• Corrosion Science and Technology
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• 제8권3호
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• pp.119-125
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• 2009

Corrosion assessment has a number of uses but the use considered here is as a precursor to Risk-Based Inspection (RBI) planning. Systematic methods consisting of technical modules of RBI program were used to assess the effect of specific corrosion mechanism on the probability of failure in equipments of petrochemical plants. Especially in part of the damage and corrosion assessment, screening step involved evaluating the combinations of process conditions and construction materials for each equipment item in order to determine which damage mechanisms are potentially active. For general internal corrosion, either API 510 or API 570 was applied as the damage rate in the calculation to determine the remaining life and inspection frequency. In some cases, a measured rate of corrosion may not be available. The technical modules of RBI program employ default values for corrosion, typically derived from published data or from experience with similar processes, for use until inspection results are available. This paper describes the case study of corrosion and damage assessment by using RBI methodology in petrochemical plant. Specifically, this paper reports the methodology and the results of its application to the petrochemical units using the $KGS-RBI^{TM}$ program, developed by the Korea Gas Safety Corporation to suit Korean situation in conformity with API 581 Codes.

• Corrosion Science and Technology
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• 제14권3호
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• pp.147-152
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• 2015

Corrosion of steel reinforcement is a major factor in the deterioration of harbour and bridge structure. Steel corrosion in concrete must be checked for assessing the condition of a reinforced concrete structure. There are several ways how to measure the corrosion condition of reinforced concrete, but the corrosion potential measurement is a very simple, rapid, cost-effective and non-destructive technique to evaluate the severity of corrosion in reinforced concrete structure, therefore commonly used by engineers. However some particular situations may not relate to the reinforcement corrosion probability and a simple comparison of the corrosion potential data with the ASTM C876 Standard on steel reinforcement corrosion probability could be meaningless and not give reliable informations because of environment factors as oxygen concentration, chloride content, concrete resistance. Therefore this paper explains the risk of corrosion assessment in reinforced concrete structure and how many factors can affect the reliability of the corrosion potential data.

• 한국정밀공학회지
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• 제17권12호
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• pp.157-162
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• 2000

The object of this work is to develop an assessment system for pipeline integrity. the system consists of four module applications for internal algorithm; the effect of corrosion in pipeline, crack, stress corrosion crack (SCC) and fatigue modules. Presently, the module of the external corrosion has been developed and the internal algorithm for the effect of corrosion in pipeline and the database of the system are described in this paper. The database of the system is separated to mainly four parts; geometry of pipeline, material properties, boundary conditions and general properties. Each components of the system are designed by user-friendly concept. This system may give a guideline for maintenance and modifications for the pipeline at the industrial sight. Furthermore, a procedure to evaluate an inspection interval is also provided.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.228-233
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• 2004

The length of city gas pipeline is increasing with expansion of natural gas transmission rapidly. A lot of the expense was paid for repair and maintenance with increasing of pipeline length and the cost of repair and maintenance by the corrosion was the highest. It is necessary to evaluate integrity in case of thickness reduction by corrosion. There are a lot of assessment criteria for corrosion defect in foreign countries but they are not suitable for application in the country directly. In this work, we performed the burst test and the finite element analysis for city gas pipeline, KS D3507 and KS D3631 for city gas transmission, and developed the assessment method of corrosion defect, which is suitable for domestic condition.

• 대한토목학회논문집
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• 제26권2A호
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• pp.293-300
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• 2006

일반적으로 부식된 부재의 두께를 측정하는 데는 많은 불확실성이 존재하며, 부식의 진행정도에 따라 부재의 부식 두께는 측정 위치마다 다르므로, 기존의 신뢰성 해석 방법을 사용하여 모든 불확실성을 고려한 정량적인 안전도를 평가하는 것은 실질적으로 불가능하다. 따라서 본 논문에서는 불확실 신뢰도 기법을 적용한 안전도 분석 절차를 제안하였으며, 효율성과 적용성을 검토하기 위하여 국내 공용중인 사장교에 적용하였다. 심하게 부식된 부재의 잔존 두께의 불확실성은 부식이 진행되는 정도에 따라 증가하므로 부재의 부식 두께를 불확실 정도로 표현되는 불확실 구간으로 표현하였으며, 기존의 신뢰성 기법과 불확실 신뢰도 기법의 비교를 수행하였다. 이러한 불확실 신뢰도 기법은 주관적이거나 조건부 독립에 대한 통계적 판단을 이용하여, 부식된 구조물의 안전도 평가나 위험도 평가를 하는 경우에 유용하여 적용할 수 있을 것으로 판단된다.

