Method for identifying errors in chemical process development and design base on accidents knowledge

It has been claimed that the high accident rate in the chemical process industry is due to poor dissemination of accident knowledge that affects directly the level of learning from accidents. In response to this situation, this paper utilized past accident knowledge as a basis to develop a safety oriented design tool whereby the accident information were directly disseminated into plant design. The method was developed based on our previous accident analysis of design error in which the common design errors were ranked in accordance to their frequency and its origins during normal plant design project. Based on the design error ranking and its origin at a specific design phases, a method for design error detection is proposed. The method is expected to be able to identify the possible design error and its causes throughout chemical process development and design. The main objective is to trigger safe design thinking at the specific design phases so that appropriate action for risk reduction could be timely implemented. The Bhopal and BP Texas tragedies are used as case studies to test and verify the method. The proposed method can detect up to 74% of design errors.     

Method for identifying contributors to chemical process accidents

The paper presents a new method for identifying contributors to chemical process accidents by exploiting knowledge on causes of past accident cases. Accident reports from the Failure Knowledge Database were analyzed and utilized for hazard identification. The accident information gathered was used as a basis to develop an accidents ranking and points-to-look-for approach for the safe design and operation of chemical process equipment. In the method, accident contributors including technical, design and operation errors of major process equipment types and piping are identified. The method is applicable throughout the process lifecycle, even for process changes in the early design stages. The Bhopal tragedy is used as a case study to demonstrate and test the method. The proposed method can predict on average up to 85% of accident causes and design and operation errors.     

Origin of equipment design and operation errors

The paper discusses the origin of chemical process equipment accidents by analyzing past accident cases available in the Failure Knowledge Database (FKD). The design and operation errors of the process equipment that caused the accidents were analyzed together with their time of occurrence. It was found that design errors contributed to 79% of accidents while the rest were only due to human and organizational errors in the operation stage and external factors. The most common types of errors were related to layout, organizational errors in the operation stage, considerations of reactivity and incompatibility, and wrongly selected process conditions (each approx. 13% of total accident contributors). On average there were about 2 design errors per accident. The timing of the errors was quite evenly distributed between various lifecycle stages. Nearly half (47%) of the errors were made in process design-oriented stages, one fourth (26%) in detailed engineering, and one fifth (20%) in operation. In addition, the most frequent design and operation errors for each equipment type were identified. A points-to-look-for list was created for each equipment type, showing also the typical time of occurrence of the error. The knowledge of type and timing of design errors can be utilized in design to focus the hazard analysis in each stage on the most error-prone features of design.     

Design as a contributor to chemical process accidents

The paper discusses the design errors in chemical process industry (CPI) by analyzing major equipment related accident cases from Failure Knowledge Database (FKD). The aim is to recognize the contribution of design to chemical process accidents and to evaluate the time of occurrence of the errors in a plant design project. The analysis of accident cases found out that the contribution of design to accidents is very significant: 79% of accident cases analyzed were contributed by design errors. The most critical design errors were poor layout (17%), insufficient consideration of chemical reactivity and incompatibility (16%) and incorrectly chosen process conditions (16%). The design errors were initiated at basic (32%), detailed (32%) and preliminary (22%) design phases of the project. Errors in fundamental aspects of chemical processes e.g. route selections are more severe (as compared to others errors class) and might creates many similar errors in later phases of design project. Based on the accident information gathered, a straightforward point-to-look list for error detection and elimination was suggested for process lifecycle stages.     

Near-miss management systems: A methodological comparison

A close relationship between near-miss events and major accidents has been demonstrated in major hazard facilities: a near-miss and an accident have often common causes. A near-miss could be defined as a hazardous condition where the event sequence could lead to an accident if it had not been interrupted. An effective Near-miss Management System (NMS) aims to quickly recognize signals from the operational fields in order to apply prevention strategies. As a standard reference model has not yet been developed, the NMS design represents a complex issue. The present paper proposes a critical comparison between two methodologies which could be applied for a near-miss event assessment: a matrix and an index based method. The purpose is to evaluate potentiality and pitfalls of their application as their global efficiency could influence the whole performance of the whole NMS design. An application in a test case of a chemical plant is proposed: results obtained have proved useful in supporting safety management in an effective design of a NMS.     

