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The aim of this paper is to investigate the failure probability in an irregular area in pipeline (elbow) over its lifetime. The reliability analysis is performed by using of an enhanced first-order reliability method / second-order reliability method (FORM/SORM) and Monte Carlo simulation methods: a numerical model of a corroded pipeline elbow was developed by using finite element method; also, an empirical mechanical behavior model has been proposed. A numerical case with high, moderate and low corrosion rates was conducted to calculate the deferent reliability indexes. The found results can be used in an application case for managing an irregular area in pipeline lifetime. Hence, it is necessary to ensure a rigorous inspection for this part of a pipeline to avoid human and environmental disasters.

The present paper deals a methodology for estimating time-dependent reliability of a corroded pipeline elbow. Firstly, a numerical model of corroded elbow is proposed by using the finite element method. A mechanical behavior under the corrosion defect in time is studied, and an empirical model was also developed.

The result of this paper can be summarized as: a mechanical characterization of the material was carried out experimentally. A numerical model of a corroded pipeline elbow was developed by using the finite element method. An empirical mechanical behavior model has been developed. The reliability of a corroding pipe elbow can be significantly affected by corrosion and residual stress. A proportional relationship has been found between probability of failure and corrosion rate. The yield stress and pressure service have an important sensitivity factor.

Aiming to help Algerian gas and oil companies' decision makers, the present paper illustrates a methodology for estimating time-dependent reliability of a corroded pipeline elbow over its lifetime using numerical models by applying the finite element method. Firstly, a numerical model of a corroded pipe elbow was developed and coupled with an empirical mechanical behavior model, which is also proposed. A probabilistic is then developed to provide realistic corrosion parameters and time modeling, leading to the real impact on the lifetime of an elbow zone in pipeline. The reliability indexes and probability of failure for various corrosion rates with and without issued residual stress are computed using Monte Carlo simulation and FORM.

Gas pipelines are facing serious risk because of the factors such as long service life, complex working condition and most importantly, corrosion. As one of the main failure reasons of gas pipeline, corrosion poses a great threat to its stable operation. Therefore, it is necessary to analyze the reliability of gas pipelines with corrosion defect. This paper uses the corresponding methods to predict the residual strength and residual life of pipelines.

In this paper, ASME-B31G revised criteria and finite element numerical analysis software are used to analyze the reliability of a special dangerous section of a gas gathering pipeline, and the failure pressure and stress concentration of the pipeline under three failure criteria are obtained. Furthermore, combined with the predicted corrosion rate of the pipeline, the residual service life of the pipeline is calculated.

This paper verifies the feasibility of ASME-B31G revised criteria and finite element numerical analysis methods for reliability analysis of gas pipelines with corrosion defect. According to the calculation results, the maximum safe internal pressure of the pipeline is 9.53 Mpa, and the residual life of the pipeline under the current operating pressure is 38.41 years, meeting the requirements of safe and reliable operation.

The analysis methods and analysis results provide reference basis for the reliability analysis of corroded pipelines, which is of great practical engineering value for the safe and stable operation of natural gas pipelines.

The reliability and corrosivity of two VOC ‐ free, no‐clean fluxes (C and D) were assessed using traditional test method such as copper mirror and copper corrosion tests. Modified surface insulation resistance (SIR) tests using coupons fluxed with various methods were performed in 50°C/90%RH environmental conditions. Printed circuit boards and assemblies were fluxed and exposed to a 50°C/90%RH chamber to assess long‐term reliability. To evaluate the corrosion rates of copper and solder sheets in as‐ received liquid fluxes, electrochemical polarisation measurements were employed. These showed that the corrosion rate of copper in flux D is 100 times higher than that in flux C. These quantitative data agreed with the qualitative copper mirror test results, i,e, flux C passed and flux D failed the test. However, both flux residues were found to corrode copper traces underneath the solder mask and copper pads on the PCB after three weeks in a 50°C/90% RH environment chamber. Large amounts of blue/green corrosion products were observed on the bare copper SIR coupons within seven days when using either flux; and SIR values were below the required 10₈ ohms. Based on the test results, neither flux was qualified for no‐clean processes because of the issues with corrosion. The corrosiveness of the VOC‐ free, no‐ clean flux residue is believed to be due to the activator packages used.

