[0:14]Hello everyone. Welcome to industrial safety engineering. Today we will discuss key concepts and terminologies. Let us first see the contents. I'll explain some of the terminologies related to safety engineering. Then, hazard theory, followed by hazard triangle, different causal factors, hazard recognition. This lecture is primarily based on the book, Hazard Analysis Techniques for System Safety, written by A. Ericsson II Clifton, published by Willey.
[1:00]So, as you know that safety engineering is a interdisciplinary subject. is taken or borrowed knowledge from different disciplines and over the years, it matured and it has its own vocabulary or language. And knowing safety engineering or being expert in safety engineering, essentially also includes that you know the language of safety engineering. In today's lecture, I want to explain those vocabularies and the definition in such a manner that you you spell out or speak about all those terms and terminologies in that manner. And then it will be understood that you have gone through this course, you have knowledge on safety engineering at the first instance. So, under terminologies, the first one is first one is your safety. So, if you go through dictionary, you will find this definition, being safe, freedom from risk or danger (dictionary). But a better definition could be degree of freedom from harm or danger. So, the basic premises behind this definition, under industrial safety or as such under safety engineering, every activity, whatever you do, that contains some amount of danger or risk or harm. So, as a result, 100% harm the that the hazard-free operation is difficult to have. So, by safety we want to mean, when you do some activities or you work somewhere, then what is the freedom you enjoy from harm or danger? So, that's why that freedom is degree of freedom.
[4:04]Okay. For example, if you are working in a control room, AC control room, and you are working near blast furnace, or you are you are you are operating a machine in works in shop floor,
[4:30]or a person who is driving a car or someone who is basically launching that missile, or or somebody who is basically cooking in the kitchen. So, you find out that they do not expose to same amount of danger or risk. There is degree of difference. So, that degree of freedom is safety. So, we will stick to this definition, degree of freedom. When we talk about safety, essentially, we also talk about risk. Because the safety and risk, they are very much related terminology, when safety is degree of freedom from harm or danger, risk is perhaps the measure of that harm or danger. So, if you go by dictionary definition, you find out that the this is hazard, peril, jeopardy (dictionary), these many things are common common man definition of risk. But from safety engineering point of view, the definition what we want to follow is this. It's an expression of the impact and possibility of a mishap in terms of potential mishap severity and probability of occurrence. I'll explain later on when we discuss about risk assessment or risk quantification, in in a better manner. I can say that better meaning means in more objective manner. But for the time being, risk is basically a a quantification. It's the quantification of hazard potential. I'll explain hazard little later. So, it is basically mishap in terms of severity, that is important word, and another one is probability. So, risk, if it, risk is R, then this is probability of occurrence, some undesired event, times consequence or severity of that undesired event.
[7:22]So, this is our most traditional definition of risk. So, we will basically follow the second definition, not the dictionary common man definition. The safety engineer definition is the second one. And we'll elaborate in detail on risk. The third term terminology, which is accident. So, accident, an undesirable and unexpected event, a mishap, an unfortunate chance or event (dictionary). We will not follow this dictionary definition. We will follow definition given by some standard authority. Where accident are mishap, accident is a mishap happening. So, that will define. When I define mishap happening that time again I will define accident. For the time being, you think of that someone working at high, there is a chance that he will fall. So, fall of fall from height. Worker working in a material year, there can be there can be possibility that he will be hit by moving machines. Hit by objects. So, these are all accidents. So, so accident is unfortunate, undesirable event. Okay. So, then few more definition.
[9:18]Incident. For incident and accident there is similarity as well as dissimilarity. Incident here anything what is basically may be desirable, may be undesirable, but we will basically talk about undesirable incident. And and it is it it can be of any severity, any consequence, without consequence, without severity, that is incident. But when you talk about accident, the severity or consequence is bigger, larger than incident. But anyhow, incident measurement is an important important or incident management is an important issue. Let us differentiate between incident and accident. Suppose, I said that, working at the shop floor, sometimes the worker may fall on the same floor. Or may what may happen that about to sleep, while about to sleep is incident. But fall at the floor level that is accident. Okay.
[10:50]So, an accident is an incident, but an incident may not be accident. But nowadays, this definition there is very, very less differentiations. Or that I can say the less differences. Okay. I told you about mishap, which is nothing but accident. But here the dictionary definition is unfortunate accident. We will not stick to this. We will stick to the second definition given by military standard 882D report. It is an unplanned event or series of events resulting in death, injury, occupational illness, damage to or loss of equipment or property, or damage to the environment. Carefully observe that it is unplanned event or series of events. What it will do? It will do death, it may lead to death, it may lead to injury, it may lead to occupational illness. These all related to personnel.
