Post Mortem of a Feedwater Heater With Drains Cooler Failures

2015 ◽  
Author(s):  
Eric Svensson ◽  
D. Chad Halcomb
Keyword(s):  
High Pressure ◽  
Failure Mechanisms ◽  
Post Mortem ◽  
Fossil Plant ◽  
Feed Pump ◽  
Steel Tubes ◽  
Identical Construction ◽  
Outline Drawing ◽  
Station Unit ◽  
Causes Of Failure

The Paradise Generation Station Unit 3 is a supercritical fossil plant with a 1,078 MW rated capacity. The #3B feedwater heater (FWH) is a two-zone (condensing and subcooling) horizontal FWH and is the second of four high pressure (HP) FWHs after the boiler feed pump in the “B” string, one of two HP FWH strings (See Figure A2 at the end of this paper for an outline drawing of the heater. The heater has 1447 SA-556-C2 Carbon Steel tubes, 3/4” OD × 0.085 min wall. The heater was built in late 2006/early 2007 and was installed in summer 2007. After just a few years of operation, the #3B FWH experienced several failures at the entrance to the drain cooler (DC) zone. The #3A FWH, of identical construction and built and installed at the same time, did not show the same level of damage. In order to determine the failure mechanisms involved, a post-mortem of the heater was performed. This paper shall discuss the post-mortem inspection conducted as well as the suspected and confirmed causes of failure in the heater.

The Epidemiology of Revision Total Knee Arthroplasty

2021 ◽  
Author(s):  
John M. Tarazi ◽  
Zhongming Chen ◽  
Giles R. Scuderi ◽  
Michael A. Mont
Keyword(s):  
Total Knee Arthroplasty ◽  
Aseptic Loosening ◽  
Knee Arthroplasty ◽  
Polyethylene Wear ◽  
Failure Mechanisms ◽  
Surgical Techniques ◽  
Index Procedure ◽  
Total Knee ◽  
Modern Era ◽  
Causes Of Failure

AbstractWith an expected increase in total knee arthroplasty (TKA) procedures, revision TKA (rTKA) procedures continue to be a burden on the United States health care system. The evolution of surgical techniques and prosthetic designs has, however, provided a paradigm shift in the etiology of failure mechanisms of TKA. This review can shed light on the current reasons for revision, which may lead to insights on how to improve outcomes and lower future revision risks. We will primarily focus on the epidemiology of rTKA in the present time, but we will also review this in the context of various time periods to see how the field has evolved. We will review rTKAs: 1) prior to 1997; 2) between 1997 and 2000; 3) between 2000 and 2012; and 3) in the modern era since 2012. We will further subdivide each of the sections into reasons for early (first 2 years after index procedure) versus late revisions (greater than 2 years after index procedure). In doing so, it was determined that prior to 1997, the most prevalent causes of failure were infection, patella failure, polyethylene wear, and aseptic loosening. After a major shift of failure mechanisms was described by Sharkey et al, polyethylene wear and aseptic loosening became the leading causes for revision. However, with the improved manufacturing technology and implant design, polyethylene wear was replaced with aseptic loosening and infection as the leading causes of failure between 2000 and 2012. Since that time, in the modern era of TKA, mechanical loosening and infection have taken over the most prevalent causes for failure. Hopefully, with continued developments in component design and surgical techniques, as well as increased focus on infection reduction methods, the amount of rTKA procedures will decline.

Technical Challenges of Retubing the E´lectricite´ de France (EDF) Belleville Unit 2

2011 ◽  
Author(s):  
Merwin W. Jones ◽  
Kim M. Massey ◽  
David Voisin
Keyword(s):  
Leak Test ◽  
Brass Alloy ◽  
Steel Tubes ◽  
Laser Alignment ◽  
Alignment System ◽  
Leak Testing ◽  
Nuclear Station ◽  
Surface Condenser ◽  
Rolling Torque ◽  
Station Unit

This paper describes the numerous challenges involved in the partial retubing of the Belleville Nuclear Station Unit 2 steam surface condenser using 64,242 tubes. Specific challenges of the project included retubing with both duplex stainless steel tubes and with brass alloy tubes, analyzing the risk of flow induced tube vibration and designing a staking system to prevent such vibration, and, replacement of six tubesheets. The tubesheet stresses were analyzed using a beam strip analysis and ANSYS, and new tubesheets were reverse engineered from original drawings. Tubesheets were aligned to the support plate holes using a newly developed laser alignment system. Prior to the retubing, extensive mockup tests were performed to optimize the rolling torque, and to determine rolling parameters that limit the work-hardening of the brass tubes. Testing also included leak testing the mockup joints with a small pressure vessel and then performing a helium leak test of the pressurized tube joints. Tests were performed with both smooth and serrated holes.

Toward a Science of Failure Analysis: A Narrative Review

2021 ◽  
Vol 45 (1) ◽  
pp. 223-252
Author(s):  
Claire Allen-Platt ◽  
Clara-Christina Gerstner ◽  
Robert Boruch ◽  
Alan Ruby
Keyword(s):  
Educational Program ◽  
Large Scale ◽  
Systematic Approach ◽  
Controlled Trial ◽  
Failure Mechanisms ◽  
Educational Interventions ◽  
Randomized Controlled ◽  
Cumulative Knowledge ◽  
K 12 ◽  
Causes Of Failure

When a researcher tests an educational program, product, or policy in a randomized controlled trial and detects a significant effect on an outcome, the intervention is usually classified as something that “works.” When expected effects are not found, there is seldom an orderly and transparent analysis of plausible reasons why. Accumulating and learning from possible failure mechanisms is not standard practice in education research, and it is not common to design interventions with causes of failure in mind. This chapter develops Boruch and Ruby’s proposition that the education sciences would benefit from a systematic approach to the study of failure. We review and taxonomize recent reports of large-scale randomized controlled trials in K–12 schooling that yielded at least one null or negative major outcome, including the nature of the event and reasons (if provided) for why it occurred. Our purpose is to introduce a broad framework for thinking about educational interventions that do not produce expected effects and seed a cumulative knowledge base on when, how, and why interventions do not reach expectations. The reasons why an individual intervention fails to elicit an outcome are not straightforward, but themes emerge when researchers’ reports are synthesized.

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