• International Journal of Precision Engineering and Manufacturing
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• 제1권2호
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• pp.48-54
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• 2000

This paper presents the effect of shape of external corrosion in pipeline on failure prediction by using a numerical simulation. The numerical study for the pipeline failure analysis is based on the FEM(Finite Element Method)with an elastic-plstic and large-deformation analysis. Corrosion pits and narrow corrosion grooves in pressurized pipeline were analysed. A failure criterion, based on the local stress state at the corrosion and a plastic collapse failure mechanism, is proposed. The predicted failure stress assessed for the simulated corrosion defects having different corroded shapes along the pipeline axis compared with those by methods specified in ANSI/ASME B31G code and a modified B31G code. It is concluded the corrosion geometry significantly affects the failure behavior of corroded pipeline and categorisation of pipeline corrosion should be considered in the development of new guidance for integrity assessment.

• 한국해양공학회지
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• 제29권1호
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• pp.100-110
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• 2015

To meet the increasing demand for energy around the world, offshore and subsea energy development is constantly being conducted. This trend is accompanied by an increasing demand for pipeline installation, which brings numerous problems, including those related to accessibility, high pressure, and corrosion. Among these, corrosion is a primary factor in pipeline fractures, and can cause severe environmental and industrial damage. Hence, accurate corrosion assessment for corroded pipelines is very important. For this reason, the present study investigated the mechanical behavior of an idealized corroded subsea pipeline with an internal/external pressure load using the commercial FEA code ABAQUS. Then, the analysis result was compared with corrosion assessment codes such as ASME B31G, DNV RP F101, ABS. Finally, a fitness-for-service assessment was conducted.

• 한국가스학회지
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• 제18권5호
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• pp.12-19
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• 2014

매설배관의 부식위험성을 최소화하고 음극방식의 효율극대화를 위해 다양한 비굴착 간접검사기법들이 수십년 전부터 이용되고 있으며, 미국에서는 굴착을 통한 매설배관 외면부식 직접평가법을 CFR 코드에서 규정하고 있다. 국내의 경우에는 도시가스사업법 관련 4개의 기준(KGS Code)에서 배관의 손상여부를 측정할 수 있는 장비를 이용하여 배관의 상태를 점검, 측정하고 이상부위에 대하여 누출검사를 한 경우 매설배관의 기밀시험을 한 것으로 보고 있을 뿐 배관외면부식 직접평가에 대한 규정은 없다. 본 논문에서는 미국, 영국 등 국외의 매설배관 건전성 관리 기준 및 방법을 조사하고, 국내의 매설배관 방식관리 실태 및 피복손상탐지 장치 이용실태 등을 조사한 후 국내 실정에 맞는 매설배관 외면부식 직접평가법을 제시하였다. 본 논문에서 제시한 매설배관 외면부식 직접 평가법은 국내에서 중압배관의 정밀안전진단 제도를 도입하는데 기초 자료로 활용되었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.361-366
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• 2002

The deterioration of concrete structure due to corrosion of the reinforcement has created big financial losses on the overall industries. The volume expansion of the corrosion products causes internal pressure to concrete wall around reinforcing bar. If the maximum principal stress induced by internal pressure exceeds the tensile strength of the concrete at any point of time, a crack forms at any point of material. Therefore, in terms of life assessment of concrete structure, it is very important to predict the amount of corrosion products which induces initial concrete cracking. With this objective, this paper proposes the critical amount of corrosion products at interface between reinforcement and concrete using finite element analysis. If an actual survey of corrosion rates could be made, the model might supply information for condition assessment of existing concrete structure. As the mechanical properties of corrosion product and instantaneous geometry of corroded steel are considered in the analysis, the value obtained will be more realistic.

• 콘크리트학회논문집
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• 제12권5호
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• pp.69-80
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• 2000

This paper presents the prediction of remaining service life of the concrete due to steel corrosion caused by the following three cases; carbonation, using sea sand and using deicing salts. The assessment of initiation period was generalized considering the existing perdiction models in the literature, corrosion experiment and field assessment. To evaluate the prediction equation of rust growth, the corrosion accelerating experiments was performed. The polarization resistance was measured by potentiostat and the conversion coefficient of polarzation resistance to corrosion rate was determined by the measurement of real mass loss. Chloride content, carbonation, cover depth, relative humidity, water-cement ratio(W/C), and the use of deicing salts were taken into account and the resulting prediction equation of rust growth was proposed on the basis of these properties. The proposed equation is to predict the rust growth during any specified period of time and be effective in particular for predicting service life of concrete in the case of using sea sand.