基于RBI的苯乙烯/环氧丙烷装置压力管道在线检验研究

对苯乙烯／环氧丙烷装置进行腐蚀回路划分,并将腐蚀回路中的压力管道按照管径、材质及用途等因素划分为不同的组别后进行RBI分析。根据风险评估结果,结合压力管道的使用情况、失效机理及剩余使用寿命等确定下一个检验周期和检验策略。以腐蚀回路中的组别作为检验单元,根据其失效可能性及风险等级确定各检验单元的检验比例和检验方法进行在线检验。结果表明：基于RBI分析结果的压力管道在线抽检方法可以验证风险评估的结果,同时还可以满足使用单位对管道的风险控制要求。     

基于RBI技术的化工装置压力管道风险评估与在线检验策略研究

基于RBI方法原理,实施化工装置压力管道风险评估。在风险评估过程中,将装置内各腐蚀回路中的压力管道按照管径、材质及用途等因素进行分组,以得到各压力管道组的风险等级,在此基础上确定其抽检比例,制订在线检验策略。以某厂环氧乙烷/乙二醇〖JP2〗（EO/EG）装置为对象,应用壳牌S-RBI软件完成装置内274组（共458条）压力管道风险评估工作,根据风险评估结果共抽取178条压力管道实施在线检验,考虑到该装置存在的减薄机理,在线检验技术手段以测厚和宏观检查为主,并对部分中高风险等级以上的压力管道进行数字射线检测。检验结果表明:基于RBI技术的压力管道在线检验策略能够有效发现压力管道系统中存在的安全隐患,并节约检验成本。     

基于RBI的碳五石油树脂装置风险评估分析

从技术特点、实施效用等方面,对QRA与RBI两类风险评估技术进行比较,选择使用RBI技术方法对碳五石油树脂装置内静设备及管道实施风险评估。运用挪威船级社的ORBIT Onshore软件定量计算评估范围内设备、管道风险值,评定风险等级,辨识隐患设备,然后从后果、可能性两方面分析产生风险的主要影响因素,经分析得知碳五石油树脂装置受H2S、HCl腐蚀减薄影响轻微,但NaOH导致的碱应力腐蚀对聚合反应后序工段中部分管道设备失效可能性影响较大。最后根据装置内存在的不同损伤机理提出检验优化策略,为装置定期检验工作提供科学的决策支持。     

Risk-based inspection for large-scale crude oil tanks

Periodic Internal Inspection Method often results in under-inspection or over-inspection for large-scale crude oil tank. Therefore, how to determine reasonable internal inspection interval (INTII) has great significance on balancing the safe operation requirement and inspection cost for crude oil tanks. Here, RBI (risk-based inspection) technology is used to quantitatively assess the risk of crude oil tanks in an oil depot in China. The risk comparison between tank shell and bottom shows that the risk of tank depends on the risk of tank bottom. The prediction procedure of INTII for crude oil tanks is also presented. The INTII predicted by RBI method is gradually extended with the increasing of the acceptable risk level. The method to determine the acceptable risk of crude oil tanks is proposed, by which 3.54E+04 are taken as the acceptable risk of the oil depot. The safety factor of 0.8 is proposed to determine the final INTIIs for 18 crude oil tanks. The INTII requirement in China code SY/T 5921, 5-7 years, is very conservative and lower than predicted service life of tanks. The INTIIs predicted by Gumbel method are smaller than by RBI method for tanks with short INTII. Therefore, this paper recommends RBI method to predict the INTII for crude oil tanks.     

Risk-based inspection (RBI) of a gas pressure reduction station

One of the principles of corrosion management is proper inspection methodology, and in particular the risk-based inspection (RBI). Occasionally a large percentage of the total risk of a unit is concentrated in a small part of the equipment, which can be reduced by using risk management techniques. In this study, a semi-quantitative risk-based inspection method has been performed in a gas station with for its components (pipelines, filters, etc.), to identify the existing damage mechanisms and also to rank its equipment in terms of inspection intervals. In this regard, RBI was performed for the gas station which consisted of phases (Phase A & Phase B) with Class 300 and Class 600 equipment. According to documented conditions and reviewed records the main damage mechanism for the investigated components in the gas station was identified as wall thinning due to erosion corrosion and external corrosion. In terms of inspection, results showed that most of the equipment studied had medium risk level and a few had medium to high level of risk. In this regard, the corrosion rates of Class 300 and Class 600 equipment were also studied and compared, and it was indicated that the corrosion rates were higher at locations for Class 300 equipment where more pressure drop had occurred. Overall, based on the obtained corrosion rates and obtained risk matrixes, it was concluded that wall thinning (erosion-corrosion) was the determining risk factor for equipment inspected in the gas pressure reduction station.     

