Search Results for qualifications

The US Advanced Ultra-Supercritical (A-USC) Consortium conducted an extensive program to evaluate available superalloys for use in rotors for steam turbines operating at a nominal temperature of 760 °C (1400 °F). Alloys such as 282, Waspaloy, 740H, 720Li, and 105 were tested in the form of bar supplied from the alloy producers. Ultimately, alloy 282 was down-selected for the turbine rotor based on its combination of creep strength, phase stability, ductility, and fatigue resistance. The next step in development was to produce a full-size rotor forging for testing. A team was established consisting of GE Power (project management and testing), Wyman-Gordon (forging and testing) and Special Metals (melting and billetizing) to pursue the work. A research license to melt the alloy was obtained from Haynes International. The first step of the development was to devise a triple melt (VIM-ESR-VAR) practice to produce 610 mm (24 inch) diameter ingot. Two ingots were made, the first to define the VAR remelting parameters and the second to make the test ingot utilizing optimum conditions. Careful attention was paid to ingot structure to ensure that no solidification segregation occurred. A unique homogenization practice for the alloy was developed by the US Department of Energy (DOE) and National Energy Technology Laboratory (NETL). Billetization was performed on an open die press with three upset and draw stages. This procedure produced an average grain size of ASTM 3. A closed die forging practice was developed based on compressive flow stress data developed by Wyman Gordon Houston for the consortium project. Multiple 18 kg forgings were produced to define the forging parameters that yielded the desired microstructure. The project culminated with a 2.19 metric ton (4830 lb), 1.22 m (48 inch) diameter crack-free pancake forging produced on Wyman Gordon’s 50,000 ton press in Grafton, MA. The forging process produced a disk with an average grain size of ASTM 8 or finer. Forging cut-up, microstructural characterization, and mechanical property testing was performed by GE Power. Fatigue and fracture toughness values of the disk forging exceeded those previously reported for commercially available rolled bar.

For plants with ultra critical steam conditions with live steam temperatures up to 720°C and pressure up to 300 bars optimized materials are required. These are a ferritic-bainitic material (T24) for applications up to 550°C, modified 9 Cr steels (E911 and P92), a new Co-alloyed martensitic 12 Cr steel for usage up to 630°C and Nickel based alloys (Alloy 617) for temperatures above 650°C. Experimental work has been done to create a reliable data base for design and inspection. Special emphasis was put on long term creep characteristics of base material with specific consideration of cross welds, microstructural investigations with regard to optimization of chemical composition and heat treatment and numerical modeling.

SMST is producing Ni alloy Boiler tubes since more than 10 years with application in several test loops and R&D programs. This paper will give an overview about the experience with the common grades A617 as well as C263 plus some additional information on the new developed austenitic material “Power Austenite MoW”.

Components exposed to the highest temperatures and mechanical loading in 700°C power plants are predominantly manufactured from nickel-based alloys, with ongoing material development for boiler and turbine components in this challenging temperature regime. This paper presents comprehensive investigations of various components, including tubing, membrane walls, and thick-walled structures constructed from nickel-based alloys. Qualification programs for boiler components have demonstrated the applicability of Alloy 617, with similar extensive programs and investigations currently underway for Alloy 263 and Alloy 740. Researchers have conducted detailed experiments and investigations to optimize and qualify welding consumables, aiming to transfer critical knowledge directly to component manufacturing processes. Recognizing the complexity of material performance, the study emphasizes the necessity of long-term material qualification, which extends beyond traditional creep behavior assessments to include detailed investigations of deformation capabilities following extended aging periods. These comprehensive evaluations are crucial for ensuring the reliability and performance of advanced high-temperature power plant components under extreme operational conditions.

The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Codes (BPVC) and Code for Pressure Piping have been utilized extensively for the construction and maintenance of plants in the power generation industry. These codes consist of different relevant sections that are applicable to the various pressure retaining components and their service application. This paper presents a comparison of the welding requirements between the various ASME construction codes outside of the qualification requirements within Section IX. Topics of discussion include preheat temperature, interpass temperature, postweld heat treatment, toughness testing, filler material requirements, and use of standard welding procedure specifications. Individual paragraphs and subparagraphs specific to these topics are compared and contrasted to establish their similarities and differences.