A novel chemical product design framework with the integration of safety and health aspects

Computer-aided molecular design (CAMD) technique is a powerful tool for the design of molecules that meet a set of desirable properties. In most of the CAMD problems, the molecular physical and thermodynamic properties are often selected as the target properties, while safety and health aspects were not taken into consideration. However, certain chemical substances may cause adverse effects to human's health after prolonged and repeated exposure. Therefore, in order to ensure that the generated molecule does not bring harm and health-related risks to the consumers, it is crucial to incorporate both inherent safety and health into the existing CAMD techniques. In this work, a novel chemical product design methodology has been developed to integrate both safety and health aspects into the CAMD framework presented by a single optimisation model. The measurement of safety and health indicators are based on the molecular properties that have impact on both of these aspects. Each property is assigned with an index or penalty value based on the degree of potential hazards. A molecule with a higher index value has a higher hazard level and vice versa. Hence, a molecule that satisfies the target properties and has a low penalty value will be selected as the most reasonable choice. This new approach ensures that a product that possesses the desirable properties, and at the same time meets the safety and health criteria, is produced. A case study on the solvent design for gas sweetening process has been carried out to determine the optimal molecule.     

Inherently safer design review and their timing during chemical process development and design

This paper discusses the enhancement of inherent safety review and its implementation in the chemical process development and design. The aim is to update and improve the existing inherently safer design review (ISDR) practices during design of chemical process plant by exploiting major accident cases from the U.S. Chemical Safety Board (CSB) and Failure Knowledge Database (FKD). Although the basic guidelines to conduct ISDR during design phase are available, however they are too general and incomplete. The review criteria and their best timing for application are still missing. This paper attempts to develop the accident-based ISDR for chemical process plant design. The proposed accident-based ISDR is supported with detail review criteria for each phase of process design. The timing of ISDR application is corresponding to the common design tasks and decisions made in the design project. Therefore, timely design review could be done at the specific design task and the findings help designer to make a correct decision making.     

A new intelligent assistant system for HAZOP analysis of complex process plant

There are several problems that should be solved in the practical application of HAZOP analysis, such as the inheritance instrument of experience knowledge, the classification of accident reasons, the recurrence of analysis process and the verification of analysis results. This paper presents a new HAZOP assistant program named HELPHAZOP, which can be used to cope with these problems. With the aid of this program, a number of influence relationship models, which can be utilized to present the relationship structure of the whole system, can be established, and a variety of spread paths, which can be employed to describe the occurrence of the accidents, can be identified. These models and paths can help analyzers to understand the analysis process of different chemical processes and to verify the analysis results. Experience knowledge or information of process parameters stored in this program, including deviations, abnormal reasons, consequences and disaster-causing ways, can contribute to the analysis of some new plants. The program has been applied in the HAZOP analysis process of residuum hydrotreating process. The probability of the human errors which would be happened because of the misunderstanding or the deficiency of plant experience in the HAZOP analysis has been reduced and the accuracy, practicability and analysis efficiency of the accident forecast have been greatly improved.     

The post-Bhopal and post-9/11 transformations in chemical emergency prevention and response policy in the United States

The United States' approach to incident prevention and response to hazardous chemical facilities has undergone two major transformations in the last 20 years. The first was triggered by the Bhopal tragedy in 1984, which led to major changes within the US chemical industry and a series of Federal laws and regulations intended to prevent major chemical accidents. A more recent transformation is currently underway in the wake of the 9/11 attacks on New York and Washington. It involves the advent of various security-related requirements affecting many of the same facilities covered under the existing accident prevention rules. This paper provides an overview of these transformations and their impacts.     

Economic assessment of human errors in manufacturing environment

Traditional human reliability assessment techniques and accounting system cannot directly provide loss information for assessing the impacts of human errors. This obstacles force industrial managers to justify the proper accident and injury prevention process through their experiences. The efficiency and effectiveness of the system safety barriers are in doubt and the smooth operation of manufacturing activities are insecure. In this study, a human error cost estimation model is introduced to facilitate line managers with a proper tool to collect and calculate the total losses of its impact. Experts’ judgments and pair wise comparison technique are incorporated to interrogate managers’ knowledge of human errors and correspondent costs. This approach can overcome the problem of insufficient cost information caused by current accounting system and compensate the influence of safety and health department due to the low organizational status in quo. Although the cost figures may not represent exact amount of losses, the percentage of each cost factor in terms of department operation budget gives the managers a practical way for justifying how the resources should be allocated.     