Utilizing Integrity Operating Windows (IOWs) for enhanced plant reliability & safety

Several industry codes, standards and recommended practices have been developed and utilized to maintain pressure equipment integrity and improve reliability. These industry standards focus heavily on inspections (time or risk based) and guidelines for operating equipment at conditions that enable a tolerable deterioration rate. RBI (risk based inspection), in effect, utilizes process conditions at a snapshot in time to recommend inspection strategies which can cover the span of the equipment's remaining life. On a day to day level, changes that occur in process conditions (excursions and upsets) are not fed back into the risk and criticality calculation. When such changes to operating conditions affect key process variables, new damage mechanisms could be introduced that affect the remaining life of an asset or accelerate existing damage mechanisms. The increase in risk resulting from these process changes goes unaccounted for until the effect of the deterioration is captured at the next inspection.Integrity Operating Windows (IOWs) are established limits for key process variables that can affect the integrity of the equipment if the process operation deviates from the established limits. The development of these IOWs requires fundamental understanding of the process and resulting damage mechanisms and is best facilitated by a team of corrosion and process engineers along with feedback from plant operators. A well-established IOW program is designed to provide real time notification of an increased risk to the integrity of an asset so that identified actions can be taken by the operators and/or plant managers proactively in a timely manner. Combining an RBI program with an IOW program can greatly increase its effectiveness and provide early recognition of equipment risks due to process changes. This paper will focus on the development of an IOW program and the benefits of combining it with a viable RBI program.     

An evaluation of maintenance strategy using risk based inspection

Risk based inspection (RBI) methodology was proposed to evaluate the maintenance strategy in industrial process which was constructed in one of the units of Fujian Oil Refinery ISOMAX unit. Using classic definition of risk, both the probability and consequence of accident or failure were investigated respectively under the support of risk-specific code. All equipment in this unit were evaluated and categorized into five risk zone based on the RBI result which covered five levels. In addition, an application of the analytical hierarchy process (AHP) to select the most practicable maintenance strategy for equipment which was located in each risk rating scale was described. To arrange the hierarchic structure and evaluation, four main criteria were defined for pairwise judgments. Finally, four possible alternative strategies were proposed for administrators on the site.     

丁二烯装置基于风险的检验技术应用

采用RBI技术对丁二烯装置进行风险评估,经分析装置存在的主要损伤机理有碱应力腐蚀开裂、有机酸腐蚀、冷却水腐蚀、冲刷腐蚀和丁二烯自聚等,装置的风险由失效后果主导,失效可能性较高的评估.单元集中在脱重冷凝系统和薄壁小直径管道。根据基于风险的检验策略对装置实施检验,检验过程中发现装置存在脱重冷凝系统设备应力腐蚀开裂、一萃塔系统换热器点蚀、接管角焊缝开裂和压力管道腐蚀減薄等主要问题,检验检测结果与风险评估过程中识别的损伤机理和薄弱环节保持一致。     

Hydrogen explosion incident mitigation in steam reforming units through enhanced inspection and forecasting corrosion tools implementation

Hydrogen (H₂) explosion effects recently examined, are confirming the devastating loss scenarios to humans, environment, assets, and associated business interruption. H₂ production is a core process in refineries used in further process steps. Steam reforming of natural gas or a mix with naphtha or LPG is a common hydrogen production technique, where the latest technologies have adopted enhanced metallurgies to minimize explosion risk and the associated maintenance cost following plant degradation owing to corrosion effects. However, corrosion rates are still high in specific areas of piping and process equipment. The aim of this paper is to present a methodology based on semi-quantitative RBI modeling according to regulations by API and recent EN standards, adopting a family of linear regression forecasting models that depict the yearly corrosion rate (per corrosion loop) of a hydrogen production steam reforming unit; this is done under different operating conditions (e.g., temperature, pressure, and fluid speed), metallurgy and other related physicochemical variables. The model is based on the examination of both ultrasonic wall thinning measurements and the examination of quantitative crosslinking total corrosion effects along with the physicochemical properties prevailing in different plant corrosion loops. The outcome of the regression analysis is an expansive family of multivariable equations describing, with a defined accuracy, the yearly corrosion rate and associated lifespan forecast per corrosion loop, and per examined part. These equations were further utilized in a custom-made database that can be used as an additional loss prevention tool by the hydrogen production unit management team. Evaluation results regarding the tool efficiency are presented in the following of this paper.     