The mechanical behavior of a cast form of an advanced austenitic stainless steel, CF8C-Plus, is compared with that of its wrought equivalent in terms of both tensile and creep-rupture properties and estimated allowable stress values for pressurized service at temperatures up to about 850°C. A traditional Larson-Miller parametric model is used to analyze the creep-rupture data and to predict long-term lifetimes for comparison of the two alloy types. The cast CF8C-Plus exhibited lower yield and tensile strengths, but higher creep strength compared to its wrought counterpart. Two welding methods, shielded-metal-arc welding (SMAW) and gas-metal-arc welding, met the weld qualification acceptance criteria in ASME BPVC Section IX for the cast CF8C-Plus. However, for the wrought CF8C-Plus, while SMAW and gas-tungsten-arc welding passed the tensile acceptance criteria, they failed the side bend tests due to lack of fusion or weld metal discontinuities.

This paper explores the development and qualification of a bainitic-martensitic steel grade and its matching welding consumables for power plants operating under ultra-supercritical steam conditions (605/625°C and 300/80 bar). It provides insights into recent developments and offers practical considerations for handling this material (grade T24) from the perspective of both tubular component manufacturers and welding consumable producers. The paper is structured into three main sections: (1) Development and qualification of the T24 steel base material. (2) Development, qualification, and recommendations for welding consumables compatible with T24 steel. (3) Experiences during manufacturing and installation of components using T24 steel, concluding with key takeaways.

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.

This paper presents the CEN WS064 Prospective Group 2, a project involving different European stakeholders from more than 20 organizations with the objective to identify the needs and propose code developments research for the nuclear design and construction code RCC-MRx for innovative reactors with more onerous operational conditions: i) reactor components are generally exposed to higher temperatures; ii) have innovative and more corrosive coolants such as liquid lead or molten salt; iii) materials and components are generally exposed to higher radiation levels than light-water reactors. The main outputs of the CEN WS064 are code evolution proposals and proposals for pre-normative research in support of code evolution. The code evolution is driven by further improving safety and cost reduction. Nuclear Design Codes are robust engineering tools but should incorporate new technologies and research. The paper describes the adopted methodology and the rationale for identifying code evolution needs. Code evolution and research proposals will be discussed. Examples of proposals that will be discussed include: Guideline for design of material/components with innovative coolants, extension of design life to 60 years; qualification of new materials and components with advanced manufacturing. A general requirement is that code evolution and associated material and component qualification and codification need to be significantly accelerated for which new approaches such as AI tools will play an important role.

A significant research and development effort is underway to support the qualification of Alloy 709 as a Class A construction material in the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section III, Division 5, High Temperature Reactors. This initiative includes a comprehensive Alloy 709 code qualification plan aimed at generating extensive material testing data crucial for compiling the code case data package. The data package is essential in establishing material-specific design parameters for Alloy 709 to be used as Section III, Division 5 Class A construction material for fast reactors, molten salt reactors and gas-cooled reactors. An ASME Section III, Division 5 material code case requires the evaluation of mechanical properties from a minimum of three commercial heats, covering anticipated compositional ranges. A key part of the data package involves fatigue and creep-fatigue testing at elevated temperatures, needed for developing the fatigue design curves and the damage envelope of the creep-fatigue interaction diagram (D-diagram). This paper summarizes the strain-controlled fatigue testing on three commercial heats of Alloy 709 at 760 and 816°C with strain ranges between 0.25% and 3%. The fatigue failure data are used to generate a preliminary fatigue design curve. Additionally, the creep-fatigue testing results at 816°C with tensile hold times of 10, 30, and 60 minutes are presented in support of developing the D-diagram for Alloy 709.

Components in ultrasupercritical steam (USC) boilers will operate under significantly more severe conditions than current subcritical and supercritical steam boilers. Existing construction rules for power boilers lack design guidance or criteria to assess the adequacy of designs for USC conditions. A Department of Energy (DOE) project addresses this by evaluating advanced materials under conditions similar to potential USC service environments. The project focuses on six tubing alloys and four thick-section alloys. Testing is underway for pressurized tube bends, notched thick-section bars, fatigue, and thermal shock on thick-section tubing made of materials like CCA617, Alloy 230, and Alloy 740. Further testing is planned for pressurized tubes, dissimilar metal welds, and thick-section weldments. This paper summarizes the status of this initial testing program aimed at enabling USC boiler material qualification.