An approach for determining the extent of contribution of construction project features to accident causation

In the pursuit of Health and Safety (H&S) improvement within the UK construction industry, several studies have been conducted to identify accident causal factors to enable the development of accident prevention measures. Adding to such studies, a critique of H&S literature demonstrates that construction project features (CPFs) such as the nature of project, method of construction, site restriction, project duration, procurement system, design complexity, level of construction, and subcontracting contribute to accident causation and that their contribution is through the introduction of proximal accident causal factors into the construction process. However, the extent of this contribution by these CPFs remains sparingly known and requires further investigation. The study provides this insight by indicating that the extent to which CPFs contribute to accident causation is influenced by two factors; the extent to which the proximal factors contribute to accident causation; and the extent to which the proximal factors are prevalent within the CPFs. In line with this fresh insight, an approach for determining the extent to which CPFs contribute to accident causation is put forth. The approach proposes to use a qualitative–quantitative rating scale to determine the two determinant factors and then combine them using a mathematical formula to obtain the extent to which CPFs contribute to accident causation. By this approach the grey areas in literature concerning the extent to which CPFs contribute to accident causation will be illuminated and by that contribute to improvement in construction accident prevention.     

Why bad things happen to good people

Accidents in the process industries are extensively investigated to determine root causes, for lessons learned, and many times in search of the “guilty”. Accidents are seldom simple and most accidents have human elements that led to or facilitated the accident. Many times the people involved in these accidents, when considered individually on their merit, would be considered “good” people yet “bad things” (accidents) still occur.Human errors can be classified as individual, group, and organizational. Individual human errors have been addressed in a number of studies and papers. Many of these classify human errors and treat them probabilistically or cognitively. Less has been said regarding the individual psychological/sociological response/interaction mechanisms that might contribute to an industrial accident. These elements also contribute to a lack of situational awareness which often plays a large part in human error. Group and organizational interactions/dynamics can also contribute negatively to situational awareness and to the chain of events of an accident. Organization errors, which are typically latent, can also facilitate an accident and are many times people enabled for personal and business vested interests.This paper will discuss the effect of human error at the practical plant level in contributing to accidents in the process industries from individual, group, and organizational perspective. The discussion will include psychological/sociological response/interaction mechanisms that can contribute to situational awareness and human error. It will also discuss how complexity, veracity, and quantity of available information can affect the human decision-making process leading to mistakes.Accidents are seldom simple and most accidents have a number of elements that led to or facilitated the accident. When looking at individual elements probabilistically, multiplying probabilities together, it is hard to see how an accident could have occurred. A common refrain “That’s double jeopardy and we don’t have to consider that” is essentially a qualitative probabilistic analysis. Yet we have cases of triple, quadruple, n-jeopardy occurring to cause accidents. The paper will discuss the superimposition of causes and a similar concept of functional resonance in causing accidents.     

Applications of dust explosion hazard and disaster prevention technology

Powdered materials are widely used in industrial processes, chemical processing, and nanoscience. Because most flammable powders and chemicals are not pure substances, their flammability and self-heating characteristics cannot be accurately identified using safety data sheets. Therefore, site staff can easily underestimate the risks they pose. Flammable dust accidents are frequent and force industrial process managers to pay attention to the characteristics of flammable powders and create inherently safer designs.This study verified that although the flammable powders used by petrochemical plants have been tested, some powders have different minimum ignition energies (MIEs) before and after drying, whereas some of the powders are released of flammable gases. These hazard characteristics are usually neglected, leading to the neglect of preventive parameters for fires and explosions, such as dust particle size specified by NFPA-654, MIE, the minimum ignition temperature of the dust cloud, the minimum ignition temperature of the dust layer, and limiting oxygen concentration. Unless these parameters are fully integrated into process hazard analysis and process safety management, the risks cannot be fully identified, and the reliability of process hazard analysis cannot be improved to facilitate the development of appropriate countermeasures. Preventing the underestimation of process risk severity due to the fire and explosion parameters of unknown flammable dusts and overestimation of existing safety measures is crucial for effective accident prevention.     