RBI技术在我国企业的应用研究与改进思考

基于风险的检测技术(RBI)是目前化工行业逐渐采用并得到认可的一种新的设备检测技术。在对RBI体系研究的基础上,阐述了RBI的系统思想、实施步骤与应用价值;在工艺危害性分析的基础上,采用挪威船级社的ORBIT Onshore软件对常减压装置进行了定量RBI分析,识别出装置设备和管道的主要腐蚀损伤模式,确定设备和管道的风险大小分布以及风险检测策略;并根据RBI在化工等行业企业的应用实践对RBI技术在我国应用过程中存在的不足提出了相关改进建议。     

Development and application of equipment maintenance and safety integrity management system

Equipment management in process industry in China essentially belongs to the traditional breakdown maintenance pattern, and the basic inspection/maintenance decision-making is weak. Equipment inspection/maintenance tasks are mainly based on the empirical or qualitative method, and it lacks identification and classification of critical equipment, so that maintenance resources can’t be reasonably allocated. Reliability, availability and safety of equipment are difficult to control and guarantee due to the existing maintenance deficiencies, maintenance surplus, potential danger and possible accidents. In order to ensure stable production and reduce operation cost, equipment maintenance and safety integrity management system (MSI) is established in this paper, which integrates ERP, MES, RBI, RCM, SIL and PMIS together. MSI can provide dynamic risk rank data, predictive maintenance data and RAM decision-making data, through which the personnel at all levels can grasp the risk state of equipment timely and accurately and optimize maintenance schedules to support the decision-making. The result of an engineering case shows that the system can improve reliability, availability, and safety, lower failure frequency, decrease failure consequences and make full use of maintenance resources, thus achieving the reasonable and positive result.     

A framework to estimate the risk-based shutdown interval for a processing plant

Petrochemical plants and refineries consist of hundreds of pieces of complex equipment and machinery that run under rigorous operating conditions and are subjected to deterioration over time due to aging, wear, corrosion, erosion, fatigue and other reasons. These devices operate under extreme operating pressures and temperatures, and any failure may result in huge financial consequences for the operating company. To minimize the risk and to maintain operational reliability and availability, companies adopt various maintenance strategies. Shutdown or turnaround maintenance is one such strategy. In general, shutdown for inspection and maintenance is based on the original equipment manufacturer's (OEM) suggested recommended periods. However, this may not be the most optimum strategy given that operating conditions may vary significantly from company to company.The framework proposed in this work estimates the risk-based shutdown interval for inspection and maintenance. It provides a tool for maintenance planning and decision making by considering the probability of the equipment or system for failure and the likely consequences that may follow. The novel risk-based approach is compared with the conventional fixed interval approach. This former approach, characterized as it is by optimized inspection, maintenance and risk management, leads to extended intervals between shutdowns. The result is the increase in production and the consequent income of millions of dollars.The proposed framework is a cost effective way to minimize the overall financial risk for asset inspection and maintenance while fulfilling safety and availability requirements.     

基于风险的检验(RBI)在国内合成氨装置中的应用

利用API581基于风险的检验原理,采用RISKWISE分析软件对九江石化合成氨装置中的设备和管道进行了风险评估;并在装置采用的工艺、不同装置的设备和管道的失效机理和计算出的风险分布这3方面,将其风险评估结果与国内兄弟单位完成的其他合成氨装置的风险评估结果进行了比对;其结果体现了我国目前合成氨装置的设备和管道风险的大致分布,可供我国其他合成氨装置的风险评估参考,也为制定我国合成氨装置基于风险检验的法规标准提供了相关数据;同时,对国内采用针对装置的基于风险的检验的新模式进行了探讨。     

基于风险的检验技术在苯加氢装置管道的应用

简述基于风险的压力管道检验技术基本理念,讨论压力管道的危害风险和失效模式,介绍了风险评估方法及其适用场合、风险评估程序。对某苯加氢装置的管道系统进行风险检验评价,对该管道的各种危险因素进行分析,并对其基础数据和检验检测结果进行了研究和探讨,近而采用5×5风险矩阵法和定性分析,对苯加氢装置管道系统进行风险评估,根据该评估结论,提出了科学制定检修计划的建议和控制风险措施。研究结果表明:基于风险的检验技术,既能节约大量的停机和检验维修费用,又能有效地提高重点设备的安全性和管理水平。     

基于JC法的RBI通用失效概率修正模型研究

基于风险的检测技术失效概率的分析始于同类设备的失效频率数据库,然后通过设备修正因子和管理系统评价因子来修正这些同类频率。针对RBI的不足,结合可靠度理论,分析均值一次二阶矩法在实际应用过程中局限性,应用基于JC法的通用失效概率计算模型完成设备失效概率的修正。该方法适合任何概率分布下的情况,可以避免统计数据正态分布一刀切的缺点。     

