HAZARDS AND rISK
APOLOGY FOR LONG GAP AFTER WHICH RETURNING TO BLOG. i COULD NOT AVOID SO MANY REQUESTS SO COULD FIND SOME TIME TO PREPARE THIS BLOG . pARLY TAKEN FROM MY bOOK : pLANT hAZARD ANALYSIS AND SFAETY INSTRUMENTATION SYSTEMS: http://store.elsevier.com/Pla
nt-Hazard-Analysis-and-Safety- Instrumentation-Systems/Swapan -Basu/isbn-9780128037638/ OR GET THE SAME FROM IChemE: https://icheme.myshopify.co m/products/plant-hazard-analys is-and-safety-instrumentation- systems-1st-edition
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DUE BEFORE MID 2018
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hazard Definition and Discussions: In this clause efforts will be made to define hazard. As is seen from the above, Hazard discussed above is with respect to health & occupational Hazard. One thing is clear that exact definition of hazard changes from case to case but main theme behind is the cause that has potential to bring out untoward situation!
1. In general term one can define Hazard as could be any biological, chemical, mechanical, environmental or physical agent has potential to cause harm or damage to humans, other organisms, plant - machinery, asset or the environment in the absence of its control. In other words, Hazard can be considered as a state with a set of conditions of a system which together with other conditions in the environment, or in the environment of the system will lead to an accident. For example H2 leak from a turbo generator, coming in contact with atmospheric air can cause fire/explosion near turbine if it comes in contact fire or locally hot surface, so smoking is prohibited near that place.
2. In terms of industrial plants hazard can be defined as any condition produced by or in the industry that may cause harm to property (plant – machinery, asset), human or environment. As per HSE .gov.uk “A hazard is something (e.g. an object, a property of a substance, a phenomenon or an activity) that can cause adverse effects”.
3. As per Center for chemical Process safety (CCPS) hazard is defined as “An inherent or physical characteristics that have potential for causing damage to people, property or environment, it is the combination of a hazardous material, an operating environment, and certain unplanned event that could result an accident”.
4. As per ISO/IEC 51 or IEC 61508 hazard is defined as “ The potential source of harm”. In IEC 61508 Harm has been defined as physical injury or damage to the health of people either directly, or indirectly as a result of damage to property or to the environment
5. In order to work as a team it is always recommended to identify and record all possible hazards in the plant as well as at the work place. For such work identification it is better to form a team comprising both experienced and fresh people. Experienced people are familiar with the job and will help to identify the hazards, whereas fresh eyes may throw light on new area of hazard. Following are the major points to be covered in hazard identifications (ref: Canadian center for occupational health and safety--CCOHS):
· All aspect of work
· Include all non routine activities (e.g. Maintenance, repair)
· Accident or incident/near miss record
· Look for foreseeable unusual conditions
· Include people “off site” (not regular)
· Include assessment groups for different levels of risk
6. A few terms, normally encountered in connection with Plant hazard system study have been given below:
· Accident: It is an undesired, unplanned (may not be unexpected always) event which will result in specified level of loss (in terms of health, property, production, etc)
· Mishap: It stands for bad luck, misfortune etc. In terms of industry it could be an accident which is associated with uncontrolled release of energy and toxic material exposure.
· Near miss/incident is normally used in good sense meaning an event occurred, but it involved very minor or no loss (in terms of health, property, production, etc)
· Safety: Freedom (or nearly freedom!) from accident/loss
7. Generally hazards are classified broadly as:
· Biological: Viruses, Bacteria, Animal, Plant
· Chemical: Physical chemical toxic property of the chemical
· Ergonomic: Repetitive movement
· Physical : Radiation, Fire
· Psychological: Stress
· Safety: Slipping etc.
8. When various hazards are identified, initially, it is better to study them carefully to assign risk level associated with each of these hazards i.e. to rank them according to their severity. Following are a few guidelines towards such activities (based on CCOHS):
· Product information/manufacturer’s data
· Past experience
· Applicable standards
· Industrial codes and practices
· Health and safety material about hazard
· Information from Govt. or reputed organization
· Test results
· Expertise from Health and safety engineer (HSE)
· Previous hazard reports (accident/near miss/incident) and hazard statistics
· Use any hazard check list is helpful (e.g. EN1050)
· Work environment
· Skill and experience of worker
· Systems being followed
· Range of foreseeable conditions
9. It is practice to identify the hazard control and follow up action as a part of Hazard identification and preliminary hazard analysis (discussed in details in the next chapter). In order to hazard control one has to look for safety interfaces also. So, following points need to form a part of initial hazard study especially for industrial /process plants, so that entire spectrum is well covered:
