, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Sixth International Conference, 916-932, August 31–September 3, 2010,
...-forged it at 5:1 and 12:1 reductions, to assess feasibility of the alloy as a wrought advanced stainless steel for potential use as steam headers and piping for A-USC power plant applications. The hot-forged alloy has a recrystallized grain structure 6-9 times finer than the as-cast dendritic structure...
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Advanced Ultra-supercritical (A-USC) steam power-plant technology is being developed for better efficiency and lower emissions at 700°C and above, but is based mainly on Ni-based alloys. The ability to include lower-cost alloys with appropriate high-temperature performance should have substantial technological and economic benefits. CF8C-Plus is a cast austenitic stainless steel recently developed for other applications at 600-900°C, which has creep-strength comparable to many solid-solution Ni-based alloys. EPRI and Carpenter Technology produced a 400 lb heat of CF8C-Plus steel and hot-forged it at 5:1 and 12:1 reductions, to assess feasibility of the alloy as a wrought advanced stainless steel for potential use as steam headers and piping for A-USC power plant applications. The hot-forged alloy has a recrystallized grain structure 6-9 times finer than the as-cast dendritic structure, resulting in better strength and impact resistance at room-temperature, and about 20% higher yield-strength (YS) at 760°C, and similar or better ductility compared to the as-cast material. The initial creep-rupture testing at 700-800°C for up to 2000h also indicates similar or better rupture resistance and better creep-ductility for wrought compared to cast material. The next steps needed to test performance of the wrought austenitic stainless steel for extruded headers and piping are discussed.
Proceedings Papers
AM-EPRI2024, Advances in Materials, Manufacturing, and Repair for Power Plants: Proceedings from the Tenth International Conference, 418-428, October 15–18, 2024,
... fabricated headers is finally described. The findings in this paper serve as a guideline for FAC risk assessment, FAC investigation and mitigation, and service in compact heat recovery steam generators. 418 INTRODUCTION Flow Accelerated Corrosion or FAC Flow Accelerated Corrosion or FAC is a corrosion...
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Recently, single-phase flow accelerated corrosion (FAC) has been found extensively in Thailand, especially in single shaft combined cycle power plant heat recovery steam generators, the design of which are compact and cannot be easily accessed for service. This takes at least one week for repairing and costs at least half a million dollar per shutdown. In this paper, the investigation of the single-phase FAC in a high-pressure economizer of a combined cycle power plant is demonstrated. Water chemical parameters such as pH and dissolved oxygen are reviewed, the process simulation of the power plant is performed to capture risk areas for the FAC. A computational fluid dynamics study of the flow is done to understand the flow behavior in the damaged tubes next to an inlet header. Some modifications such as flow distributor installation and tube sleeve installation were performed for short-term solutions. Moreover, new economizer headers are designed with low alloy material to mitigate the problem. The installation process of the newly fabricated headers is finally described. The findings in this paper serve as a guideline for FAC risk assessment, FAC investigation and mitigation, and service in compact heat recovery steam generators.
Proceedings Papers
AM-EPRI2024, Advances in Materials, Manufacturing, and Repair for Power Plants: Proceedings from the Tenth International Conference, 284-295, October 15–18, 2024,
... project scope included fabrication of full-scale superheater / reheater components and subassemblies (including tubes and headers), furnace membrane walls, steam turbine forged rotor, steam turbine nozzle carrier casting, and high temperature steam transfer piping. Materials of construction included...
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A United States-based consortium has successfully completed the Advanced Ultra-Supercritical Component Test (A-USC ComTest) project, building upon a 15-year materials development effort for coal-fired power plants operating at steam temperatures up to 760°C. The $27 million project, primarily funded by the U.S. Department of Energy and Ohio Coal Development Office between 2015 and 2023, focused on validating the manufacture of commercial-scale components for an 800 megawatt power plant operating at 760°C and 238 bar steam conditions. The project scope encompassed fabrication of full-scale components including superheater/reheater assemblies, furnace membrane walls, steam turbine components, and high-temperature transfer piping, utilizing nickel-based alloys such as Inconel 740H and Haynes 282 for high-temperature sections. Additionally, the team conducted testing to secure ASME Code Stamp approval for nickel-based alloy pressure relief valves. This comprehensive effort successfully established technical readiness for commercial-scale A-USC demonstration plants while developing a U.S.-based supply chain and providing more accurate cost estimates for future installations.
