SIL analysis of subsea control system components based on a typical OREDA database

Proper performance evaluation of subsea system components is of high significance for reliable operation and remote monitoring or the replacement of the components before the occurrence of any failure. As a part of subsea systems, subsea control system (SCS) plays a key role in accomplishing a reliable performance. Hence, achieving knowledge of the components’ failure rates is highly important in the safety analysis of SCS. To the author's knowledge, limited work is done on the safety analysis of SCS using failure rates for a multitude of components. Also, the number of research papers that are based on industrial works is restricted. Hence, this paper aims to provide a noticeable contribution in fulfilling the referred gap. For this purpose, a safety integrity-level (SIL) analysis is proposed based on a typical OREDA database. In the implementation of the proposed SIL, a failure mode classification table is provided for a selection of SCS components. This is followed by the estimation of several parameters, such as the total time in service, as well as obtaining the values of critical failure rates. The analysis indicates that signal failure is the failure mode occurring more than the other ones. Also, the subsea electronic module yields the highest value of critical failure rates. Besides, a comparison of parameter values is provided for two different versions of the utilized database.     

Spurious activation of safety instrumented systems in the oil and gas industry: Basic concepts and formulas

Spurious activation of safety instrumented systems in the oil and gas industry may lead to production loss, stress on affected components and systems, and hazards during system restoration. This article defines and clarifies concepts related to spurious activation. A clear distinction is made between spurious operation, spurious trip, and spurious shutdown. The causes and effects of spurious activation are discussed and related to the concepts used in IEC 61508, IEC 61511, and OREDA. A new set of formulas for calculating the spurious activation rate is presented, and compared with formulas that are frequently used in the oil and gas industry. The new approach is illustrated in a simple case study.     

通用弹药失效辅助分析数据库的设计与研究

主要设计了用于弹药失效分析系统的数据库,着重描述了数据库的逻辑设计.通过故障模式、影响及危害度分析方法总结了对弹药进行失效辅助分析所用的基本数据,建立了各个数据之间的逻辑关系.在现有资料基础上收集了通用弹药的失效模式、失效机制、失效案例等数据.该数据库的建立能够为从事弹药失效分析工作的人员提供相关信息并提供操作上的方便.     

A synergetic approach for assessing and improving equipment performance in offshore industry based on dependability

The objective of this paper is to present a framework for assessing and improving offshore equipment performance based on dependability. The main idea is to employ principle component analysis (PCA) and importance analysis (IA) to provide insight on the equipment performance. The validity of the model is verified and validated by data envelopment analysis (DEA). Furthermore, a non-parametric correlation method, namely, Spearman correlation experiment shows a high level of correlation between the findings of PCA and DEA. The equipment of offshore industries is considered according to OREDA classification. The approach identifies the critical equipment, which could initiate the major hazards in the system. At first PCA is used for assessing the performance of the equipment and ranking them. IA is then performed for the worst equipment which could have most impact on the overall system effectiveness to classify their components based on the component criticality measures (CCM). The analysis of the classified components can ferret out the leading causes and common-cause events to pave a way toward decreasing failure interdependency and magnitude of incidents which ultimately maximize overall operational effectiveness.     

机电装备失效分析预测预防进展——失效学体系的形成和发展(一)

初步回顾和总结近十年来,我国在机电装备失效分析预测预防实践和学术方面的重大进展——失效学体系的形成和发展情况;对失效分析诊断、失效预测和失效预防的理论、技术和方法等三个子体系进行归纳、分析、整理,阐述失效学体系的初步构成和基本内涵.     

