• Title/Summary/Keyword: Corrosion detection

Search Result 163, Processing Time 0.022 seconds

Development of Eddy Current Test Probe for Profilometry Inspection of Tube (원형튜브 단면형상검사용 와전류탐촉자 개발)

  • Lee, H.J.;Nam, M.W.;Lee, C.H.
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.17 no.4
    • /
    • pp.262-269
    • /
    • 1997
  • An eddy current probe ($8{\times}1$ multiple-element, surface scan) was successfully designed and fabricated at the KEPRI using the impedance equivalent circuit theory. The probe is intended for the detection of circumferential deformations (cross-section view) of the heat exchanger tubing that can occur due to corrosion, erosion, and denting. Optimum design parameters providing the highest sensitivity and signal-to-noise ratio, such as the coil dimensions, electrical characteristics, and test frequencies, were determined based on initial laboratory experiments conducted on the test specimen (SS304 tubing: OD : 9.68mm, wall-thickness : 0.47mm) containing artificial flaws (e.g., dents and corroded surface on tube OD) using the available Zetec-made probe. Using this parameters, a new probe was made and tested on an unknown specimen. The result indicated that the new probe is capable of detecting the circumferential deformation with the error of ${\pm}0.2%$ (0.022mm) of the tube O.D.

  • PDF

Structural Performance Investigation for the Reinforced Concrete Frames Deteriorated by the Reinforcement Corrosion (철근부식에 의한 철근콘크리트골조의 구조성능분석)

  • Choi, Se-Woon
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.28 no.5
    • /
    • pp.563-570
    • /
    • 2015
  • The existing research on the damage detection method for building structures has considered the damages from the excessive loadings such as the earthquake. However, the structural performance of building structures could be reduced due to the deterioration based on the chloride, carbonation during the long-term time. Thus, to effectively manage the healthiness of structures, the deterioration influences on the structures should be checked. In this study, the corrosion of rebars by the chloride is considered as the deterioration factor. To consider the structural performance reduction of the corroded rebars, the yield strength, cross-sectional area, rupture strain of rebars and the compressive strength of cover concrete based on the corrosion level are estimated. These properties of rebars and cover concrete are used for the procedure to evaluate the structural performance reduction of structural member level and the building level. The moment-curvature analysis is performed to evaluate the structural performance reduction of structural member level. Also, the eigenvalue analysis and the pushover analysis are performed to investigate the natural period and mode shape and the strength and deformation performance of buildings, respectively.

Pipeline Defects Detection Using MFL Signals and Self Quotient Image (자기 누설 신호와 SQI를 이용한 배관 결함 검출)

  • Kim, Min-Ho;Rho, Yong-Woo;Choi, Doo-Hyun
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.30 no.4
    • /
    • pp.311-316
    • /
    • 2010
  • Defects positioning of underground gas pipelines using MFL(magnetic flux leakage) inspection which is one of non-destructive evaluation techniques is proposed in this paper. MFL signals acquired from MFL PIG(pipeline inspection gauge) have nonlinearity and distortion caused by various external disturbances. SQI(self quotient image), a compensation technique for nonlinearity and distortion of MFL signal, is used to correct positioning of pipeline defects. Through the experiments using artificial defects carved in the KOGAS pipeline simulation facility, it is found that the performance of proposed defect detection is greatly improved compared to that of the conventional DCT(discrete cosine transform) coefficients based detection.

Recent Development in Ultrasonic Guided Waves for Aircraft and Composite Materials

  • Rose, Joseph L.
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.29 no.6
    • /
    • pp.525-533
    • /
    • 2009
  • Emphasis in the paper is placed on describing guided wave successes and challenges for applications in aircraft and composite materials inspection. Guided wave imaging methods discussed includes line of sight, tomography, guided wave C-scan, phased array, and ultrasonic vibration methods. Applications outlined encircles lap splice, bonded repair patch, fuselage corrosion, water loaded structures, delamination, and ice detection and de-icing of various structures.

Review of Radio Frequency Identification and Wireless Technology for Structural Health Monitoring

  • Dhital, Dipesh;Chia, Chen Ciang;Lee, Jung-Ryul;Park, Chan-Yik
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.30 no.3
    • /
    • pp.244-256
    • /
    • 2010
  • Radio frequency identification(RFID) combined with wireless technology has good potential for structural health monitoring(SHM). We describe several advantages of RFID and wireless technologies for SHM, and review SHM examples with working principles, design and technical details for damage detection, heat exposure monitoring, force/strain sensing, and corrosion detection in concrete, steel, carbon fiber reinforced polymer(CFRP), and other materials. Various sensors combined with wireless communication are also discussed. These methodologies can be readily developed, implemented, and customized. There are some technical difficulties, but solutions are being addressed. Lastly, a surface acoustic wave-based RFID system is presented, and possible future trends of SHM based on RFID and wireless technology are presented.