THE reliability of ships' structures and machinery is of utmost concern to activities in a marine environment. Corrosion can have a major effect on this reliability. A number of practical examples will be discussed to illustrate the corrosion hazards that appear between design office and field execution, the weaknesses inherent in some commonly used metals, and how an understanding of corrosion can be of major significance in ensuring reliability.

The aim of this study is to assess the opportunity for the development of hydrocarbon transportation using high-strength steel (HSS) in pipeline construction in terms of cost savings and reliability.

Several optimizations of pipeline design and operations were performed to estimate the total life-cycle cost variation associated with different grades of high-strength steel. The generalized reduced gradient (GRG) method was used in an Excel table to determine optimal total life cycle each pipeline. Variables used in this optimization with respect to each steel grade were as follows: pipeline external diameter, wall thickness, number of compression stations and installed power in each compression station. The reliability of a pipeline with optimal cost was assessed to highlight the impact of steel grade on pipeline reliability.

The study showed that the cost reduction is strongly dependent on the adopted gas pipeline configuration. The number of compression stations and external diameter are the main factors influencing the pipeline total life cycle cost, while the steel price seems to have a minor effect, the reduction of the gas pipeline total life cycle does not exceed 5% even with a 50% difference in pipe steel prices between X70 and X100 steels. On the other side, for the same external diameter, X100 steel presents better pipeline reliability against carbonic corrosion compared to X70 steel.

The main contribution of this study is to provide a decision-support tool to help pipeline constructors enhance the profitability of natural gas transmission pipelines. The optimization method used is simple to use for design engineers during a feasibility study.

The present study presents one step to fill the gap concerning the question of balancing the trade-off between cost savings and structural reliability in high-strength steel pipelines during the early stages of feasibility studies. The optimal design and operations parameters ensuring cost savings on total life cycle costs are identified via an optimization method. The impact of selected optimal parameters on the long-term pipeline service life was estimated via a structural reliability analysis.

‘No clean’ fluxes (NCFs) have been in existence for a few years now. The initial claimed advantages of these fluxes were that post flow soldering cleaning would not be required, therefore a substantial cost‐reduction could be obtained in terms of no cleaning plant or cleaning solvent being necessary, and a consequent reduction in floor space requirements. Latterly, the restrictions to be placed on the manufacture of CFCs (the major flux cleaning solvent) via the Montreal Protocol have given these NCFs a much higher level of prominence. The advantages claimed for NCFs are very attractive; however, the fluxes represent a considerable technology shift from the conventional high solids rosin type fluxes which have been successfully used for many years. Probably the most important questions to be raised when considering their use are: ‘Will any remaining residue be corrosive and will the long‐term reliability of the printed circuit boards be affected?’ This paper sets out to address the following issues: (a) A definition of corrosion and long‐term reliability and what it means in practical terms, (b) an understanding of the basic formulation of NCFs and (c) evaluation and selection of test methods to establish confidence that corrosion and reduction in long‐term reliability, as described in (a), will not occur.

The purpose of this paper is to investigate the decomposition behavior of binary mixtures of organic activators commonly used in the no-clean wave flux systems upon their exposure to thermal treatments simulating wave soldering temperatures. The binary blends of activators were studied at varying ratios between the components.

Differential scanning calorimetry and thermogravimetric analysis were used to study the characteristics of weak organic acid (WOA) mixtures degradation as a function of temperature. The amount of residue left on the surface after the heat treatments was estimated by gravimetric measurements as a function of binary mixture type, temperature and exposure time. Ion chromatography analysis was used for understanding the relative difference between decomposition of activators in binary blends. The aggressivity of the left residue was assessed using the acidity indication gel test, and effect on reliability was investigated by DC leakage current measurement performed under varying humidity and potential bias conditions.

The results show that the typical range of temperatures experienced by electronics during the wave soldering process is not sufficient for the removal of significant activator amounts. If the residues contain binary mixture of WOAs, the final ratio between the components, the residue level and the corrosive effects depend on the relative decomposition behavior of individual components. Among the WOA investigated under the conventional wave soldering temperature, the evaporation and removal of succinic acid is more dominant compared to adipic and glutaric acids.

