Repairing Feedwater Heater Tubes Using Explosively Welded and Brazed Sleeves

2005 ◽  
Author(s):  
Thomas J. Muldoon
Keyword(s):  
High Pressure ◽  
High Load ◽  
Operating Period ◽  
Term Operation ◽  
Repair Strategy ◽  
Load Demand ◽  
Operating Margin ◽  
Leak Tightness ◽  
High Level

Failures in either the desuperheating zone or drainscooling zone may occur during the long term operation of high pressure feedwater heaters. When the number of failures gets high, the risk of the loss of generation or availability often requires replacement of a feedwater heater. Often, it is important to maintain a reasonably high level of heater availability while the replacement is planned and procured. It is prudent to minimize the potential for a catastrophic set of tube failures which could result in the potential for a turbine water induction incident or an extended repair outage. In such cases, a repair strategy that includes the use of tube sleeves, also referred to as liners, can provide a high level of leak tightness and can provide the operating margin and reliability to help get a heater through a critical operating period, such as a summer high load demand. Installing a sleeve, which is bonded to the tube on both ends, can provide this level of integrity.

scholarly journals Mapping of affordability levels for photovoltaic-based electricity generation in the solar belt of sub-Saharan Africa, East Asia and South Asia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sándor Szabó ◽  
Irene Pinedo Pascua ◽  
Daniel Puig ◽  
Magda Moner-Girona ◽  
Mario Negre ◽  
...  
Keyword(s):  
East Asia ◽  
South Asia ◽  
Electricity Generation ◽  
Sub Saharan Africa ◽  
Solar Photovoltaic ◽  
Term Operation ◽  
Sub Saharan ◽  
High Level ◽  
Do So

AbstractLack of access to modern forms of energy hampers efforts to reduce poverty. The provision of electricity to off-grid communities is therefore a long-standing developmental goal. Yet, many off-grid electrification projects neglect mid- and long-term operation and maintenance costs. When this is the case, electricity services are unlikely to be affordable to the communities that are the project’s primary target. Here we show that, compared with diesel-powered electricity generation systems, solar photovoltaic systems are more affordable to no less than 36% of the unelectrified populations in East Asia, South Asia, and sub-Saharan Africa. We do so by developing geo-referenced estimates of affordability at a high level of resolution (1 km2). The analysis illustrates the differences in affordability that may be found at the subnational level, which underscores that electrification investments should be informed by subnational data.

Steam Line Integrity Analyses for LTO: Enhancing Credibility With Comprehensive Measurement

2012 ◽  
Author(s):  
Horst Rothenhöfer ◽  
Andreas Manke
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Simulation Models ◽  
Proper Function ◽  
Blow Down ◽  
Term Operation ◽  
High Level ◽  
Comprehensive Measurement

The safety relevant components of nuclear power plant Neckarwestheim 1 — in service since 1976 — have been reviewed and updated for long-term operation (LTO). The actions included hardware retrofits as well as updates of analysis according to the latest state of the scientific and technical knowledge. For large piping such as the steam lines, the established pipes have been retained while the supports have been optimized. All shock absorbers (snubbers) including corresponding inertia have been eliminated resulting in a defined guidance and statically defined displacements. The integrity analyses for the optimized steam lines, including break preclusion, have been validated successfully with comprehensive measurements. The verification has delivered an extra high level of credibility, exceeding the “standard” requirements to achieve fitness for service in long-term operation. Measurement and validation, which are the main focus of this paper, range from monitoring of service loads to the static and dynamic measurements of pressure, local temperatures and displacements during initial start-up after implementation of the design modifications. The proper function of supports has been proved and the quality of the simulation models has been confirmed. Some expected and some unexpected dynamic events have been detected during blow-down tests. It was demonstrated that the amplitudes of all dynamic loads stay within limits. The validation of analyses with comprehensive measurement has been an important proof of quality and delivered the redundancy required for the integrity of a nuclear power plant in service, enhancing the high level of safety even more.

