Dissimilar Metal Analysis and Issues

Author(s):  
Robert A. Ainsworth

Detailed analysis of dissimilar metal welds (DMWs) is difficult and the accuracy of the results is often limited by the availability of materials data and knowledge of operating conditions. There are few design or assessment procedures that explicitly take account of the presence of DMWs under high temperature creep and fatigue conditions. One that does is the UK R5 procedure, which provides a simplified assessment approach based on laboratory testing and stress analysis supported by service experience. This paper briefly summarises the R5 approach. Then, more recent work on performance of DMWs operating at high temperature and issues for development of analysis methods is discussed.

2021 ◽  
Author(s):  
Peter James ◽  
David Coon ◽  
Colin Austin ◽  
Nicholas Underwood ◽  
Caroline Meek ◽  
...  

Abstract The “Establishing AMR Structural Integrity Codes and Standards for UK GDA” (EASICS) project was established in 2019 to help support the acceptance of Advanced Modular Reactors, or AMRs, which are typically based on high temperature Generation IV reactors. The EASICS project is aiming to provide guidance on the requirements for codes and standards for the design of AMRs for use in the UK, to ensure that state-of-the art knowledge will be brought to bear on developing the required design and assessment methodologies. The EASICS project started in July 2019 and is looking to complete by December 2021. To support this aim, the work presented in this paper provides an overview of two interacting aspects of the programme. The first is to perform validation tests for high temperature creep-fatigue assessments of a plant relevant component. The second aspect is to use these results, to provide a comparison of internationally recognised approaches for the assessment of high temperature (creep regime) components. This approach will be repeated for two other case scenarios deemed to be plant relevant components. This paper builds upon the initial overview paper presented at the 2020 conference providing an update on progress. One of the cases presented herein, described as the Thin Walled Welded Pipe Test uses specialist testing of a plant relevant component under high temperature loading conditions is underway with some initial results available. The validation testing includes both fatigue tests and creep-fatigue tests on 316H welded thin section tubes. The tubes have been subjected to strain-controlled tension/compression (R-ratio of −1), with some including a displacement controlled dwell. The tests are being conducted at 525°C. An update to the progress of these tests is included herein. To help enhance interaction with the code bodies, and to understand the impact of differences in the approaches, comparative assessments have been performed when adopting R5, ASME Section III Div 5 and RCC-MRx. One comparison will be based around the tests detailed above (tube test). A further assessment comparison will consider the Evasion mock-up tests provided by CEA (sodium based thermal shock tests). The third assessment case is loosely based around a plant relevant assessment within one of the UK Advanced Gas Reactors (AGRs). This paper provides an overview of the results from all these cases using R5, ASME Section III Div 5 and RCC-MRx. The subsequent discussions covers results, differences and potential impact to the codes which will all help to inform a guidance document to support assessing AMRs within a UK regulatory framework.


CORROSION ◽  
1958 ◽  
Vol 14 (12) ◽  
pp. 39-42 ◽  
Author(s):  
A. J. FREEDMAN ◽  
A. DRAVNIEKS

Abstract Since reproduction of refinery operating conditions in the laboratory is difficult, most laboratory testing of refinery corrosion inhibitors has been unreliable. For this reason,, inhibitors for refinery use have been selected mainly on the basis of qualitative field trials. Such tests are expensive and subject to many independent, noncontrollable variables. Frequently, failures of corrosion inhibitors to provide satisfactory protection can be traced to specific environmental factors. Therefore, new laboratory tests for commercial refinery corrosion inhibitors have been developed to simulate closely certain features of actual field conditions. Inhibitors have been evaluated for corrosion protection in light naphtha condensers, distillation towers, special high temperature locations, high velocity service, narrow crevices, and for impingement attack. These test data show conclusively that no single corrosion inhibitor can be expected to provide satisfactory corrosion protection in all refinery locations. Plant results obtained with electrical resistance corrosion probes corroborate the laboratory evaluations. 5.8.1


2020 ◽  
pp. 10-21
Author(s):  
V. G. Babashov ◽  
◽  
N. M. Varrik ◽  

The emergence of new types of space and aviation technology necessitates the development of new types of thermal protection systems capable of operating at high temperature and long operating times. There are several types of thermal protection systems for different operating conditions: active thermal protection systems using forced supply of coolant to the protected surface, passive thermal protection systems using materials with low thermal conductivity without additional heat removal, high-temperature systems, which are simultaneously elements of the bearing structure and provide thermal protection, ablation materials. Heat protection systems in the form of rigid tiles and flexible panels, felt and mats are most common kind of heat protecting systems. This article examines the trends of development of flexible reusable heat protection systems intended for passive protection of aircraft structural structures from overheating.