[12:03]Then damage to or loss of equipment and property, it is related to property. Then damage to environment. Third one is environment. So, there been an accident or mishap lead to damage for personal, for property, for environment, individually or collectively, or in combination.
[12:41]And mishap and accidents are synonymous for us. Mishap and accidents are events. These are unfortunate events. These are random events. Okay. So, many we say accident two types. One is basically man-made, another one is the chance event. So, whatever may be the reason that we will discuss later on. But for the time being you please stick to this definition. It is an unplanned event or series of events resulting in death, injury, occupational illness, damage to or loss of equipment to property and environment damage. Okay.
[13:29]Then another important definition for us is hazard. Very important definition hazard. Hazard, if you go by dictionary, see, it is basically to risk, to put in danger or loss of injury. But safety engineer definition should be like this. Any real and potential condition, real or potential condition. That can cause injury, illness or death to personnel, damage to or loss of a system equipment or property or damage to the environment. Both coming from military standard 882D. If you see the difference between the two definitions, then you see in the first definition, when you are talking about accident or mishap, we are saying an unplanned event or series of events, resulting into loss to person, property or environment. When you are talking about hazard, we are talking about any real or potential condition. Accident, event which is realized. Hazard, condition, which is not realized. But it can lead to accident. So, the difference between the two the difference between the two in the in the one is realized, another one is not realized. Hazard is potential, and accident or mishap is the event which is already occurred. But the rest of the thing in this different two definitions, like after resulting in death, injury, illness, all those property damage, environment damage, and in the second case also the potential condition that can lead to lead to loss to personnel, property and environment. So, that's why carefully observe the two definition and you see that apart except this first part, the result the series of events, this after here and here any real or potential condition. This this is the difference. Rest of the things are same hidden. Okay. So, that means accident and hazard, they are the two they are the two sides of a coin. So, one side is potential condition, another side is realization of that potential condition in terms of undesired events leading to loss to property, loss to personnel, environment, of different degrees of freedom or degrees of risk.
[16:35]Okay.
[16:38]So, we'll go with some example now that we will basically see that what is the accident and hazard. As I told you that accident and hazard are the two sides of a coin. So, as a result the theory says that that hazard will ultimately converted to accident. Hazard to accident. So, I am I am giving huge importance to these two words, hazard and mishap. The reason is that if you if you know what is an hazard and accordingly, identify hazard in the workplace or the system for which you are concerned about for which the safety is an issue, then identification of hazard is very, very important one and you know that once you ident know the hazard, then it is possible to to combat with the hazard. So, now, a safety engineer wants to know that if given the hazard, what way it will ultimately lead to actual consequences that means accidents. So, hazard is before state potential condition, and accident is after state actual consequences. This hazard is is converted to accident and that is known as state transition. That mean hazard is a state, and accident is another state. So, there is state transition for any system, for any workplace, for any job. With reference to hazard theory, how the hazard a state is converted to the accident state you have to identify, you have to know, you have to find out the path. So, that that transition path, if you know how a hazard will ultimately lead to an accident and accordingly the path is known, path is known, then much work is completed. So, that means by hazard theory, what do we mean? We mean that hazard is a potential condition for accident. Now, how this potential condition ultimately lead to accident, knowing the path is the job of safety engineer. And accordingly, putting intervention or barriers in between in such a manner that that path will not realize. So, that is what is basically hazard theory. Now I will give you one example, that what do you mean by what is the difference in terms of hazard and accident. You see the example, worker could be electrocuted by touching exposed contacts in electrical panel containing high voltage, in electrical panel containing high voltage. Worker could be electrocuted. So, what is very important, could be electrocuted. So, that mean this is the potential case. What is accident? Worker was electrocuted. Okay. So, worker could be electrocuted and worker was electrocuted, that is the difference. Could be electrocuted is a condition and was electrocuted is a event. And then, what way it has happened? By touching exposed contacts in electrical panel containing high voltage. So, there is no difference here also, by touching exposed contact in electrical panel containing high voltage. So, this is the transition, that worker could be electrocuted condition, you must know and accordingly you put barrier so that it will not happen. But if you do not do anything, what will happen? This will ultimately realize into accident. Safety engineer must understand that how this potential state will converted to accident state, this transition. I am repeating the word, transition. Okay. And you see, apart from this, that hazard and accident accident or mishap.