The analysis of failure data in the presence of critical and degraded failures

Reported failures are often classified into severityclasses, e.g., as critical or degraded. The critical failures correspond to loss of function(s) and are those of main concern. The rate of critical failures is usually estimated by the number of observed critical failures divided by the exposure time, thus ignoring the observed degraded failures. In the present paper failure data are analyzed, applying an alternative estimate for the critical failure rate, also taking the number of observed degraded failures into account. The model includes two alternative failure mechanisms, one being of the shock type, immediately leading to a critical failure, another resulting in a gradual deterioration, leading to a degraded failure before the critical failure occurs. Failure data on safety valves from the OREDA (Offshore REliability DAta) data base are analyzed using this model. The estimate for the critical failure rate is obtained and compared with the standard estimate.     

The failure intensity process and the formulation of reliability and maintenance models

A unified approach to the formulation of failure event models is presented. This provides a common framework for the analysis of both repairable and nonrepairable items, preventive as well as corrective maintenance, and it also applies for items with dormant failures. The suggested procedure is supported by a set of graphs, thereby identifying the significance both of the inherent reliability (i.e., hazard rate) and of the maintenance/repair policy. The definition/interpretation of various failure intensity concepts is fundamental for this approach. Thus, interrelations between these intensities are reviewed, thereby also contributing to a clarification of these concepts. The most basic of these; concepts, the failure intensity process, is used in counting processes (Martingales), and is the rate of failures at time t, given the history of the item up to that time. The suggested approach is illustrated by considering some standard reliability and maintenance models.     

Hybrid expert system for the failure analysis of mechanical elements

An expert system for the failure analysis of metallic mechanical components is described, with emphasis on the structure and the solution strategy followed by the software. The system treats failure in common mechanical elements and is aimed to guide non-experts through the process of basic failure analysis. The system acts as a “virtual colleague”, providing guidance and experience during failure studies. As such, it allows the users to gradually increase their experience while using the software in distinct applications. The system works interactively through a system of structured questions. The answers provided by the user permit the software to direct the analysis toward its solution. Decisions are taken in a hybrid way, through case based reasoning and rule based reasoning, the former using a database of solved cases, the latter mimicking the way experts treat failure analysis. The paper describes the development method, the logic behind the operation of the system and the interaction between case based reasoning and rule based reasoning modules. Its performance in four real-world failure cases is used to demonstrate its feasibility and usefulness.     

混凝土结构耐久性预估研究进展

混凝土结构耐久性问题日益重要,在总结结构耐久性评估和剩余寿命预测方法基础上,提出了混凝土结构耐久性预估需要解决的一些基本问题,包括失效准则、专家数据库、耐久性指数和全寿命周期分析,认为混凝土结构耐久性研究应充分考虑材料发展,并且混凝土材料的渗透模型或Cr扩散模型是关键问题,强调急需建立耐久性设计方法.     

印刷机模拟操作软件研究

针对印刷模拟操作软件的基础部分进行了研究,主要包括印刷故障分析及调整等。选取单张纸胶印机为例,从纸病分析、纸路故障到墨路故障以及其他故障着手,进行了分类总结,在此基础上,利用Access软件建立了印刷故障数据库,并利用VB软件进行了人机交互平台的开发。     

桥梁电子化人工巡检养护管理系统

将危险性分析与量化管理理念应用于桥梁电子化人工巡检养护管理系统的总体设计中,为大型桥梁量身定制巡检养护规划,规范桥梁巡检养护流程,编制巡检养护手册,用于指导巡检养护工作的实施;针对桥梁结构的具体特点,建立专门结构的损伤库,编制电子化人工巡检养护软件,实现巡检养护管理工作的电子化。     

Loss of safety assessment and the IEC 61508 standard

The standard IEC 61508 contains a lot of useful information and guidance for safety improvement regarding the use of safety systems. However, some of the basic concepts and methods for loss of safety quantification are somewhat confusing. This paper discusses the failure classification, the various contributions to the safety unavailability, and in particular the common cause failure (CCF) model presented in this standard. Suggestions for clarifications and improvements are provided. In particular, a new CCF model is suggested, denoted the Multiple Beta Factor model.     