性能化设计思想在化工设施布局安全设计中的应用

指令性规范是目前化工设施平面布局安全设计的主要依据,但其在应用中存在着条款僵化、安全理论基础不全面、可拓展性不明确等问题。本文将性能化设计思想引入到化工企业平面布局安全设计中,初步提出了一种包含危险辨识、性能化目标确定、后果评估及安全设施效用评估等主要组成部分的基于性能化设计思想的平面布局安全设计体系。对体系中最重要的部分—性能化目标确定进行了重点分析,将化工设施布局安全设计分为装置内设备之间的位置设计、厂区内装置区之间的位置设计以及厂区与外部单位之间的位置设计三个级别,从工艺关联性等角度对各级别布局设计中事故场景选择及设施可接受受损水平进行分析,并提出了通过匹配事故场景和设施可接受受损水平来确定性能化目标的方法。     

Inherently safer design based on rapid risk analysis

The importance of inherently safer design (ISD) as a strategy to minimize risk of accidents in chemical process industries is being repeatedly stressed in recent years. The increasing number, frequency, and extents of damage caused by such accidents across the world have contributed to this thinking. However even as the need for ISD is being underscored, there are very few reports on precise methods to implement this concept. Significant recent reports are by Berge (1993Berge, 1995)who has suggested a scenariobased design procedure in which construction of accident scenarios in a structured manner is made the basis of ISD. We have been developing and applying the concept of rapid risk analysis ( [Khan & Abbasi, 1995] , [Khan & Abbasi, 1996] , [Khan & Abbasi, 1997a] , [Khan & Abbasi, 1997b] , [Khan & Abbasi, 1998a] and Khan &; Abbasi, 1998b). In this paper we present an approach to ISD utilizing this concept. We believe, as detailed in this paper, that this approach is a significant improvement upon Berge's procedure in terms of ease, speed, and effectiveness.     

Analysis of equipment failures as contributors to chemical process accidents

A database study of chemical process accident cases was carried out. The objective of the study is was to identify the reasons for equipment based accidents. The most frequent accident causing equipment were piping (25%), reactors and storage tanks (both 14%) and process vessels (10% of equipment accidents). The six most accident-prone equipment is process related involve nearly 80% of accidents.78% of equipment accident contributors are technically oriented including design and human/technical interface faults. Purely human and organizational reasons are the most common accident contributors for storage tanks (33%), piping (18%) and heat transfer equipment (16% of causes). For other equipment the technical accident causes are most common.The accident contributors were divided to main and sub-contributors. On average process equipment failures have 2.2 contributors. The contributors, which frequent and act often as main contributors, should be focused. These risky contributors were identified for several equipment types. Also a deeper analysis of the accident causes and their interconnections was made. Based on the analysis a checklist of main risk factors was created for hazard identification on different types of equipment.     

国内外化学事故数据库的发展现状与展望

为完善我国化学事故数据库,充分发挥其在预防事故中的作用,通过研究美国、欧洲和日本等国家化学事故数据库的发展现状及其特点,分析我国化学事故数据库目前存在的问题。研究表明:国外化学事故数据库发展较完善,其数据结构设计较合理,且事故信息全面、准确,事故数量多;而我国化学事故数据库建设还比较落后,存在数据结构设计简单、标准不统一、数据可靠性差,很多事故信息也未能共享等问题。因此,在发展我国化学事故数据库时,应确保事故数据的数量、质量和多样性,重视未遂事故信息的收集,设计合理的数据结构,并实现数据共享,使其为事故原因分析、事故研究、安全评价和安全培训提供数据支持。     

基于HAZOP分析的加氢装置工程设计方法

加氢装置属甲类火灾、爆炸危险生产装置。为了在设计阶段尽可能消除或控制潜在风险,本文总结了多套加氢装置HAZOP分析报告中的设备类别及其分析内容,提出了基于危险与可操作性(HAZOP)分析的加氢装置工程设计方法。在传统工程设计方法的基础上增加了参数敏感性工程设计方法,依据分析报告中的设计建议,利用ASPEN软件计算过程参数变化对目标参数的影响程度,确定参数稳定操作区域;建立了数据库管理界面实现了加氢装置工程安全设计经验知识的有序管理。应用基于HAZOP分析的加氢装置工程设计方法,有助于将安全隐患问题在设计阶段消除或加以控制,可为降低石化装置改造成本和提高装置的安全水平提供方法依据。