Life Assessment Of High Temperature Components Research Articles

Residual Creep Life Assessment of High-Temperature Components in Power Industry.

A large percentage of power, petroleum, and chemical plants over the world were in operation for a long duration with the corresponding critical components being used beyond the design life of 30 to 40 years. It is generally more cost-effective to refurbish or modernize the degraded equipment or components, rather than to construct a new plant. Therefore, a reliable plant life extension assessment that can evaluate the critical components is needed. The key element in plant life extension is the residual life assessment technology. However, at present, there is still no general consensus among the industry players on the approach to adopt when performing residual life assessment for such a critical damage mechanism as creep. In this article, a three-level residual life assessment methodology is proposed as a general approach for high-temperature components prone to creep. A detailed validation of the selected guidelines and calculation models is also described. Eventually, an application of the three-level methodology to a real industrial case study is presented.

Prediction of creep crack initiation time based on constraint parameters in specimens with different geometries

Based on two creep constraint parameters (R* and Ac), the constraint-dependent creep crack initiation (CCI) time equations of a Cr–Mo–V steel at 566 °C have been established over a wide range of C* region. The equations are independent on the choice of the reference specimen. Based on the two-parameter (C*-R* and C*-Ac) and the constraint-dependent CCI time equations, the CCI time for the specimens with different geometries and dimensions (with a wide range of constraint levels) has been predicted over a wide range of C* region. The predicted CCI time agrees well with experimental data available and CCI time of finite element simulations based on the creep ductility exhaustion model. The specimen geometry with high constraint strengthens the effect of out-of-plane constraint on the CCI time. The two constraint parameters R* and Ac can give similar CCI time prediction results. The two-parameter approaches with considering constraint effect may be applied in the CCI life assessment of high-temperature components (such as pressure pipes and vessels) under static loads in operating plants.

Effect of constraint on creep crack initiation time in test specimens in ASTM-E1457 standard

The creep crack initiation (CCI) time of six specimen geometries in ASTM E1457 standard has been predicted by using numerical simulations, and the constraint effect on CCI time was analyzed. The results show the specimens with different geometries, size ranges and side-grooves recommended by ASTM-E1457 produce different CCI time data due to different constraint levels. With increasing constraint levels in specimens, the CCI time is reduced. The quantitative correlation formulas of CCI time with creep constraint parameters have been established, and they may be applied in CCI life assessment of high-temperature components for accounting for constraint effect and improving accuracy.

Degradation/Damage Measurement and Life Assessment of High-Temperature Components

Degradation/Damage Measurement and Life Assessment of High-Temperature Components

Degradation/Damage Measurement and Life Assessment of High-Temperature Components

Degradation/Damage Measurement and Life Assessment of High-Temperature Components

Degradation/Damage Measurement and Life Assessment of High-Temperature Components

Degradation/Damage Measurement and Life Assessment of High-Temperature Components

Degradation/ Damage Measurement and Life Assessment of High-Temperature Components

Degradation/ Damage Measurement and Life Assessment of High-Temperature Components

Structural integrity and life extension of high-temperature components

Four different topics for high-temperature components, namely the development of the assessment codes for the structural integrity of high-temperature components, the application of continuous damage mechanics and probabilistic damage mode on the life assessment of high-temperature components, the life extension for high-temperature components and a proposed strategy for remanufacturing of high-temperature components were discussed in this paper. These topics should provide some important insights for the design and re-design of high- temperature components.

Life assessment of high-temperature components of thermal power plants in Japan

Life assessment of high-temperature components in thermal power plants have become an important issue in Japan's power industry. Tokyo Electric Power Company (TEPCO), as well as other utility companies, manufacturers of power generating facilities, and related research organizations, is on the way of establishing systems or methods for life assessment. In this report, taking an example of TEPCO's system, an approach by numerical analysis is described first. Secondly, some examples of non-destructive evaluations which are used or under development in Japan, that is, plastic replication, hardness measurement, electric resistivity measurement, and electrochemical method are described. Finally some activities of Japanese organizations, such as the Iron and Steel Institute of Japan and the Japan Power Engineering and Inspection Corporation, for improving accuracy of these methods are mentioned.

The hypertext-based reference procedure used in an expert system for life assessment of high-temperature components

The paper presents first results of the development of the hypertext-based reference procedure envisaged to be used in an expert system for assessment and management of the remaining life of the high-temperature high-pressurized components of power and process plants. The development is related to the collaboration among a group of European partners on development of expert system applications in the structural assessment and lifetime prediction and management of high-temperature components. The reference procedure is envisaged as a summary of good practice, recommendations, standard regulatory requirements, human expert experience and case histories. The procedure should appear both as a paperwork and as hypertext based software, running on a personal computer. The hypertext software prototype is presented here in more detail.