Program 87 - Fossil Materials and Repair
Last Updated: 02-Jun-2016
Today’s fossil power plants are tasked with flexible operations, pushing for maximum output during peak price periods, transitioning to low-load and multi-shift operation, and frequent fuel switching to take advantage of spot market opportunities. These
practices can accelerate material damage in major power block components. New materials are being introduced for replacement of components in aging plants, in the building of higher-efficiency power plants, and in the construction of components with thinner
walls for improved operational flexibility. Regulations on air and water quality have resulted in construction of new pollution control equipment and water management technologies that are more demanding on materials than older systems.
Improved knowledge of materials behavior in such environments allows for accurate prediction of remaining life, proper choice of repair strategies, and optimized material selection, fabrication, and repair. To address these needs, the Electric Power Research
Institute’s (EPRI’s) Fossil Materials and Repair program (Program 87) provides integrated materials selection guidance, repair and welding technologies, and corrosion mitigation methods to improve equipment performance, reliability, and safety. Research is
conducted in all areas of the fossil power plant, including the major power block (boilers, HRSGs, steam turbines, gas turbines, etc.) and the balance of plant.
Safety and availability loss due to failures are two key issues driving R&D on major fossil power plant components, especially in older plants. Improved efficiency and reliability are two reasons for the selection of new materials for retrofit and new-build
projects. EPRI’s Materials and Chemistry programs provide data on critical material degradation mechanisms, conduct materials and chemistry-related R&D for advanced generation technologies, and quantify the benefits of improvements. These programs help utilities
balance the risks and costs of the largest, most costly equipment, and focus on using new technologies to create solutions. Members of the Fossil Materials and Repair program can use the R&D to:
- Increase availability through better understanding of plant materials.
- Minimize -- with the goal to eliminate -- repeat failures and equipment damage, and reduce outage frequency and duration by using improved knowledge of damage mechanisms and tools for life-assessment methods.
- Reduce failures from high- and low-temperature corrosion.
- Obtain in-depth knowledge of advanced ferritic and austenitic alloys and processes used to fabricate and join these alloys.
- Select appropriate weld filler metals and processes for construction and repair.
- Reduce outage time and manage maintenance costs through implementation of innovative repair techniques.
- Maximize component life through improved materials selection guidance and procurement specifications.
Through a continuum of materials and repair guidelines, handbooks, technical projects, webcasts, position papers, and conferences/workshops, the program helps manage and reduce the operating risks associated with material degradation and failure. Projects
develop industry-leading and scientifically based resources to aid in materials property estimates used to determine remaining component life, assess and conduct state-of-the-art repairs, decide on replacement materials, and address costly corrosion and erosion
problems faced in real-world business settings.
Members of the program also benefit from direct access to the technical staff expertise, EPRI laboratories, and a worldwide research network. The program’s mission of research excellence has established EPRI as a leading organization for materials research
for power plants. The program seeks to maximize member value through though internal EPRI collaboration with component-based programs, targeted government-sponsored research, and collaboration with US and international research organizations.
EPRI’s Fossil Materials and Repair program conducts proactive R&D in all aspects of plant materials performance, repair and welding technology development, and corrosion mitigation. It has:
- Provided industry leadership in addressing fabrication, installation, welding, and degradation of creep-strength-enhanced ferritic steels and advanced austenitic stainless steels.
- Developed comprehensive International Steam Boiler and Steam Turbine Metallurgical Guidelines.
- Provided guidance on behavior and remaining life of austenitic stainless steel materials used for superheater and reheater tubing applications.
- Developed welding guidelines for boiler applications and advanced ferritic and austenitic alloys.
- Published a series of metallurgical handbooks (Grade 11, Grade 22, X20, carbon steels, stainless steels, and advanced stainless steels).
- Developed new models for assessing oxide growth and exfoliation.
- Provided innovative solutions and new welding consumables for dissimilar metal weld damage repair and advanced steels.
- Addressed low-temperature corrosion issues around the power plant, including guidance on selecting materials for environmental controls.
- Effectively transferred technology through use of innovative tools and a proactive approach to addressing deficiencies in codes and standards.
The program R&D for 2017 will continue to focus on key issues, including the development of improved specifications through research on metallurgical risk factors; faster weld repairs using innovative techniques; application of small specimen testing for
qualitative and quantitative life assessments in both boilers and turbines; technology transfer for post-weld heat-treatment procedures; materials selection for improved reliability in steam turbine components; and corrosion in the balance of plant. Key specific
efforts are expected to include:
- Development of a metallurgical risk factor for creep strength-enhanced ferritic (CSEF) steels and welds
- Comprehensive guidance on the application of scoop sampling material databases for improved small-specimen remaining-life assessments on a component-specific basis.
