C219 Velocity field characteristics at pipe-wall thinning position induced by Flow-Accelerated Corrosion

2010 ◽  
Vol 2010.15 (0) ◽  
pp. 367-368
Author(s):  
Masashi Tatematsu ◽  
Sheng Feng ◽  
Shingo Furuya ◽  
Masaya Kondou ◽  
Yoshiyuki Tsuji
Keyword(s):  
Velocity Field ◽  
Pipe Wall ◽  
Accelerated Corrosion ◽  
Wall Thinning ◽  
Flow Accelerated Corrosion

Effects of Flow Accelerated Corrosion on Piping Steady-State Vibration Evaluations

2003 ◽  
Author(s):  
Brian J. Voll
Keyword(s):  
Steady State ◽  
Nuclear Power ◽  
Power Plants ◽  
Pipe Wall ◽  
Vibration Monitoring ◽  
Accelerated Corrosion ◽  
Monitoring Programs ◽  
Wall Thinning ◽  
Piping Systems ◽  
Flow Accelerated Corrosion

Piping steady-state vibration monitoring programs were implemented during preoperational testing and initial plant startup at most nuclear power plants. Evaluations of piping steady-state vibrations are also performed as piping and component failures attributable to excessive vibration are detected or other potential vibration problems are detected during plant operation. Additionally, as a result of increased flow rates in some piping systems due to extended power uprate (EPU) programs at several plants, new piping steady-state vibration monitoring programs are in various stages of implementation. As plants have aged, pipe wall thinning resulting from flow accelerated corrosion (FAC) has become a recognized industry problem and programs have been established to detect, evaluate and monitor pipe wall thinning. Typically, the piping vibration monitoring and FAC programs have existed separately without interaction. Thus, the potential impact of wall thinning due to FAC on piping vibration evaluations may not be recognized. The potential effects of wall thinning due to FAC on piping vibration evaluations are reviewed. Piping susceptible to FAC and piping susceptible to significant steady-state vibrations, based on industry experience, are identified and compared. Possible methods for establishing links between the FAC and vibration monitoring programs and for accounting for the effects of FAC on both historical and future piping vibration evaluations are discussed.

Studies on Flow and Pipe Wall Thinning and the Reduction in the Downstream of Orifice Nozzle

2011 ◽  
Author(s):  
Toshihiko Shakouchi ◽  
Takayuki Suzuki ◽  
Hideki Yuya ◽  
Masaki Naruse ◽  
Koichi Tsujimoto ◽  
...  
Keyword(s):  
Cavitation Erosion ◽  
Pipe Wall ◽  
Liquid Droplet ◽  
Piping System ◽  
Droplet Impingement ◽  
Accelerated Corrosion ◽  
Wall Thinning ◽  
System 1 ◽  
Flow Accelerated Corrosion ◽  
Droplet Impingement Erosion

In a piping system of power plant, pipe wall thinning by Flow Accelerated Corrosion, FAC, Liquid Droplet Impingement Erosion, LDI, and Cavitation Erosion, C/E, are very serious problems because they give a damage and lead to the destructtion of the piping system[1]–[6]. In this study, the pipe wall thinning by FAC in the downstream of orifice nozzle, flow meter, is examined. Namely, the characteristics of FAC, generation mechanism, and prediction of the thinning and the reduction are made clear by experimental analysis. As a results, it was made clear that (1) the thinning is occurred mainly according to the size of the pressure fluctuation p′ on the pipe wall and the thinning can be estimated by it, and (2) the suppression of p′ can be realized by replacing the orifice to a taper shaped one having an angle to the upstream.

Numerical Evaluation of Wall Thinning Profile in Separation and Union Pipe due to Flow Accelerated Corrosion

2014 ◽  
Author(s):  
Shun Watanabe ◽  
Kimitoshi Yoneda
Keyword(s):  
Wall Thickness ◽  
Power Plants ◽  
Pipe Wall ◽  
Branch Pipe ◽  
Residual Lifetime ◽  
Accelerated Corrosion ◽  
Geometry Factor ◽  
T Tube ◽  
Wall Thinning ◽  
Flow Accelerated Corrosion

Flow Accelerated Corrosion (FAC) is a pipe wall thinning phenomenon to be monitored and managed in power plants with high priority. In Japan, its management has been conducted with conservative evaluation of thinning rate and residual lifetime of the piping based on wall thickness measurements. However, noticeable case of the wall thinning occurred at separation and union pipe. In such pipe system, it is a problem to manage a section beneath reinforcing plate of T-tube pipe and a crotch of T-joint pipe; wall thickness measurement with high accuracy is difficult to conduct in the region by using ordinary ultrasonic testing devices. In this study, numerical analysis for separation and union parts of T-tube and T-joint pipes was conducted, and wall thinning profile by FAC was evaluated by calculating mass transfer coefficient and geometry factor. Based on these results, applicable wall thinning management for T-tube and T-joint pipes was considered. In the case of union flow from main and branch pipe, the wall thinning profile of T-tube showed the tendency of increase at main pipe like semielliptical region. On the other hand, noticeable profile appeared at crotch in T-joint although it was found that geometry factor of T-joint in this flow pattern was half the value of T-tube. An alternative evaluation method to previous one might be needed for such semielliptical region in T-tube and crotch in T-joint.

Iatan Desuperheater Pipe Failure Caused by FAC: September 28, 2007

2010 ◽  
Author(s):  
Chong Chiu ◽  
Lance B. Gockel
Keyword(s):  
Wall Thickness ◽  
Pipe Wall ◽  
Preliminary Evaluation ◽  
Pipe Failure ◽  
Accelerated Corrosion ◽  
Wall Thinning ◽  
Plant Personnel ◽  
Serious Injury ◽  
Flow Accelerated Corrosion ◽  
Flow Blockage

At approximately 11:40 AM on May 9, 2007, Iatan Unit 1 experienced a catastrophic rupture of a 4 inch superheater (SH) attemperator spray line after nearly 27 years of commercial operations. At the time of the rupture, several plant personnel were in the immediate vicinity performing maintenance on a plugged coal feeder. Plant operators immediately initiated a plant shutdown. This incident resulted in two fatalities and one serious injury. Subsequent examination of the ruptured line indicated significant pipe wall thinning had occurred, leading to the sudden failure of the pipe pressure boundary and the pipe rupture event. The preliminary evaluation of the failed pipe determined that flow accelerated corrosion (FAC) was the likely failure mechanism. To prevent this and similar events, the PII team recommends the following actions be taken to identify other potential areas which may have similar characteristics to the failed pipe: 1. Employ the EPRI method CHECKWORKS (as has been implemented) to identify the susceptible areas. 2. Supplement the EPRI model with connected flow modeling techniques to identify additional inspection areas. 3. If the measured wall thickness is less than 30% of the minimum allowable wall thickness, replace or repair the pipe immediately. 4. If the measured wall thickness is less than the minimum allowable wall thickness (as specified by the B31.1 code), but no less than 30% of the minimum allowable, perform a safety risk assessment. If the risk is determined acceptable, replace or repair the pipe at the next planned plant outage with temporary compensatory actions (such as caution tags, leak flow blockage facilities, etc.). 5. Identify and replace all throttled gate valves and replace them as soon as practical. Until these valves are replaced, utilize NDE techniques to monitor the pipe wall thinning downstream of the valves and replace pipe based on the above criteria in 3 and 4.

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