基于RBI技术的海上平台延期服役静设备定量化安全评估技术

针对海上延期服役平台静设备的安全风险评估与控制问题,应用RBI风险评估技术的评估理论和方法对海上延期服役平台静设备的定量化安全管理方法进行了实践和探索,并选择某延期服役平台进行风险分析相关结论的工程验证。其具体过程是运用定量RBI技术,首先根据工艺流程和介质特点对海上平台静设备分别进行了物流回路和损伤回路的划分,并以此为基础对延期服役平台静设备的安全风险进行定量评估,进而得出各静设备单元的失效可能性、失效后果及风险等级,最后通过得出的损伤模式、损伤机理及对应的腐蚀速率,从而制定针对性的检测策略。将利用这些检验策略所检测出的真实情况与分析结论进行对比,最终验证了RBI技术在延期服役平台静设备风险评估方面具有很强的适用性。     

Calibrate failure-based risk assessments to take into account the type of chemical processed in equipment

Currently, failure-based risk assessments in the process industry do not empirically take into account the type of chemicals processed in equipment, mainly because chemical-specific failure rate data barely exist. This paper suggests a methodology to calibrate failure-based risk assessment predicated on the chemical being processed in equipment. The methodology uses a data mining tool known as the association rule. Specifically, the lift association rule is utilized (the Lift Methodology). By extracting equipment failure information from incident databases based on the chemical involved in the process, the Lift Methodology leads to more accurate equipment-related risk assessment.     

Risk-based maintenance (RBM): a quantitative approach for maintenance/inspection scheduling and planning

The overall objective of the maintenance process is to increase the profitability of the operation and optimize the total life cycle cost without compromising safety or environmental issues. Risk assessment integrates reliability with safety and environmental issues and therefore can be used as a decision tool for preventive maintenance planning. Maintenance planning based on risk analysis minimizes the probability of system failure and its consequences (related to safety, economic, and environment). It helps management in making correct decisions concerning investment in maintenance or related field. This will, in turn, result in better asset and capital utilization.

This paper presents a new methodology for risk-based maintenance. The proposed methodology is comprehensive and quantitative. It comprises three main modules: risk estimation module, risk evaluation module, and maintenance planning module. Details of the three modules are given. A case study, which exemplifies the use of methodology to a heating, ventilation and air-conditioning (HVAC) system, is also discussed.     

Improvement of integrity management for pressure vessels based on risk assessment - A natural gas separator case study

The process of oil and gas processing plant is complex, the types of pressure vessels are rich, and the functions are critical. However, the working medium is mostly untreated medium, and the hazard factors are complex, which poses a threat to the safe production of oil and gas processing plant. Based on PDCA cycle, this paper establishes a six-step links of integrity management for sustainable improvement of pressure vessels. The typical failure modes of pressure vessels are determined, and the fishbone diagram of risk factors under each failure mode is compiled. Risk quantification and classification of pressure vessels based on failure modes (RBFM) is innovatively proposed. Avoiding incalculable failure frequency index, the process quantification of failure possibility is formed according to the development of hazard factors. A failure consequence calculation model based on the leakage affected area was established. Combined with the failure probability level and risk level, the hierarchical inspection strategy for pressure vessels under different failure modes is established. Finally, the method is applied to the natural gas separator of H processing plant. The research results show that RBFM proposed in this paper can meet the requirements for rapid and accurate risk assessment of pressure vessels in oil and gas processing plant. This paper establishes a safe production barrier for the pressure vessel and improves the intrinsic safety of the equipment.     

Safety-based process plant layout using genetic algorithm

This paper presents a method based on a genetic algorithm for optimizing process plant layout. The relative location of main process units is determined to minimize an annual cost function including the cost of material transfer between process units (piping and pumping costs), land cost, and the expected annual loss resulting from damage to each secondary unit caused by primary accidents occurring in nearby process units. This method is an improvement over previous attempts using genetic algorithms or mathematical programming techniques to optimize plant layout, which neglected pumping costs and included safety issues by evaluating the infringement of predefined safety distances only. In this approach the operating cost of material transfer is included and the likelihood of accidents is taken into account thus providing good practical solutions to the plant layout problem incorporating more realistic cost functions and constraints. In the paper, after discussing the structure of the annual cost function and describing the working logic of the layout generating algorithm, a case study is described to demonstrate the effectiveness of the proposed methodology.