[21:37]Accident or mishap. There is another quantity called Hazard-mishap entity. What is this? This is nothing but measure of hazard potential. Okay. That means what we mean to say. What is the amount of hazard that that is involved in this particular job, particular work. So, this is what is also known as risk. This is what is known as risk. Okay. So, from hazard theory point of view, hazard-mishap entity is a important concept, which is basically risk.
[22:38]Okay. So, that been what we have learned? We have seen some definitions, particularly common definitions, what a safety engineer should know. Hazard, accident, risk, then incident, and safety. What is the definition of safety?
[23:03]And then we have found that hazard and accident are two sides of a coin, and a safety engineer must know how the hazard state is converted to an accident state. It is the job of a safety engineer. So, you first know how hazard will be converted into accident, and what is the path, which path it should follow? There can be multiple paths.
[23:39]So, one very important concept that is that the hazard theory, that state transition from hazard state to accident state. Okay.
[30:19]So, I will repeat this important concept, that hazard components. Hazardous elements, this is the basic hazardous resource creating the impetus for the hazard, such as a hazardous energy source such as explosives being used in the system.
[30:45]Initiating mechanism. This is the trigger or initiator events causing the hazard to occur. The IM causes actualization or transformation of the hazard from a dormant state to an active mishap state.
[31:21]Target and threat. This is the person or thing that is vulnerable to injury and/or damage, and it describes the severity of the mishap event. This is the mishap outcome and the expected consequential damage and loss.
[34:51]Here, it's basically for describing how to write properly the hazards.
[35:06]In there are poor example and good examples. Suppose, many a times what happen? Based on my experience I have seen that when I have I have seen some accident report or in inspection report, people have written repair technician slips on oil.
[35:28]So, this kind of this kind of write-up is not good. This kind of write-up is not good example of hazard, poor example of hazard. Or signal MG71 occurs. Or person fall from falls from working platform. Now, good example will be overhead valve V21 leaks oil on walkway below, spill is not cleaned. Repair technician walking in area, slips on oil and falls on concrete floor, causing serious injury.
[36:06]You just read all those things. What happened? You will find out that in this particular example, the hazardous element, initiating mechanisms and targets and threats are clearly written. And after after reading this, you will be able to find out that the sequence of events. Similarly, here also suppose person falls from from working platform, working platform for plastering work was made without toe guard. And workmen were not using safety belt, end of railing pipe was also not tied properly. Person fall from working platform causing serious injury.
[36:47]Here working platform at height, that is basically the hazardous element. And what are what are the initiating mechanisms? It was not having toe guard. And workmen were not using in safety belt. Then also the railing pipe was not tied properly. So, these three things, three initiating mechanisms, ultimately lead to person fall from from the working platform. And what is the threat? Here the threat was basically that he or she she basically experience serious injury. Okay. So, this is basically the way you must write hazard. By hazard, I mean to say that there are three component. One is your, one is your hazardous elements, which is basically the resource, like hazardous energy source.
[39:15]And initiating mechanisms, these are the basically series of events that can take place, ultimately leading to leading to that accident. An accident basically puts threat to the targets. Targets are people, property and environment. A design flow can be a mishap waiting to happen. Suppose, you design a process. Okay. Suppose, a boiler you design. And and there there is a flow. So, suppose a important sensor safety point of view you fail to install there. What will happen? Anytime an accident will happen. Okay. So, design flow is very, very important one. So, that's why we say that safety engineering, engineers basically do design. So, safety engineering, it should start at from the at the design house. It should it should be it should be in the at the extreme upstream of a system life cycle. A hazard will occur according to hazard components involved. Obviously, depending on the hazard components. A hazard is deterministic entity, not a random event. Understand, accident is a random event. But hazard is not a random event. It's known. If you do not know what are the hazards at your plant, that means you are ignorant about the system. You don't have design knowledge. You don't have system knowledge. Means adequate design and system knowledge. Means adequate design and system knowledge. Hazards and mishaps are predictable. Therefore, are preventable or controllable. Obviously, as hazard is deterministic, it is predictable. Mishaps, even though random, they are also predictable. And if something can be predicted, it can be prevented or controlled. Okay. So, this is for today. I hope that I have give I have given you the theoretical side of hazard and and the issues the means the components of hazards. And and and how you can equate hazard and accident. If you know hazard, you know accident. And it is you, the design engineer, the safety engineer, who will build a system in such a manner that it will be minimum hazard prone. Or minimum hazard will be in built. Because that is required for the production operation or other functionalities point of view. But that minimum hazard also should not be kept unattended.