STUDY OF CHARACTERISTICS OF MECHANICAL PROPERTIES OF GAS-DISTRIBUTING STATION PIPES METAL AFTER LONG-TERM OPERATION

2015 ◽  
pp. 86-91
Author(s):  
I. Yu. Bykov ◽  
I. N. Birillo ◽  
P. A. Kuzbozhev
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Internal Pressure ◽  
Dynamic Loading ◽  
Static Loading ◽  
High Speed ◽  
Term Operation ◽  
Loading Effects ◽  
Static And Dynamic Loading

During operation the technological pipelines of gas-distributing station are affected by mechanical static loading resulted from internal pressure of gas in the high pressure pipelines and a dynamic loading from a high-speed stream of gas in low pressure pipelines. A comparison is made of characteristics of mechanical properties of gas-distributing station pipes metal after a long-term operation for the conditions of static and dynamic loading effects.

Fatigue Life Evaluation for the Repair Methods of High Pressure Gas Pipeline

2019 ◽  
Author(s):  
Woo Sik Kim
Keyword(s):  
Finite Element ◽  
High Pressure ◽  
Residual Stresses ◽  
Stress Analysis ◽  
Structural Integrity ◽  
Gas Pipeline ◽  
Optimum Process ◽  
Term Operation ◽  
Steel Sleeve

Abstract High pressure gas pipeline must maintain structural integrity during the design life. To do this, periodic pipeline inspections are carried out, and fitness-for-service assessments are performed on defects found by inspection. Defects that do not meet the evaluation criteria should be repaired and replaced to ensure the integrity of the pipeline structure at the same level as before the defect. High pressure gas pipeline repair method is applied to repair of composite reinforced sleeve and repair of steel sleeve. Although there have been many studies on the short-term structural integrity evaluation of rupture pressure in these repair methods, there is insufficient research to verify whether the long-term operation of the repair pipeline maintains the long-term structural integrity of the repaired pipe. In this study, an optimum process to improve structural integrity was established by investigating effect of the process variables on fatigue lifetime of steel-sleeve repair welds in buried gas pipeline. Residual stresses in the repair welds were derived through sequentially-coupled temperature-stress analysis using ABAQUS, which is a commercial finite element analysis program. In addition, variations of operating stresses were derived by finite element linear elastic stress analysis. Fatigue lifetimes of the steel-sleeve repair welds were evaluated by substituting the derived weld residual stresses and operating stress variations into the structural stress/fracture mechanics approach as input. Appling this method confirms long-term integrity over 200 years in terms of fatigue the abstract here in italics.

scholarly journals Metagenomics Response of Anaerobic Ammonium Oxidation (anammox) Bacteria to Bio-Refractory Humic Substances in Wastewater

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 365 ◽  
Author(s):  
Yabing Meng ◽  
Li-Nan Huang ◽  
Fangang Meng
Keyword(s):  
Humic Substances ◽  
Anammox Bacteria ◽  
Ammonium Oxidation ◽  
Leachate Treatment ◽  
Term Operation ◽  
Comparative Metagenomics ◽  
Electron Shuttles ◽  
One Year ◽  
High Level

Anammox-based processes have been widely applied for the treatment of wastewater (e.g., wastewater irrigation systems and constructed wetland) which consists of bio-refractory humic substances. Nonetheless, the impacts of bio-refractory humic substances on anammox consortia are rarely reported. In the present study, three identical lab-scale anammox reactors (i.e., HS0, HS1 and HS10), two of which were dosed with humic substances at 1 and 10 mg·L−1, respectively, were operated for nearly one year. The long-term operation of the reactors showed that the presence of humic substances in influent had no significant influence on nitrogen removal rates. Despite this, comparative metagenomics showed changes in anammox microbiota structure during the exposure to humic substance; e.g., the relative abundance of Candidatus Kuenenia was lower in HS10 (18.5%) than that in HS0 (22.8%) and HS1 (21.7%). More specifically, a lower level of humic substances (1 mg·L−1) in influent led to an increase of genes responsible for signal transduction, likely due to the role of humic substances as electron shuttles. In contrast, a high level of humic substances (10 mg·L−1) resulted in a slight decrease of functional genes associated with anammox metabolism. This may partially be due to the biodegradation of the humic substances. In addition, the lower dosage of humic substances (1 mg·L−1) also stimulated the abundance of hzs and hdh, which encode two important enzymes in anammox reaction. Overall, this study indicated that the anammox system could work stably over a long period under humic substances, and that the process was feasible for leachate treatment.