Investigations on welded joints made from a modified parent material and welding consumables are described. Tubes and pipes with typical dimensions have been welded using different welding processes and consumables (GTAW, SAW, SMAW, modified filler metals). The influence of melting loss and chemical composition of the consumables on the weld performance was studied. Short-term tensile and long-term creep tests on cross weld specimens were carried out in order to evaluate strength. The results obtained so far show that the properties of the welded joints are rather optimistic, it could be assumed that the modified Alloy 617 and the welding consumables used will meet the requirements for use in a plant operated at ultra critical steam conditions with live steam temperatures up to 720°C and pressure up to 300 bar. This allows for first practical applications in test loops of plants. These applications including the Welding Procedure Qualifications are described.

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.

To improve efficiency and flexibility and reduce CO 2 emissions, advanced ultra super critical (AUSC) power plants are under development, worldwide. Material development and its selection are critical to the success of these efforts. In several research and development programs / projects the selection of materials is based on stress rupture, oxidation and corrosion tests. Without doubt, these criteria are important. To improve the operational flexibility of modern power plants the fatigue properties are of increased importance. Furthermore, for a safe operation and integrity issues the knowledge about the crack behavior is essential. Crack initiation and crack growth may be caused by natural flaws or cracks induced by component operation. In order to develop new materials, properties like tensile strength and creep strength are an important part of qualification and subsequent approval by notified bodies. Consequently short term properties as well as time-temperature dependent properties are generated and taken into considerations. In the case of high strength γ'-strengthening nickel-base alloys investigating the creep crack behavior is also strongly recommended. This article shows results of currently investigated nickel-based alloys for newly developed headers, pipes and other high temperature boiler applications and their critical creep crack propagation behavior.

Flux cored wires are worldwide used in power generation industry due to their technical and economic advantages. For welding P91 and P92 flux cored wires with a rutile slag system are available for several years. Results of long-term investigations up to 30.000 h show that specimens of all weld metal meet the requirements of the base material. Following the recent demand of reduced Mn+Ni content the chemical composition of all weld metal has been modified. For P91 a matching flux cored wire with Mn+Ni<1wt% and for P92 with Mn+Ni<1.2wt% is now available. In this paper the mechanical properties of all weld metal and welded joints are being presented. Latest developments in cast materials have shown that the so-called CB2 (GX13CrMoCoVNbNB 10-1-1) enables steam temperatures up to 620°C (1148°F). Therefore a matching flux cored wire with low Ni-content has been developed. Results of welding procedure qualification and first experience of manufacturing industrial components show the successful implementation of this new material grade and welding consumable.

Welding of collector pipes, flat heads, dished ends and connector pipes performed with high temperature and creep-resistant steels most often has been performed using GTAW process combined with MMA processes. Progress in GMAW process and availability of high quality filler materials (solid wires) enables welding of the above connections also using this method. In order to prove its efficiency, this article presents the results of related tests. The range of tests was similar to that applied during the qualification of welding procedure. The investigation also involved microscopic and fractographic examinations and creep tests. The results reveal that welding with GMAW is by no means inferior to a currently applied SMAW method yet the time of the process is shorter by 50%. The article presents the world’s first known positive results in welding of P92 grade steel using GMAW welding method.

Development activities initiated over a decade ago within the COST 522 program and continuing through the COST 536 Action have yielded significant progress in constructing a new generation of steam power plants capable of operating under advanced steam conditions. These innovative plants promise substantially improved thermal efficiency, with steam temperatures reaching up to 620°C (1150°F). Recent successful power plant orders in Europe and the United States stem from critical advancements, including the development, testing, and qualification of 10% Cr steels with enhanced long-term creep properties for high-temperature components such as turbine rotors and valve casings. Extensive in-house development efforts have focused on fabrication, weldability, mechanical integrity, and fracture mechanics evaluations of full-sized forged and cast components. These materials will be implemented in several new coal-fired power plants, notably the Hempstead plant in the USA, which will operate with live steam temperatures of 599°C (1111°F) and reheat steam temperatures of 607°C (1125°F). The improved creep properties enable the construction of casings with reduced wall thicknesses, offering greater thermal flexibility at lower component costs and facilitating welded turbine rotors for high-temperature applications without requiring cooling in the steam inlet region. Looking forward, further efficiency improvements are anticipated through the introduction of nickel alloys in steam turbine and boiler components, with the European AD700 project targeting reheat steam temperatures of 720°C (1328°F) and the US Department of Energy project aiming even higher at 760°C (1400°F). The AD700 project has already demonstrated the technical feasibility of such advanced steam power plants, with engineering tasks progressing toward the construction of a 550 MW demonstration plant, while DOE activities continue to address boiler concerns and focus on rotor welding, mechanical integrity, and steam oxidation resistance.