Alloy Digest ◽  
1964 ◽  
Vol 13 (5) ◽  

Abstract Unitemp-HX is a nickel-base material recommended for high temperature applications. It has outstanding oxidation resistance at high temperatures under most operating conditions, and good high-temperature strength. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness and creep. It also includes information on low and high temperature performance, and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-91. Producer or source: Universal Cyclops Steel Corporation.


Alloy Digest ◽  
1956 ◽  
Vol 5 (7) ◽  

Abstract DOWMETAL HZ32XA is a magnesium-thorium-zinc-zirconium alloy having good high temperature creep resistance, and is recommended for applications at elevated temperatures. It is used in the artificially aged condition (T5). This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance as well as heat treating, machining, and joining. Filing Code: Mg-26. Producer or source: The Dow Chemical Company.


Alloy Digest ◽  
1954 ◽  
Vol 3 (12) ◽  

Abstract HASTELLOY Alloy X is a nickel-chromium-iron-molybdenum alloy recommended for high-temperature applications. It has outstanding oxidation resistance at high temperatures under most operating conditions, and good high-temperature strength. This datasheet provides information on composition, physical properties, and tensile properties as well as creep. It also includes information on forming, heat treating, and machining. Filing Code: Ni-14. Producer or source: Haynes Stellite Company.


Alloy Digest ◽  
1997 ◽  
Vol 46 (4) ◽  

Abstract Remanit 4306 is a low-carbon chromium nickel austenitic stainless steel that is superior in corrosion resistance to type 302 (see Alloy Digest SS-99, revised September 1998). Due to its low carbon content, Remanit 4306 is intergranular corrosion resistant under continuous operating conditions up to 350 C (652 F). This grade is particular suitable for high degrees of cold working and for sequential drawing. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, and joining. Filing Code: SS-679. Producer or source: Thyssen Stahl AG.


2019 ◽  
pp. 43-48
Author(s):  
Ben Nengjun ◽  
Zhou Pengfei ◽  
Oleksandr Labartkava ◽  
Mykhailo Samokhin

This work involves an analysis of high-chromium high-temperature deformable wieldable nickel alloys for use in GTE repair assemblies. It is shown that the alloys EP868 (VZh98) and Haynes 230 can be used in welded assemblies with an operating temperature of 800-1100 °C. The alloys Nimonic 81, Nimonic 91, IN 935, IN 939, and Nicrotan 2100 GT also have a high potential for use in welded assemblies. They are characterized by a combination of good weldability, high-temperature strength, and resistance to scaling. There have been conducted studies on high-temperature salt corrosion of model nickel alloys. They allowed establishing the patterns of the impact of base metal alloying with chromium, aluminum, titanium, cobalt, tungsten, molybdenum, niobium, tantalum and rare earth metals on the critical temperature of the start of salt corrosion Tcor and the alloy mass loss. It has been established that alloys with a moderate concentration (13-16%) of chromium can possess satisfactory hightemperature corrosion resistance (HTC resistance) under the operating conditions of ship GTE. The HTC resistance of CrAl-Ti alloys improves upon reaching the ratio Ti/Al ˃ 1. Meanwhile, the ratio Ti/Al ˂ 1 promotes the formation of corrosion products with low protective properties. The positive effect of tantalum on the HTC resistance of alloys is manifested at higher test temperatures than that of titanium, and the total content of molybdenum and tungsten in alloys is limited by the condition 8Mo2 – 2W2 = 89. The presence of refractory elements stabilizes the strengthening phase and prevents formation of the ɳ-phase. However, their excess promotes formation of the embrittling topologically close packed (TCP) phases and boundary carbides of an unfavorable morphology. Based on the studies of the HTC resistance, there has been identified a class of model high-temperature corrosionresistant nickel alloys with a moderate or high chromium content (30%), Ti/Al ˃ 1, and a balanced content of refractory and rare-earth elements.


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