- New tools transferring developed post-weld heat treatment guidance
- Improved understanding of damage development in thick-section dissimilar metal welds (DMW)
- Improved filler metal selection for ferritic-to-ferritic dissimilar metal welds (DMWs)
- Innovative repair developments
- Improved guidance on low-temperature corrosion around the entire power plant
- Technology transfer including webcasts, industry position papers, and improvements to codes and standards
Estimated 2017 Program Funding
John Shingledecker, 704-595-2619, email@example.com
Combustion Turbine Weld Repair (Joint P79/87)
When combustion turbine compressor and hot section rotor reach end-of-life, replacement of the rotor disc is generally performed. However, long-lead times may be averted in some instances through weld repair of rotor discs. While this is done routinely
on steam turbines, it has not been performed on gas turbine rotating components and currently there exists no fundamental materials research to support an alternative repair in lieu of replacement.
Dissimilar Metal Welds (DMWs)
Dissimilar metal welds (DMWs) operating at high temperatures and pressures are a challenge for both short- and long-term power plant life management due to complex metallurgical interactions at high termperatures. The industry needs information to better
understand DMW failure modes in order to improve guidance on the welding and fabrication of high reliability DMWs.
FGD Wastewater Materials Selection and Compatibility (Field Testing) - Joint P185/87
Increased emphasis on the treatment and removal of contaminants from power plant wastewater has gained industry attention as new effluent guidelines are now under consideration in the U.S. A key need is to reduce the total volume of water which must be treated
by the power plant, and flue gas desulfurization (FGD) wastewater is the “last stop” for water leaving the plant which needs to be treated. To create less FGD wastewater, the FGD can be “cycled-up” and/or technologies such as membranes can be used to concentrate
These concentrated FGD brines contain high levels of halogens (chlorides, bromides, etc.), low pH values, and other solid and dissolved species. A plethora of materials options to construct treatment systems exist, ranging from alloys such as lower-cost
stainless steels to very expensive nickel-based alloys or titanium. Non-metallic solutions such as coated steels and fiber re-enforced plastic (FRP) can also be used. The industry needs information about the mechanisms of corrosion and criteria for materials
selection in these new environments, which currently are not well understood. EPRI completed a laboratory study as a basis for this materials selection in 2016 and aims to evaluate these same materials in the less controlled real-world field environment to
validate the study conclusions.
Met Risk Grade 91
Long-term creep testing and service experience have clearly shown that composition and processing within the allowed specification for Grade 91 steel can effect long-term creep strength and ductility. The concern over low ductility heats and the potential
for shortened life due to notch weakening effects is a challenge to long-term life management. This project is addressing this challenge through the development of a metallurgical risk factor which will facilitate screening of materials on the basis of composition
and also provide the industry enhanced guidelines for procurement of components (which has already been released in EPRI position papers on chemistry and a publically available specification document).
P87 Application of PWHT Model
Post-weld heat treatment (PWHT) is a critical step in the application of materials in power plants. If a PWHT is conducted incorrectly, serious damage can occur including overtempering and/or anciculary damage to surrounding equipment. This is especially
critical in creep-strength-enhanced ferritic (CSEF steels) because approaching or exceeding the intercritical temperature during PWHT results in significant degradation to creep life and long-term performance. The industry needs to improve PWHT to also improve
long-term performance of CSEF steels in power plants
Service Experience of CSEF Steels in the Asia Pacific Region
The Asia-Pacific region has the fastest growing coal fleet in the world and many of the highest-temperature plants make extensive use of creep strength-enhanced ferritic steels (CSEF). The industry needs to understand the materials challenges, including
early (leading) indicators of what most likely will happen to materials used the most and at highest temperatures. This project seeks to continually engage this region of the world to gain experience with components through industry surveys and assistance
with failure investigations
SOK Low Temp Corrosion
Corrosion costs the electricity industry greater than 2.3B USD/yr. Much of this is corrosion is around the plant in supporting systems which operate at low temperature.
SS SH/RH Damage
Utilities are increasingly using high strength and advanced austenitic stainless steels such as 347H, Super 304H, 347HFG, HR3C, and alike. Failures due to SIPH and relaxation cracking at attachments is not well understood but is critical to proper procurement
of material, specifciations for fabrication, and inspection if failures are found.
Technology Transfer – P87
Even the most impactful R&D results are of little benefit to the industry and the public if they are not delivered in ways that make them easily understood and utilized. EPRI's Fossil Materials and Repair Program (P87) has a comprehensive technology transfer
plan to maximize member engagement, ensure timely delivery of results, and ensure industry leading materials R&D is effectively used in the power industry to advance safe, reliable, affordable, and environmentally responsbile electricity for society.