The Advanced Materials and Manufacturing Technologies (AMMT) program is aiming at the accelerated incorporation of new materials and manufacturing technologies into nuclear-related systems. Complex Ni-based components fabricated by laser powder bed fusion (LPBF) could enable operating temperatures at T > 700°C in aggressive environments such as molten salts or liquid metals. However, available mechanical properties data relevant to material qualification remains limited, in particular for Ni-based alloys routinely fabricated by LPBF such as IN718 (Ni- 19Cr-18Fe-5Nb-3Mo) and Haynes 282 (Ni-20Cr-10Co-8.5Mo-2.1Ti-1.5Al). Creep testing was conducted on LPBF 718 at 600°C and 650°C and on LPBF 282 at 750°C. finding that the creep strength of the two alloys was close to that of wrought counterparts. with lower ductility at rupture. Heat treatments were tailored to the LPBF-specific microstructure to achieve grain recrystallization and form strengthening γ' precipitates for LPBF 282 and γ' and γ" precipitates for LPBF 718. In-situ data generated during printing and ex-situ X-ray computed tomography (XCT) scans were used to correlate the creep properties of LPBF 282 to the material flaw distribution. In- situ data revealed that spatter particles are the potential causes for flaws formation in LPBF 282. with significant variation between rods based on their location on the build plate. XCT scans revealed the formation of a larger number of creep flaws after testing in the specimens with a higher initial flaw density. which led to a lower ductility for the specimen.

This paper reports on the latest in a series of projects aiming at the qualification of new and proven materials in components under a severe service environment. In the initial stages of the project (HWT I & HWT II), a test loop at Unit 6 of the GKM Power Plant in Mannheim was used to study the behavior of components for advanced ultra-supercritical (A-USC) plants made from nickel alloys at 725 °C under both static and fluctuating conditions. Due to recent changes in the operation modes of existing coal-fired power plants, the test loop was modified to continue operating the existing nickel components in the static section while applying thermal cycles in a different temperature range. HR6W pipes and valves were added to the bypass of the static section, and all components in the cyclic section were replaced with P92, P93, and HR6W components. The test loop achieved approximately 9000 hours of operation and around 800 cycles with holding times of 4 and 6 hours. After dismantling the loop, nondestructive and destructive examinations of selected components were conducted. The accompanying testing program includes results from thermal fatigue, fatigue, thermal shock, and long-term creep tests, focusing on the behavior of base materials and welds, particularly for HR6W, P92, P93, and other nickel-based alloys. Additionally, test results on dissimilar welds between martensitic steel P92 and nickel alloys A617 and HR6W are presented. Numerical assessments using standardized and numerical lifetime estimation methods complement the investigations. This paper provides insights into the test loop design and operational challenges, material behavior, and lifetime, including advanced numerical simulations and operational experiences with valves, armatures, piping, and welds.

The efforts of the European Union and Germany in particular to realize the transformation towards a climate-neutral economy over the coming decades have the establishing of a hydrogen economy as a fundamental milestone. This includes production, import, storage, transportation and utilization of great amounts of gaseous hydrogen in existing and new infrastructure. Metallic materials, mainly steels, are the most widely used structural materials in the various components of this supply chain. Therefore, the accelerated use of hydrogen requires the qualification of materials (i.e., ensuring they are hydrogen-ready) to guarantee the sustainable and safe implementation of hydrogen technologies. However, there is currently no easily applicable and standardized method to efficiently determine the impact of gaseous hydrogen on metallic materials. The few existing standards describe procedures that are complex, expensive, and only available to a limited extent globally. This article outlines the key milestones towards standardizing an efficient testing method as part of the TransHyDE flagship project. This new approach enables testing of metallic materials in gaseous hydrogen using tubular specimens. It uses only a fraction of the hydrogen required by the traditional autoclave method, significantly reducing costs associated with technical safety measures. Among the topics to be discussed are the factors influencing the test procedure, including geometrical considerations, surface quality, gas purity and strain rate.