• 한국가스학회지
• /
• 제15권1호
• /
• pp.15-21
• /
• 2011

본 논문에서는 정량적 위험성 평가 결과 위험경감조치로 제시한 ILI (In-line inspection, 배관내부검사)가 합리적으로 이행가능한지를 판정하기 위해 비용-편익 분석을 실시하였으며, 비용-편익 분석을 통해 ILI의 합리적인 이행시기를 결정하였다. 본 논문에서 편익의 산정은 인간의 생명 가치를 측정하는 VPF (Value of Preventing a Fatality; 사망자를 막는 가치)를 이용하였으며, 국내의 도시가스 고압배관의 위험경감조치에 대한 비용-편익 분석에 적정한 VPF 값은 20억원으로 하였다. 두 개의 사례연구 결과 위험경감조치로 제시된 ILI의 이행시기는 13년을 주기로 2회 (13년 및 25년) 또는 15년이 되는 해 1회 실시하는 것이 가장 합리적임을 알 수 있었다.

• Journal of Mechanical Science and Technology
• /
• 제17권5호
• /
• pp.629-636
• /
• 2003

This paper introduces the developed geometry PIG (Pipeline Inspection Gauge), one of several ILI (In-Line Inspection) tools, which provide a full picture of the pipeline from only single pass, and has compact size of the electronic device with not only low power consumption but also rapid response of sensors such as calipers, IMU and odometer. This tool is equipped with the several sensor systems. Caliper sensors measure the pipeline internal diameter, ovality and dent size and shape with high accuracy. The IMU (Inertial Measurement Unit) measures the precise trajectory of the PIG during its traverse of the pipeline. The IMU also provide three-dimensional coordination in space from measurement of inertial acceleration and angular rate. Three odometers mounted on the PIG body provide the distance moved along the line and instantaneous velocity during the PIG run. The datum measured by the sensor systems are stored in on-board solid state memory and magnetic tape devices. There is an electromagnetic transmitter at the back end of the tool, the transmitter enables the inspection operators to keep tracking the tool while it travels through the pipeline. An experiment was fulfilled in pull-rig facility and was adopted from Incheon LT (LNG Terminal) to Namdong GS (Governor Station) line, 13 km length.

• 한국지능시스템학회논문지
• /
• 제24권6호
• /
• pp.651-656
• /
• 2014

부식결함은 가스배관의 신뢰성평가 및 정비계획에 유의한 영향을 미친다. 부식결함은 정기적인 ILI를 통해 수집할 수 있지만 ILI 데이터의 효과적인 분석은 아직 미흡한 실정이다. 본 논문은 부식결함이 존재할 때 가스배관의 잔여수명을 예측하는 문제를 다룬다. 실제 운용 환경에서 배관 파라미터는 불확실성의 영향 하에 놓이게 되므로 확률적인 접근방법을 채택한다. 배관의 고장은 그 운용압력이 배관파열압력보다 클 때 발생하는 것으로 볼 수 있다. 따라서 배관의 고장확률은 운용압력이 배관파열압력보다 클 확률로서 정의된다. 이를 계산하기 위해 본 논문에서는 구조공학 분야에서 널리 쓰이는 First Order Reliability Method (FORM) 알고리즘을 이용한다. 배관파열압력을 얻기 위한 모델은 잘 알려진 Battelle 코드를 채택한다. ILI 데이터가 주어질 때 고장확률을 계산하는 과정은 Matlab GUI를 통해 제시하고 특히 부식결함의 클러스터링이 계산결과에 미치는 영향을 논의한다. 본 논문의 결과는 고장확률 추정의 정밀도를 높이고 효율적인 정비정책을 수립하는데 적절한 클러스터링이 필요함을 시사한다.

• Journal of Magnetics
• /
• 제15권4호
• /
• pp.199-203
• /
• 2010

This paper discusses the effectiveness of high magnetization saturation in ILI (In-Line Inspection) using an MFL (Magnetic Flux Leakage) tool, and introduces a practical method for improving the magnetization level together with the piggability. Thin steel plates, replacing the conventional wire brushes were used as conductors to transfer the magnetic flux to the pipe wall. The newly designed MFL tool was compared with the conventional version by means of FEM (Finite Element Method) analysis and full-scale experiments. In the results, the newly developed magnetization system obtained a stronger MFL signal amplitude, specially 2.7 times stronger, than that obtained by the conventional magnetization system for the same defect dimensions.

• Journal of Magnetics
• /
• 제16권1호
• /
• pp.36-41
• /
• 2011

If gas is leaking out of gas pipelines, it could cause a huge explosion. Accordingly, it is important to ensure the integrity of gas pipelines. Traditionally, over the years, gas-operating companies have used the ILI system, which is based on axial magnetic flux leakage (MFL), to inspect the gas pipelines. Relatively, there is a low probability of detection (POD) for the axial defects with the axial MFL-based ILI. To prevent the buried pipeline from corrosion, it requires a protective coating. In addition to the potential damage to the coating by environmental factors and external forces, there could be defects on the damaged coating area. Thus, it is essential that nondestructive evaluation methods for detecting axial defects (axial cracks, axial groove) and damaged coating be developed. In this study, an electromagnetic acoustic transducer (EMAT) sensor was designed and fabricated for detecting axial defects and coating disbondment. In order to validate the performances of the developed EMAT sensor, experiments were performed with specimens from axial cracks, axial grooves, and coating disbondment. The experimental results showed that the developed EMAT sensor could detect not only the axial cracks (minimum 5% depth of wall thickness) and axial grooves (minimum 10% depth of wall thickness), but also the coating disbondment.