Proceedings Papers
AM-EPRI2019, 2019 Joint EPRI – 123HiMAT International Conference on Advances in High-Temperature Materials, 1476-1486, October 21–24, 2019,
... (3500 psia).The A-USC ComTest project scope includes fabrication of full scale superheater / reheater components and subassemblies (including tubes and headers), furnace membrane walls, steam turbine forged rotor, steam turbine nozzle carrier casting, and high temperature steam transfer piping...
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Following the successful completion of a 15-year effort to develop and test materials that would allow advanced ultra-supercritical (A-USC) coal-fired power plants to be operated at steam temperatures up to 760°C, a United States-based consortium has been working on a project (AUSC ComTest) to help achieve technical readiness to allow the construction of a commercial scale A-USC demonstration power plant. Among the goals of the ComTest project are to validate that components made from the advanced alloys can be designed and fabricated to perform under A-USC conditions, to accelerate the development of a U.S.-based supply chain for key A-USC components, and to decrease the uncertainty for cost estimates of future commercial-scale A-USC power plants. This project is intended to bring A-USC technology to the commercial scale demonstration level of readiness by completing the manufacturing R&D of A-USC components by fabricating commercial scale nickel-based alloy components and sub-assemblies that would be needed in a coal fired power plant of approximately 800 megawatts (MWe) generation capacity operating at a steam temperature of 760°C (1400°F) and steam pressure of at least 238 bar (3500 psia).The A-USC ComTest project scope includes fabrication of full scale superheater / reheater components and subassemblies (including tubes and headers), furnace membrane walls, steam turbine forged rotor, steam turbine nozzle carrier casting, and high temperature steam transfer piping. Materials of construction include Inconel 740H and Haynes 282 alloys for the high temperature sections. The project team will also conduct testing and seek to obtain ASME Code Stamp approval for nickel-based alloy pressure relief valve designs that would be used in A-USC power plants up to approximately 800 MWe size. The U.S. consortium, principally funded by the U.S. Department of Energy and the Ohio Coal Development Office under a prime contract with the Energy Industries of Ohio, with co-funding from the power industry participants, General Electric, and the Electric Power Research Institute, has completed the detailed engineering phase of the A-USC ComTest project, and is currently engaged in the procurement and fabrication phase of the work. This paper will outline the motivation for the effort, summarize work completed to date, and detail future plans for the remainder of the A-USC ComTest project.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 1006-1015, October 22–25, 2013,
... and reheater headers were designed assuming steam conditions of 35MPa/700ºC/720ºC (main steam 1012 Figure 11: Narrow gap HST butt welding of superheater header pipe of HR6W (OD558.8, WT138) (A) GTAW socket welding (B) GTAW orbital welding (C) SMAW socket welding Figure 12: Stub-header socket welding and stub...
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In recent years continuous and extensive research and development activities have been being done worldwide on 700°C A-USC (Advanced Ultra Super Critical) power plants to achieve higher efficiency and reduce the CO 2 emission. Increasing steam temperature and pressure of such A-USC boilers under consideration require the adoption of Ni based alloys. In the Japanese national project launched in 2008, Ni based alloy HR6W (45Ni-23Cr-7W-Ti, ASME Code Case 2684) is one of the candidate materials for boiler tube and pipe as well as Alloy617, Alloy263 and Alloy740H. The most important issues in A-USC boiler fabrication are the establishment of proper welding process for thick wall components of these alloys and verification of the long term reliability of their weldments. In our previous study, the weldability of HR6W was investigated and the welding process for Ni based thick wall pipe was established with the narrow gap HST (Hot wire Switching TIG) welding procedure originally developed by Babcock-Hitachi K.K. In this paper, creep rupture strengths of HR6W weldment were verified by the long term test up to 60,000 hours for tube and 40,000 hours for pipe. In Japanese national project, narrow gap HST welding process was also applied to the welding test for the other Ni based candidate pipe materials. Furthermore, as the practical A-USC boiler manufacturing trials, header mockup test was conducted and qualified for HR6W.
Proceedings Papers
AM-EPRI2016, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Eighth International Conference, 260-270, October 11–14, 2016,
... OF THE HEADER Fig. 2 shows the drawing of the header and its installation in the test loop. A thick-walled pipe (body) was the basis of the header subjected to the main steam. The component had five bypasses (thin-walled boiler tubes that have been welded with their respective entry and exit openings...
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In the test loop HWT II (High Temperature Materials Test Loop) installed in the fossil power plant Grosskraftwerk (GKM) Mannheim in Germany, thick-walled components made of nickel base alloys were operated up to temperature of 725 °C. The operation mode chosen (creep-fatigue) was to simulate a large number of start-ups and shutdowns with high gradients as expected for future high efficient and flexible power plants and to investigate the damage due to thermal fatigue of the used nickel base alloys. In this paper the damage evolution of a header made of the nickel base alloys Alloy 617 B and Alloy C263, which was a part of HWT II test rig, were investigated using nondestructive and destructive techniques. Furthermore, the damage has been considered and evaluated by using numerical methods. In addition, different lifetime assessment methods of standards and recommendations with focus on creep-fatigue damage were used and evaluated. The different lifetime models are applied to the header and the results were compared to the results of metallographic investigations and damage observations.