Bayesian networks inference algorithm to implement Dempster Shafer theory in reliability analysis

This paper deals with the use of Bayesian networks to compute system reliability. The reliability analysis problem is described and the usual methods for quantitative reliability analysis are presented within a case study. Some drawbacks that justify the use of Bayesian networks are identified. The basic concepts of the Bayesian networks application to reliability analysis are introduced and a model to compute the reliability for the case study is presented. Dempster Shafer theory to treat epistemic uncertainty in reliability analysis is then discussed and its basic concepts that can be applied thanks to the Bayesian network inference algorithm are introduced. Finally, it is shown, with a numerical example, how Bayesian networks’ inference algorithms compute complex system reliability and what the Dempster Shafer theory can provide to reliability analysis.     

机械制造企业失效分析数据库的开发及应用

针对笔者公司目前失效分析工作中存在的问题，开发了失效分析数据库，并在企业中进行了应用。失效分析数据库在失效分析案例文字和图片的保存、失效分析案例的查询和统计、同类失效件失效原因的归纳总结、失效分析人员经验的积累、零件生产环节质量的监控和管理等方面发挥了重要作用。     

Steel hardenability and failure analysis

Hardenability evaluation is typically applied to heat treatment process control, but can also augment standard metallurgical failure analysis techniques for steel components. A comprehensive understanding of steel hardenability is an essential complement to the skills of the metallurgical failure analyst. The empirical information supplied by hardenability analysis can provide additional processing and service insight to the investigator. The intent of this paper is to describe some applications of steel thermal response concepts in failure analysis, and several case studies are included to illustrate these applications.     

选材系统的设计与实现

介绍一个基于材料科学数据库的选材系统。该系统按照开放性的原则设计，将材料科学数据分为三大部分：仅与材料成分有关的基本材料数据，材料加工和应用过程中产生的材料加工工艺和性能数据，材料产品的生产供应等商业信息。     

Failure Analysis and Life Assessment of Coating: The Use of Mixed Mode Stress Intensity Factors in Coating and Other Surface Engineering Life Assessment

Unlike metals, where failure analysis and life assessment methods are quite established, the failure analysis and life assessment of coatings are often underrated and disregarded. This research encourages failure analysts to realize and avail the opportunity provided by an alternative approach. The authors use energy density mechanics concepts to develop a new parameter in coating blistering. A mixed mode stress intensity factor is used as a basis for the derivation. This new parameter will be useful for the researchers and practitioners engaged in coating life assessment. It is recommended that the assessor combines field-determined adhesion strength values and blister evaluation, together with laboratory-derived strain energy density data, to quantitatively predict remaining coating life. This approach also provides a tool in failure analysis.     

Practical experience with a data collection project: the OREDA project

Experience data on the reliability of equipment has become vital to many types of engineering and maintenance analyses. The consequences of incorrect design or poor maintenance may adversely affect: safety, the environment or cost in most categories of process industries, and, in particular, offshore exploration and production industries. The OREDA project is a data collection programme for the offshore industry which has been operating since the early 80's. A high level of knowledge has been gained from this programme on: specification of data, data collection methods and the utilization of data. Some of the results and the knowledge gained from this project are presented in this paper.     

Damage due to hydrogen embrittlement and stress corrosion cracking

Damage of metals due to the influence of hydrogen and to stress corrosion cracking is quite frequent and leads to dangerous failures as well as to loss of property and large compensational payments by insurance companies. One reason for this, is that some designers and engineers seem to lack sufficient knowledge of the basic mechanisms of these phenomena and accordingly often have only vague ideas how to prevent such failure causes. Although the basic concepts can be found in a number of good text books it seems worthwile to recall them in a short comprehensive paper.     

失效分析技术

简要介绍了失效分析技术——痕迹分析技术、裂纹分析技术和断口分析技术等的基本概念、主要内容、一般程序和基本方法，以及它们在工程失效分析中的应用。