• Title/Summary/Keyword: carbon steel pipe

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Study on the Effects of Flows on the Acceleration of the Grooving Corrosion in the ERW Pipe (ERW강관에서 홈부식의 가속화에 미치는 유동의 영향에 관한 연구)

  • Kim, Jae-Seong;Kim, Yong;Lee, Bo-Young
    • Journal of Welding and Joining
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    • v.26 no.4
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    • pp.85-91
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    • 2008
  • The grooving corrosion is caused mainly by the different microstructures between the matrix and weld which is formed during the rapid heating and cooling cycle in welding. By this localized corrosion reaction of pipes, it evolves economic problems such as the early damage of industrial facilities and pipe lines of apartment, and water pollution. So lots of researches were carried out already about grooving corrosion mechanism of ERW carbon steel pipe but there is seldom study for water hammer happened by fluid phenomenon and corrosion rate by flow velocity. In this study, the analysis based on hydrodynamic and fracture mechanics was carried out. ANSYS, FLUENT and STAR-CD were used for confirmation of flow phenomenon and stress on the pipe. As the results, fatigue failure is able to be happened by water hammer and grooving corrosion rate is increased cause by turbulent. Grooving corrosion is happened on the pipe, then friction loss of fluid is occurred from corroded part. Erosion can be happened enough in corroded region of microscopic size that wear "V" form. Also pipe is able to be damaged by water hammer effects because of corroded region is general acting as a notch effects. Corrosion depth was more than half of total thickness, it can be damaged from water hammer pressure.

Failure Criteria of a 6-Inch Carbon Steel Pipe Elbow According to Deformation Angle Measurement Positions (변형각의 측정 위치에 따른 6인치 탄소강관엘보의 파괴 기준)

  • Yun, Da Woon;Jeon, Bub Gyu;Chang, Sung Jin;Park, Dong Uk;Kim, Sung Wan
    • Journal of the Earthquake Engineering Society of Korea
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    • v.26 no.1
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    • pp.13-22
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    • 2022
  • This study proposes a low-cycle fatigue life derived from measurement points on pipe elbows, which are components that are vulnerable to seismic load in the interface piping systems of nuclear power plants that use seismic isolation systems. In order to quantitatively define limit states regarding leakage, i.e., actual failure caused by low-cycle fatigue, in-plane cyclic loading tests were performed using a sine wave of constant amplitude. The test specimens consisted of SCH40 6-inch carbon steel pipe elbows and straight pipes, and an image processing method was used to measure the nonlinear behavior of the test specimens. The leakage lines caused by low-cycle fatigue and the low-cycle fatigue curves were compared and analyzed using the relationship between the relative deformation angles, which were measured based on each of the measurement points on the straight pipe, and the moment, which was measured at the center of the pipe elbow. Damage indices based on the combination of ductility and dissipation energy at each measurement point were used to quantitatively express the time at which leakage occurs due to through-wall cracking in the pipe elbow.

Application of corrosion inhibitors to water distribution systems

  • Park, Yong-Il;Woo, Dal-Sik;Cho, Young-Tai;Jo, Kwan-Hyung;Nam, Sang-Ho
    • Journal of Environmental Science International
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    • v.11 no.5
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    • pp.411-418
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    • 2002
  • The current study evaluated the disinfection efficiency of free chlorine and chloramine for microorganisms on various pipe materials, such as copper, galvanized steel, carbon steel, and stainless steel. In addition, the effect of internal pipe corrosion and corrosion inhibitors on the bactericidal efficiency was evaluated using a simulated loop. For disinfection with a phosphate corrosion inhibitor, chloramination was found to be more effective than chlorination due to its persistence. Free chlorine disinfection was optimized with a high phosphoric acid concentration, while chloramine disinfection was optimized with a high phosphoric acid or low polyphosphate concentration. In simulated copper and galvanized steel loop tests, chloramination with phosphoric acid was demonstrated to be more effective.

Strain Distribution Measurement for Wall Thinning Defect in Pipe Bends by ESPI (ESPI 를 이용한 곡관 감육 결함부의 변형률 분포 측정)

  • Naseem, Akhter;Kim, Koung-Suk;Jung, Sung-Wook;Park, Jong-Hyun;Choi, Jung-Suk;Jung, Hyun-Chul
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.120-125
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    • 2007
  • Put Abstract text here The strain distribution measurement for wall thinned pipe bends by ESPI is presented. Defect types observed in the steel piping in the nuclear power plants (NPP) are the crack at the weld part and the wall thinning defect in the pipe bends. Especially, the wall thinning defects in the pipe bends due to the flow-accelerated corrosion (FAC) is a main type of defects observed in the carbon steel piping system. ESPI is one of the optical non-destructive testing methods and can measure the stress and the strain distribution of the object subjected by the tensile loading or the internal pressure. In this paper, the strain distribution of the wall thinned pipe bends due to the internal pressure will be measured by ESPI technique and the results are discussed. From the results, the size of the wall thinning defect can also be measured approximately.