Proceedings Papers
AM-EPRI2016, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Eighth International Conference, 161-168, October 11–14, 2016,
... header. The paper gives details of the material selection process, joint design and the verification process used for the joint. austenitic stainless steel coal fired boilers creep strength materials selection pipe transition joints precipitation hardenable nickel superalloys thermal...
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INCONEL 740H has been developed by Special Metals for use in Advanced Ultra Super Critical (A-USC) coal fired boilers. Its creep strength performance is currently amongst the ‘best in class’ of nickel based alloys, to meet the challenge of operating in typical A-USC steam temperatures of 700°C at 35 MPa pressure. Whilst the prime physical property of interest for INCONEL 740H has been creep strength, it exhibits other physical properties worthy of consideration in other applications. It has a thermal expansion co-efficient that lies between typical values for Creep Strength Enhanced Ferritic (CSEF) steels and austenitic stainless steels. This paper describes the validation work in support of the fabrication of a pipe transition joint that uses INCONEL 740H pipe, produced in accordance with ASME Boiler Code Case 2702, as a transition material to join P92 pipe to a 316H stainless steel header. The paper gives details of the material selection process, joint design and the verification process used for the joint.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 190-201, October 22–25, 2013,
... joint and bent part properties, and weld cracking susceptibilities of Ni-based alloys such as HR6W, HR35 and two types of Alloy617 (High B and Low B) pipes were evaluated. Additionally, two types of HR6W header mock-ups and a HR6W tube element mock-up were fabricated. With the exception of Alloy617...
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In order to reduce CO 2 emissions and improve power generation efficiency, a development project involving an advanced USC (A-USC) plant has been carried out in Japan since 2008. Nibased alloys are candidate materials for boiler components with high temperature steam conditions, which are much stronger than conventional heat resistant steel. However, Ni-based alloys have never been applied with respect to the high pressure parts and thick walled components of USC coal-fired power plants. In this study, therefore, fabrication and characteristic properties, such as weldability, the weld joint and bent part properties, and weld cracking susceptibilities of Ni-based alloys such as HR6W, HR35 and two types of Alloy617 (High B and Low B) pipes were evaluated. Additionally, two types of HR6W header mock-ups and a HR6W tube element mock-up were fabricated. With the exception of Alloy617 (High B), the fabrication trials of Ni-based alloy pipes were conducted successfully, and the long-term creep strength of weldments and bends of Ni-based alloy pipes were found to be nearly equivalent to those of base metal. In the case of Alloy617 (High B), hot cracking was observed.
Proceedings Papers
AM-EPRI2016, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Eighth International Conference, 326-335, October 11–14, 2016,
... Abstract This paper reports the performance of HR6W iron-nickel based alloy and 617B nickel based alloy which are the candidate material for high temperature reheater outlet header of advanced secondary reheat ultra-supercritical unit boiler with reheat steam 653 °C, and analysis the applicable...
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This paper reports the performance of HR6W iron-nickel based alloy and 617B nickel based alloy which are the candidate material for high temperature reheater outlet header of advanced secondary reheat ultra-supercritical unit boiler with reheat steam 653 °C, and analysis the applicable temperature range of the material. As a result, HR6W is the appropriate material to manufacture high temperature reheater outlet header of A-USC boiler with parameters 620°C /653°C/653°C.
Proceedings Papers
AM-EPRI2016, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Eighth International Conference, 1-11, October 11–14, 2016,
... superheater, thick-walled cycling header, steam piping, steam turbine (11 MW nominal size) and valves. Current plans call for the components to be subjected to A-USC operating conditions for at least 8,000 hours by September 2020. The U.S. consortium, principally funded by the U.S. Department of Energy...