Application of Laser-based Ultrasonic Technique for Evaluation of Corrosion and Defects in Pipeline (배관부 부식 및 결함 평가를 위한 레이저 유도 초음파 적용 기술)

  • Choi, Sang-Woo;Lee, Joon-Hyun;Cho, Youn-Ho
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.25 no.2
    • /
    • pp.95-102
    • /
    • 2005
  • There are many tube and pipeline in nuclear power plant under high temperature and high pressure. Erosion and corrosion defects were expected on these tube and pipe-line by environmental and mechanical factors. These erosion and corrosion defects ran be evaluated by ultrasonic technique. In these study, Scanning Laser Source(SLS) technique was applied to detect defect and construct image. This technique also makes detection possible on rough and curved surfaces such as tube and pipe-line by scanning. Conventional ultrasonic scanning technique requires immersion of specimen or water jet for transferring ultrasonic wave between transducer and specimen. However, this SLS technique does not need contacting and couplant to generate surface wave and to get flaw images. Therefore, this SLS technique has several advantages, for complicated production inspection, non-contact, remote from specimen, and high resolution. In this study, SLS images were obtained with various conditions of generation laser ultrasound and receiving in order to enhance detectability of flaws on the tube. Stress corrosion cracks were produced on tube and images of stress corrosion cracks were constructed by using SLS technique.

Characteristics of OCP of Reinforced Concrete Using Socket-type Electrodes during Periodic Salt Damage Test (주기적 염해 시험에 따른 소켓 타입 전극을 활용한 철근 콘크리트의 OCP 특성)

  • Lee, Sang-Seok;Kwon, Seung-Jun
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.25 no.4
    • /
    • pp.28-36
    • /
    • 2021
  • It is known that buried rebars inside concrete structures are protected from corrosion due to passive layer. It is very important to delay the timing of corrosion or evaluate a detection of corrosion initiation for the purpose of cost-beneficiary service life of a structure. In this study, corrosion monitoring was performed on concrete specimens considering 3 levels of cover depth(60 mm, 45 mm, and 30 mm), W/C(water to cement) ratio(40.0%, 50.0%, and 60.0%) and chloride concentration(0.0%, 3.5%, and 7.0%). OCP(Open Circuit Potential) was measured using agar-based socket type sensors. The OCP measurement showed the consistent behavior where the potential was reduced in wet conditions and it was partially recovered in dry conditions. In the case of 30 mm of cover depth for most W/C ratio cases, the lowest OCP value was measured and rapid OCP recovery was evaluated in increasing cover depth from 30 mm to 45 mm, since cover depth was an effective protection against chloride ion ingress. As the chloride concentration increased, the effect on the cover depth tended to be more dominant than the that of W/C ratio. After additional monitoring and physical evaluation of chloride concentration after specimen dismantling, the proposed system can be improved with increasing reliability of the corrosion monitoring.

Assessment of Pipe Wall Loss Using Guided Wave Testing (유도초음파기술을 이용한 배관 감육 평가)

  • Joo, Kyung-Mun;Jin, Seuk-Hong;Moon, Yong-Sig
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.30 no.4
    • /
    • pp.295-301
    • /
    • 2010
  • Flow accelerated corrosion(FAC) of carbon steel pipes in nuclear power plants has been known as one of the major degradation mechanisms. It could have bad influence on the plant reliability and safety. Also detection of FAC is a significant cost to the nuclear power plant because of the need to remove and replace insulation. Recently, the interest of the guided wave testing(GWT) has grown because it allows long range inspection without removing insulation of the pipe except at the probe position. If GWT can be applied to detection of FAC damages, it will can significantly reduce the cost for the inspection of the pipes. The objective of this study was to determine the capability of GWT to identify location of FAC damages. In this paper, three kinds of techniques were used to measure the amplitude ratio between the first and the second welds at the elbow area of mock-ups that contain real FAC damages. As a result, optimal inspection technique and minimum detectability to detect FAC damages drew a conclusion.

Advantages and disadvantages of renewable energy-oil-environmental pollution-from the point of view of nanoscience

  • Shunzheng Jia;Xiuhong Niu;Fangting Jia;Tayebeh Mahmoudi
    • Advances in concrete construction
    • /
    • v.16 no.1
    • /
    • pp.69-78
    • /
    • 2023
  • This investigation delves into the adverse repercussions stemming from the impact of arsenic on steel pipes concealed within soil designated for rice cultivation. Simultaneously, the study aims to ascertain effective techniques for detecting arsenic in the soil and to provide strategies for mitigating the corrosion of steel pipes. The realm of nanotechnology presents promising avenues for addressing the intricate intersection of renewable energy, oil, and environmental pollution from a novel perspective. Nanostructured materials, characterized by distinct chemical and physical attributes, unveil novel pathways for pioneering materials that exert a substantial impact across diverse realms of food production, storage, packaging, and quality control. Within the scope of the food industry, the scope of nanotechnology encompasses processes, storage methodologies, packaging paradigms, and safeguards to ensure the safety of consumables. Of particular note, silver nanoparticles, in addition to their commendable antibacterial efficacy, boast anti-fungal and anti-inflammatory prowess, environmental compatibility, minimal irritability and allergenicity, resilience to microbial antagonism, thermal stability, and robustness. Confronting the pressing issue of arsenic contamination within both environmental settings and the food supply is of paramount importance to preserve public health and ecological equilibrium. In response, this study introduces detection kits predicated upon silver nanoparticles, providing an expeditious and economically feasible avenue for identifying arsenic concentrations ranging from 0.5 to 3 ppm within rice. Subsequent quantification employs Hydride Atomic Absorption Spectroscopy (HG-AAS), which features a detection threshold of 0.05 ㎍/l. A salient advantage inherent in the HG-AAS methodology lies in its capacity to segregate analytes from the sample matrix, thereby significantly reducing instances of spectral interference. Importantly, the presence of arsenic in the soil beneath rice cultivation establishes a causative link to steel pipe corrosion, with potential consequences extending to food contamination-an intricate facet embedded within the broader tapestry of renewable energy, oil, and environmental pollution.