· Hazardous component identification
· Possible malfunction of equipment, system including software
· Safety interface including software
· Operating condition and environment constraints if any
· Available facilities & support equipment and support system
· Operating procedure, regular test, maintenance diagnostic features,
· Safety related equipment, safe guard items,
· Possible alternate approach if possible & emergency procedure
10. Listed below are some of the sources of Hazard encountered in industry.
· Sources and propagation of stored energy in the form of Chemical, Electrical, & Mechanical
· Mechanical moving parts
· Nuclear radiation
· Biological hazard ( bacterial growth)
· Fire /explosion
· Human error ( e.g. operating error)
· Software error
· Noise of different forms
· Toxic and corrosive liquids and gas
11. Network security threat is another big hazard in modern day’s practice. For example, Supervisory control and data acquisition (SCADA) the vital infrastructure support in major industrial set ups nowadays faces great threat from security threats. Major security threats come on account of
· Control Networking
· Standardization and open systems
· In secured remote connections
· Availability of public information to hackers.
With this knowledge efforts will be made to find what is hazard analysis? Hazard analysis uncovers the hazards exist in the workplace (in this case industrial plant) focusing on the system/project. As discussed above, in hazard analysis risk (defined in next clause) based decisions are taken to develop means to quantify, track, develop mitigation means & control hazards, follow up action, verify effectiveness & communicate.
Risk Definition: As discussed above risk is the likelihood that a hazard can cause actual damage. In this case also efforts will be made to find some good definitions.
1. As per HSE.govt.UK risk can be defined as “A risk is the likelihood that a hazard will actually cause its adverse effects, together with a measure of the effect. It is a two-part concept and you have to have both parts to make sense of it”.
2. According to EPA “EPA considers risk to be the chance of harmful effects to human health or to ecological systems resulting from exposure to an environmental stressor. A Stressor is any physical, chemical or biological entity that can induce an adverse response. Stressors may adversely affect specific natural resources or entire ecosystems including plants and animals as well as the environment with which they interact.”
3. As per ISO guide 73(2009) Risk is the “effect of uncertainty on object.” With associated notes, some of them are:
· Note 1: An effect is a deviation from the expected—positive and /or negative.
· Note 2: Objectives can have different aspects such as financial, health and safety, and environmental goals and can apply at different levels such as strategic, organization-wide project, product, and process.
· Note 3: Risk is often characterized by reference to potential events, consequences, or a combination of these and how they can affect the achievement of objectives.
· Note 4: Risk is often expressed in terms of combination of the consequences of an event (including changes in the circumstance) and associated likelihood of occurrence.
· Note 5: Uncertainty is the state, even partial, of deficiency of information related to, understanding or knowledge of , an event, its consequence, or likelihood.
4. There is also another definition of risk as per ISO /IEC guide 51 / IEC61508 which is rather straight forward. According to these, risk is “the combination of probability of occurrence of harm and the severity of that harm.”
5. Risk can be conceived as a hazard level combined with likelihood of hazard leading to an accident and dependent on latency of exposure. The definition will be clearer when smoker example is considered. All smokers do not suffer from lung cancer but there is high probability of getting exposed to the likelihood. Again the chances are increased for the person smoking more cigarettes. Similarly a person exposed to asbestos dust, will have a chance for Mesothelioma, and higher the exposure more will be chance of getting affected.
Risk discussions: There are two kinds of risks; one is raw (inherent) risks which represent the risk before taking any control or mitigation action. Second category risks are the residual risks i.e. the risks which could be faced after putting in place controls or mitigation actions (ref Fig 1.0-2). From clause 2.3, it has been found that risk is a combination of likelihood of hazard, Severity, exposure time etc. In this discussion same has been brought in to show interference of each factor so that various terms in connection with risk assessment could be explained. Correct way of combining them is normally unknown also parameters of each of them are not known. Through risk assessment and analysis same is determined. Risk components are therefore Severity, Latency (or exposure) period and Likelihood of Hazard occurrence and likelihood hazard leads to an accident. Fig I/2.5-1 shows the four factors and their combination will generate a new risk value.
Fig I/2.5-1 risk component combination
There are a few factors which affect the risk component some of them are:
· Hazard complexity
· New vs old technology replacement
· New technology and their pace of change
Under this clause short discussion on Risk frequency, categorization, assessment, etc shall be highlighted (based on CCOHS, British standard), whereas details for all these are available in subsequent discussions.
1. Risk frequency: This defines the likelihood of the risk i.e. in other words; it stands for the probability of risk. There are a few categories and these are
· Very likely : at least once in six months
· Likely: at least once a year
· Unlikely: may be once in life time
· Very unlikely: May be 1%
Typical examples are shown here. Risk frequency data, release data are available in HSE (UK), OREDA, OGP etc. publications also.