Effects of high pressure on the crystallization of carbon fiber reinforced polyetheretherketone (CF/PEEK) laminate composites

1990 ◽  
Vol 48 (4) ◽  
pp. 876-877
Author(s):  
Hong-Ming Lin ◽  
C. H. Liu ◽  
R. F. Lee
Keyword(s):  
High Pressure ◽  
Carbon Fiber ◽  
Sample Surface ◽  
High Yield ◽  
Fiber Reinforced ◽  
Laminate Composites ◽  
Peek Composite ◽  
Continuous Carbon Fiber ◽  
Carbon Fiber Reinforced

Polyetheretherketone (PEEK) is a crystallizable thermoplastic used as composite matrix materials in application which requires high yield stress, high toughness, long term high temperature service, and resistance to solvent and radiation. There have been several reports on the crystallization behavior of neat PEEK and of CF/PEEK composite. Other reports discussed the effects of crystallization on the mechanical properties of PEEK and CF/PEEK composites. However, these reports were all concerned with the crystallization or melting processes at or close to atmospheric pressure. Thus, the effects of high pressure on the crystallization of CF/PEEK will be examined in this study.The continuous carbon fiber reinforced PEEK (CF/PEEK) laminate composite with 68 wt.% of fibers was obtained from Imperial Chemical Industry (ICI). For the high pressure experiments, HIP was used to keep these samples under 1000, 1500 or 2000 atm. Then the samples were slowly cooled from 420 °C to 60 °C in the cooling rate about 1 - 2 degree per minute to induce high pressure crystallization. After the high pressure treatment, the samples were scanned in regular DSC to study the crystallinity and the melting temperature. Following the regular polishing, etching, and gold coating of the sample surface, the scanning electron microscope (SEM) was used to image the microstructure of the crystals. Also the samples about 25mmx5mmx3mm were prepared for the 3-point bending tests.

Vivid Imagers Are Better at Detecting Salient Changes

2006 ◽  
Vol 27 (4) ◽  
pp. 218-228 ◽  
Author(s):  
Paul Rodway ◽  
Karen Gillies ◽  
Astrid Schepman
Keyword(s):  
Individual Differences ◽  
Change Detection ◽  
Visual Imagery ◽  
Detection Task ◽  
Level Of Detail ◽  
Detection Accuracy ◽  
Change Detection Task ◽  
Term Change ◽  
High Level

This study examined whether individual differences in the vividness of visual imagery influenced performance on a novel long-term change detection task. Participants were presented with a sequence of pictures, with each picture and its title displayed for 17  s, and then presented with changed or unchanged versions of those pictures and asked to detect whether the picture had been changed. Cuing the retrieval of the picture's image, by presenting the picture's title before the arrival of the changed picture, facilitated change detection accuracy. This suggests that the retrieval of the picture's representation immunizes it against overwriting by the arrival of the changed picture. The high and low vividness participants did not differ in overall levels of change detection accuracy. However, in replication of Gur and Hilgard (1975) , high vividness participants were significantly more accurate at detecting salient changes to pictures compared to low vividness participants. The results suggest that vivid images are not characterised by a high level of detail and that vivid imagery enhances memory for the salient aspects of a scene but not all of the details of a scene. Possible causes of this difference, and how they may lead to an understanding of individual differences in change detection, are considered.

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