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Following the successful completion of a 14-year effort to develop and test materials which would allow advanced ultra-supercritical (A-USC) coal-fired power plants to be operated at steam temperatures up to 760°C, a United States-based consortium has started on a project to build an A-USC component test facility, (A-USC ComTest). Among the goals of the facility are to validate that components made from the advanced alloys can perform under A-USC conditions, to accelerate the development of a U.S.-based supply chain for the full complement of A-USC components, and to decrease the uncertainty for cost estimates of future commercial-scale A-USC power plants. The A-USC ComTest facility will include a gas fired superheater, thick-walled cycling header, steam piping, steam turbine (11 MW nominal size) and valves. Current plans call for the components to be subjected to A-USC operating conditions for at least 8,000 hours by September 2020. The U.S. consortium, principally funded by the U.S. Department of Energy and the Ohio Coal Development Office with co-funding from Babcock & Wilcox, General Electric and the Electric Power Research Institute, is currently working on the Front-End Engineering Design phase of the A-USC ComTest project. This paper will outline the motivation for the project, explain the project’s structure and schedule, and provide details on the design of the facility.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 615-626, October 22–25, 2013,
... Abstract Grade 92 steel has been widely applied in the power generation industry for use as steam pipes, headers, tubes, etc. owing to a good combination of creep and corrosion resistance. For the welding of thick section pipes, a multi-pass submerged arc welding process is typically used...
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Grade 92 steel has been widely applied in the power generation industry for use as steam pipes, headers, tubes, etc. owing to a good combination of creep and corrosion resistance. For the welding of thick section pipes, a multi-pass submerged arc welding process is typically used to achieve sufficient toughness in the weld. To relieve the internal stress in the welds and to stabilise their microstructures, a post weld heat treatment (PWHT) is commonly applied. The heat treatment conditions used for the PWHT have a significant effect on both the resulting microstructure and the creep behaviour of the welds. In this study, interrupted creep tests were carried out on two identical Grade 92 welds that had been given PWHTs at two different temperatures: 732°C and 760°C. It was found that the weld with the lower PWHT temperature had a significantly reduced stain rate during the creep test. In addition, microstructural examination of the welds revealed that the primary location of creep damage was in the heat affected zone in the sample with the lower PWHT temperature, whereas it was in the weld metal in the sample with the higher PWHT temperature. To understand the effect of the different PWHT temperatures on the microstructure, initially the microstructures in the head portions of the two creep test bars were compared. This comparison was performed quantitatively using a range of electron/ion microscopy based techniques. It was apparent that in the sample subjected to the higher PWHT temperature, larger Laves phase particles occurred and increased matrix recovery was observed compared with the sample subjected to the lower PWHT temperature.
Proceedings Papers
AM-EPRI2010, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Sixth International Conference, 995-1013, August 31–September 3, 2010,
... boiler efficiencies, there is a need for superior weld metals and joint designs that optimize the economy of modern boilers and reduce reliance on austenitic materials for steam headers and piping. EPRI has developed a new filler metal, EPRI P87, to enhance the performance of DMWs. Previous work has...
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Dissimilar metal welds (DMWs) between ferritic and austenitic materials at elevated temperatures have long posed challenges for boiler manufacturers and operators due to their potential for premature failure. As the industry moves towards higher pressures and temperatures to enhance boiler efficiencies, there is a need for superior weld metals and joint designs that optimize the economy of modern boilers and reduce reliance on austenitic materials for steam headers and piping. EPRI has developed a new filler metal, EPRI P87, to enhance the performance of DMWs. Previous work has detailed the development of EPRI P87 for shielded metal arc welding electrodes, gas-tungsten arc welding fine-wire, and its application in an ultra-supercritical steam boiler by B&W. This study examines the weldability of EPRI P87 consumables through various test methods, including Varestraint testing (both trans and spot), long-term creep testing (approximately 10,000-hour running tests), procedure qualification records for tube-to-tube weldments between traditional/advanced austenitic steels and creep-strength enhanced ferritic steels, and elevated temperature tensile testing. Macroscopic examinations from procedure qualification records using light microscopy confirmed the weldability and absence of cracking across all material combinations. The findings demonstrate that EPRI P87 is a weldable alloy with several advantages for DMW applications and highlight that specific weld joint configurations may necessitate the use of high-temperature tensile data for procedure qualifications.
Proceedings Papers
AM-EPRI2007, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Fifth International Conference, 564-581, October 3–5, 2007,
... on strength, corrosion, creep properties and thermal stability during service are requested for high temperature steels for boilers, steam lines and headers in Ultra Super Critical (USC) Power Plants. Tenaris has accumulated a great experience in the production of C-Mn and Cr-Mo ferritic/martensitic grades...