The findings are attributed to the chemistry of WOAs typically used as flux activators for wave soldering purposes. The results show the importance of controlling the WOA content and ratio between activating components in a flux formulation in relation to its tendencies for evaporation during soldering and the impact of its residues on electronics reliability.

The results show that the significant levels of flux residues can only be removed at significantly higher temperatures and longer exposure times compared to the conventional temperature range used for the wave soldering process. The potential corrosion issues related to insufficient flux residues removal will be determined by the residue amount, its composition and ratio between organic components. The proper time of thermal treatment and careful choice of fluxing formulation could ensure more climatically reliable product.

The paper aims to develop an intelligent anti-corrosion expert system based on browser/server (B/S) architecture to realize an intelligent corrosion management system.

The system is based on Java EE technology platform and model view controller (MVC) three-tier architecture development model. The authors used an extended three-dimensional interpolation model to predict corrosion rate, and the model is verified by cross-validation method. Additionally, MySQL is used to realize comprehensive data management.

The proposed anti-corrosion system thoroughly considers a full use of corrosion data, relevant corrosion prediction and efficient corrosion management in one system. Therefore, this system can achieve an accurate prediction of corrosion rate, risk evaluation, risk alert and expert suggestion for equipment in petrochemical plants.

Collectively, this present study has important ramifications for the more efficient and scientific management of corrosion data in enterprises and experts’ guidance in controlling corrosion status. At the same time, the digital management of corrosion data can provide a data support for related theoretical researches in corrosion field, and the intelligent system also offers examples in other fields to improve system by adding intelligence means.

Corrosion is one of the common damage mechanisms in many engineering structures such as marine structures, petroleum pipelines, aerospace and nuclear reactor. However, the service performance of metal materials and structures is gradually degenerating with the increase of service life due to the rapid growth of corrosion damages. Thus, the coupled effects for corrosion damage in reliability analysis should be considered urgently. Then, the purpose of this paper is to develop the corrosion damage physical model and the corresponding reliability analysis methods, which consider the coupled effect of corrosion damage.

A failure physical model, considering the coupled effect of pitting growth, crack and crack propagation, is presented in this paper. Sequentially, the corrosion reliability with respect to pitting physical damage can be investigated. The presented pitting damage physical model is formulated as time-variant performance limit state functions, which include the crack transition, crack growth and fracture failure mechanics. The first-passage failure criterion is used to construct the corrosion reliability framework, involving in the pitting damage model with the increase of service life.

Results demonstrate that the multiplicative dimensional reduction (MDR) method behaves much better than FORM no matter in accuracy or efficiency. The proposed corrosion reliability method is applicable for dealing with the damage failure model of the structural pitting corrosion.

The MDR method is used to calculate the corrosion reliability index of a given structure with fewer function calls. Finally, an aeronautical metal material is used to demonstrate the efficiency and precision of the proposed corrosion reliability method when the failure physical model considering the coupled effects of mechanical stresses and corrosion environment is adopted.

In the freeze-thaw zone, the pre-stressed concrete of bridge structure will be damaged by freezing-thawing, the bearing capacity of structure will decrease and the safety will be affected. The purpose of this paper is to establish the time-dependent resistance degradation model of structure in the freeze-thaw zone, and analysis the structural reliability and remaining service life in different freeze-thaw zones.

First, according to the theory of structural design, a calculation model of the resistance of pre-stressed concrete structures in f freeze-thaw zone is established. Second, the time-dependent resistance model was verified by the test beam bending failure test results done by the research group, which has been in service for 20 years in freeze-thaw zone. Third, using JC algorithm in MATLAB to calculate the index on the reliability of pre-stressed concrete structure in frozen thawed zones, forecasting the s remaining service life of structure.

First, the calculation model of the resistance of pre-stressed concrete structures in freeze-thaw zone is accurate and it has excellent applicability. Second, the structural resistance deterioration time in Wet-Warm-Frozen Zone is the earliest. Third, once the pre-stressed reinforcement rusts, the structural reliability index will reach limit value quickly. Finally, the remaining service life of structure meets the designed expectation value only in a few of freeze-thaw zones in China.

The research will provide a reference for the design on the durability of a pre-stressed concrete structure in the freeze-thaw zone. In order to verify the security of pre-stressed concrete structures in the freeze-thaw zone, engineers can use the model presented in this paper for durability checking, it has an important significance.