2. Severity: It is loosely used to indicate the impact of risk i.e. consequence. These are slightly harmful (e.g. superficial cut, minor cut etc.), harmful (e.g. burns, serious pains, minor fracture) and extremely harmful (e.g. major fracture, amputation). There are some other ways to categorize also. Such categorizations are listed below:
· Minor : Minor system damage without causing injury
· Major : e.g. low level exposure to personnel, activates public alarm
· Critical: minor injury to personnel, fire or release of chemical to environment
· Catastrophic: major injury, death big leakage (e.g. Bhopal gas leak)
3. Risk level (Based on action and time): The level of risks are often categorized based on the potential (harm refer clause no. 3.1.4 for further discussions with example). The categories are termed as listed below:
· Very Low: These risks are acceptable may not need any action
· Low: No control may be necessary unless these are available at very low cost
· Medium: Suitable considerations shall be there to see if it risk can be lowered- where applicable to a tolerable level within a defined time limit. However due considerations shall be given for the additional cost for risk reduction. Whenever the risk is associated with harmful consequence, it is necessary to make sure that risk reduction controls are properly maintained.
· High: Good amount of effort is applied to reduce risk on an urgent basis within a defined time frame. It is essential to give due considerations towards the choice amongst suspending or restricting the activity or to apply interim control measure till the main risk reduction control is implemented. Whenever the risk is associated with harmful consequence, it is necessary to make sure that risk reduction controls are properly maintained.
· Very high: unacceptable. Substantial improvements in risk reduction control measures are necessary to reduce the risk to the acceptable level. Activities need to be halted until risk reduction control is implemented. Otherwise, work shall remain prohibited.
· Risk associated with very harmful consequence need risk assessment & analysis.
· The above categorizations are qualitative in nature. For quantitative calculations one may need to take the help of probability and associated software which are also from various agencies for different applications (e.g. shell, DNV etc have proprietary software for their use).
4. Control measure: Control measure, preferred actions are to climb up the hill as shown in fig I/2.5.4-1 (based on Health and safety authority-www.hsa.ie/eng).
Fig I/2.5.4-1 Control measure for risk control
As shown in the drawing there are several steps listed below arranged in decreasing order of preference:
· Elimination of hazard: Total elimination is not always possible but some time possible e.g. if unleaded petrol is used attendants are not in the hazard of lead contamination
· Substitute: Sometimes to eliminate hazard particular material/ system for example is vulnerable can be substituted by other. On account of health hazard DEHA is substituted for hydrazine to scavenge oxygen from boiler water.
· Isolating: Isolating the hazard is achieved by restricting plant and equipment. For example in case of hazardous area process transmitters use flame proof enclosure or use IS circuit so that hazard does not reach electrical circuit or sufficient energy does not reach the hazardous area
· Engineering control: By redesigning the process and put barrier. Machinery guard is an example of the same.
· Administrative control: Adaptation of safe control practices and procedure through appropriate training etc.
· Personal protective equipment: Gloves, helmet etc. are used towards this.
5. Risk Target: this is a term often found in connection with Plant Hazard analysis. A risk target is measure that expresses the consequence of a risk in relevant terms of the project and organization concerned.
6. Risk Analysis: As per IE 60300-3-9 Risk analysis is “systematic use of available information to identify hazard and to estimate the risk to individuals, populations, property or the environment.” So essentially risk analysis find, organize and categorize sets of risks.
7. Risk Assessment: Risk assessment is one step further. This can be defined in terms of the following basic activities:
· Identification of hazard
· Analysis and evaluation of risk
· Find appropriate the way to control & mitigate hazard
The main aim of risk assessment is to remove hazard, or reduce the risk level by adapting necessary control measures, to move towards safety. Importance of risk assessment cannot be overestimated, because it provides a number of helpful things to prevent loss of assets (here asset stands for personnel, plant machinery, property , environment all). Major advantage shall include but not limited to:
· Make personnel at all levels knowledgeable about loss of asset due to hazard
· It makes them aware of all possible potential hazards their likelihood of occurrence, severity, level of risk etc.
· Identify risk level for each of personnel, asset, environment etc.
· Assess the existing control measures and gives new suggestions for change to protect asset
· When done at early design stage (may be with little extra investment), then future damages are saved to a great amount (e.g. good save for frequent loss of production, and /or loss of property due to say fire, explosion and /or environmental protection).
· Categorization of risk and help to take appropriate control measure.
8. Risk assessment procedure is an elaborate process but mainly covers the following major points. Detailed discussions on the same have been presented in clause 3 in chapter II.
· Hazard Identification
· Evaluation of risk; Likelihood, severity and level of risk
· Standard operating conditions
· Emergency situation (nonstandard operation)
· Review of all associated information
· Actual and potential exposure of personnel (latency, frequency, intensity)
· Environmental impact
· Design Engineering control
9. Risk management: As per ISO guide 73, risk management stands for “coordinated activities to direct and control an organization with regard to risk” defined above.