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The increasing steam parameters in modern high-efficiency fossil fuel power plants demand advanced materials with enhanced creep strength for operation under extreme temperature and pressure conditions. Tenaris has focused on developing ferritic-martensitic and austenitic grades for tube and pipe applications. At TenarisDalmine, efforts on ferritic-martensitic steels include ASTM Grade 23, a low-alloyed alternative to Grade 22 with 1.5% W, offering good weldability, creep resistance up to 580°C, and cost competitiveness. Additionally, ASTM Grade 92, an improved version of Grade 91, provides high creep strength and long-term stability for components like superheaters and headers operating up to 620°C. At TenarisNKKT R&D, austenitic steel development includes TEMPALOY AA-1, an improved 18Cr-8NiNbTi alloy with 3% Cu for enhanced creep and corrosion resistance, and TEMPALOY A-3, a 20Cr-15Ni-Nb-N alloy with superior creep and corrosion properties due to its higher chromium content. This paper details the Tenaris product lineup, manufacturing processes, and key material properties, including the impact of shot blasting on the steam oxidation resistance of austenitic grades. It also covers ongoing R&D efforts in alloy design, creep testing, data assessment, microstructural analysis, and damage modeling, conducted in collaboration with Centro Sviluppo Materiali.
Proceedings Papers
AM-EPRI2007, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Fifth International Conference, 927-939, October 3–5, 2007,
... Abstract Simplified or reference stress techniques are described and demonstrated for high temperature weld design and life assessment. The objective is the determination of weld life under steady and cyclic loading in boiler headers and piping systems. The analysis deals with the effect...
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Simplified or reference stress techniques are described and demonstrated for high temperature weld design and life assessment. The objective is the determination of weld life under steady and cyclic loading in boiler headers and piping systems. The analysis deals with the effect of cyclic loading, constraint and multiaxiality in a heterogeneous joint. A common thread that runs through most high temperature weld reports and failure analyses is the existence of a relatively creep-weak zone somewhere in the joint. This paper starts with the assumption that the size and creep strength of this zone are known, in addition to parent metal properties. Life prediction requires an efficient analysis technique (such as the reference stress method), which separates the structural and material problems, and does not require complex constitutive models. The approach is illustrated with a simple example of an IN617 main steam girth weld, which could be present in an advanced plant concept with 700°C steam temperature.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 155-166, October 22–25, 2013,
... subjected to thermal cycles and is in operation since November 2012. First results of measurements and numerical calculations for a pipe bend (static loading) as well as pipes and a header (thermal cycles) are presented. Alloy 263 Alloy 617 A-USC plants creep properties low cycle fatigue...
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In several material qualification programs tubes and thick-walled components mainly from Alloy 617 and Alloy 263 were investigated. Results as low cycle fatigue and long term creep behavior of base materials and welds are presented. Numerical models to describe the material behavior have been developed and verified by multiaxial tests. In order to ensure the feasibility of A-USC plants two test loops have been installed in GKM Mannheim – one for tube materials and a new one for thick-walled piping and components. The latter consists of a part with static loading and a part subjected to thermal cycles and is in operation since November 2012. First results of measurements and numerical calculations for a pipe bend (static loading) as well as pipes and a header (thermal cycles) are presented.
Proceedings Papers
AM-EPRI2004, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Fourth International Conference, 837-854, October 25–28, 2004,
... Chemistry Alloy 617, a variant of Inconel 617 that has been dubbed “CCA 617.” The CCA 617 was represented in both thick plate and tubular product forms, but the stainless steel was only available as tubing. Issues that might be encountered in fabricating advanced boiler headers and piping were addressed...
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Construction of boilers that can take advantage of the higher efficiencies offered by thermodynamic cycles operating in the ultrasupercritical range will require materials having elevated temperature properties considerably superior to those of the alloys used in more conventional boilers. While many of the materials currently under consideration for ultrasupercritical boiler applications have seen use in other applications, few have been fully investigated using the product forms and section sizes required by high-temperature, high- pressure steam generators. Before any material can be considered truly applicable for use in these advanced plants, the requirements and effects of boiler industry fabrication processes must be explored in addition to determining the properties of the basic alloys. This need was recognized in a materials evaluation program sponsored by the U.S. Department of Energy and the Ohio Coal Development Office and a portion of this program has been devoted to studying the weldability of candidate ultrasupercritical boiler alloys. This paper describes the results of welding trials involving two of these alloys: Super 304H stainless steel and Controlled Chemistry Alloy 617, a variant of Inconel 617 that has been dubbed “CCA 617.” The CCA 617 was represented in both thick plate and tubular product forms, but the stainless steel was only available as tubing. Issues that might be encountered in fabricating advanced boiler headers and piping were addressed while welding the CCA 617 plate with shielded metal arc and submerged arc processes. Similarly, experience working with tubular product forms of both alloys was gained while making butt joints with an orbital gas tungsten arc process. The paper describes the problems presented, the procedures developed, and the basic characteristics of the welds produced.
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