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Effect of Cr content on the FAC of pipe material at 150℃ (150℃에서 원전 2차측 배관재료의 Cr함량에 따른 유체가속부식 특성)

  • Park, Tae Jun;Kim, Hong Pyo
    • Corrosion Science and Technology
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    • v.12 no.6
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    • pp.274-279
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    • 2013
  • Flow accelerated corrosion (FAC) of the carbon steel piping in nuclear power plants (NPPs) has been major issue in nuclear industry. During the FAC, a protective oxide layer on carbon steel dissolves into flowing water leading to a thinning of the oxide layer and accelerating corrosion of base material. As a result, severe failures may occur in the piping and equipment of NPPs. Effect of alloying elements on FAC of pipe materials was studied with rotating cylinder FAC test facility at $150^{\circ}C$ and at flow velocity of 4m/s. The facility is equipped with on line monitoring of pH, conductivity, dissolved oxygen(DO) and temperature. Test solution was the demineralized water, and DO concentration was less than 1 ppb. Surface appearance of A 106 Gr. B which is used widely in secondary pipe in NPPs showed orange peel appearance, typical appearance of FAC. The materials with Cr content higher than 0.17wt.% showed pit. The pit is thought to early degradation mode of FAC. The corrosion product within the pit was enriched with Cr, Mo, Cu, Ni and S. But S was not detected in SA336 F22V with 2.25wt.% Cr. The enrichment of Cr and Mo seemed to be related with low, solubility of Cr and Mo compared to Fe. Measured FAC rate was compared with Ducreaux's relationship and showed slightly lower FAC rate than Ducreaux's relationship.

A Study on the Safety of TBP(150A) with Forming Analysis and Strength Test (성형해석 및 강도실험을 통한 분기배관(150A)의 안전성에 관한 연구)

  • Lee, Sung-Ho;Kim, Hei-Song
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.7
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    • pp.610-616
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    • 2008
  • For this study, the forming analyses and body strength tests of TBP were performed on the main pipe size 150A(KS D3507, KS D 3576 10S). The branched pipe sizes utilized were 25A, 32A, 40A, 50A, 65A, 80A, 100A and 125A. A general FEM program, ABAQUS, was used as the forming analyses method of TBP. Using the results, the strength of TBP was then tested in order to determine the safety of TBP when the working pressure was applied. The results indicate that TBP may be safely used in water-based fire protection pipe systems in terms of the strength.

Structural Integrity and Safety Margin Evaluation for Thinned Pipe Component (감육배관의 구조건전성 및 안전여유도 평가 기술)

  • Lee, Sung-Ho;Kim, Tae-Ryong;Kim, Bum-Nyun
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.264-267
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    • 2004
  • Wall thinning of carbon steel pipe components due to Flow-Accelerated Corrosion (FAC) is one of the most serious threats to the integrity of steam cycle piping systems in Nuclear Power Plants (NPP). Since the mid-1990s, secondary side piping systems in Korean NPPs have experienced wall thinning, leakages and ruptures caused by FAC. Korea Electric power Research Institute (KEPRI) and Korea Hydro & Nuclear Power Co., LTD. (KHNP) have conducted a study to develop the methodology for systematic pipe management and established the Korean Thinned Pipe Management Program (TPMP). To effectively maintain the integrity of piping system, FAC engineer should understand the criterions of the structural integrity evaluation and the safety margin assessment for the thinned pipe component. This paper describes the technical items of TPMP, and shows the example of the integrity evaluation and safety margin assessment for three thinned pipe component of a NPP.

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Evaluation of Fracture Resistance Characteristic for Primary Piping System of Ulchin 3,4 Nuclear Power Plants (울진 원자력 발전소 3, 4호기 1차계통 배관소재의 파괴저항특성 평가)

  • 석창성;강병구;김수용;박재실;윤병곤
    • Journal of the Korean Society of Safety
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    • v.14 no.1
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    • pp.25-32
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    • 1999
  • The objective of this paper is to evaluate the fracture resistance characteristics of SA508 CL.1a carbon steel, TP347 stainless steel and their associated welds manufactured for primary coolant system of Ulchin 3,4 nuclear power plants. The effect of various parameters such as pipe size, welding method, chemical composition, crack plane orientation, metallography and fractography on the material properties were discussed. Test results showed that the effect of pipe size on fracture toughness is negligible while the effect of welding method on fracture toughness is significant. In addition, the drop of fracture toughness in the field fabrication weld of TP347 stainless steel is probably due to the large amount of $\sigma$-phase precipitated on the $\delta$-ferrite boundary and the large size dimples.

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