The Tutorial of Steps of Risk Assessment for Preventing Process Accidents - PowerPoint Presentation

1. The Tutorial of Steps of Risk Assessment for Preventing Process AccidentsSummary of the Process - Target OperationSTEP1 Grasp of Hazards regarding the Substances and the Process STEP2 Implement Risk Assessment① Identify trigger events and hazard scenarios② Estimation and evaluation of risk of the scenarios③ Consideration of additional risk reduction measuresSTEP3 Decision of the risk reduction measureYou can start from every step by Click1

2. 【Summary of the Process】1.Preparation①Inside confirmation②NitrogenreplacementManhole open/shutＮ２The process of having a mixing tank was chosen. After main raw material (powder) and auxiliary material (powder) are mixed, they are unloaded to the following process. This is a general mixing process.

3. 2.Operation Loading Mixing Unloading①Loading of main material by valve operation via the measurement tankＮ2Main material②Loading of auxiliary materialOpen Manhole andLoad to hopper by hand④Mixing: Operation of agitator (M100)⑤Unloading: Checking of acceptance tank.Unloading by valve operationEnd by timer.Checking by viewing③Nitrogen replacementMixture【Summary of the Process】

4. 3.Clearning①Gas scrubbing（N2→Air）Open manholeＮ2, ＡｉｒExhaustDrainageＡｉｒExhaust②Water washing using flexible hose③Drying by air【Summary of the Process】

5. 【Target Operation】Let‘s carry out risk assessment about 　　“2. Operation” – “①Loading of Main material”　 out of these processes.1.Preparation①Inside confirmation②Nitrogen replacement2.Operation (Loading, Mixing, Unloading)①Loading of Main material②Loading of Auxiliary material③Nitrogen replacement④Mixing⑤Unloading3.Clearning①Gas scrubbing②Water washing③Drying by air①Loading of Main material

6. Actually operations of this processDraining valveV110,V112,V113,V114 are shutCheck valves V100,V111,V115are always open.Air line V109 : ShutV105,V106 : ShutV105 : Shut (When PS105 is OFF)①Loading of Main material：Pressurized in the upstream.V100 : always openV102 : 50% openPressurized50% open

7. 【 STEP1: Grasp of Hazards Regarding the Substances and the Process 】The whole operation and the target operation were explained.Here, let's set up handling substances concretely. Here, main raw material is set at Polyethylene powder.Auxiliary material is set at polystyrene powder. Each mean diameter is 20 ～ 40 μm.　The target operations are summarized as follows.　“2.Operation – Loading”　“Draining valve V110,V112,V113,V114 : Shut”　“Air line V109 : Shut”　“N2 line V106 : Shut”　“①Loading of Main material：Pressurized in the upstream”Let's assemble the hazard scenarios which may occur when these are operated.

8. “No”　“No”　“Yes”“No”“Yes”“No”“No”“No”“No”Q1. Is investigation of hazard or toxicity (Risk Assessment, etc.) mandatory for the substance handled?Q2. Is the GHS classification of the substance other than “Not applicable,” “Not classified” or “TYPE G”?Q3. Is the substance combustible or flammable?Q4. Does the substance have an atomic group related to explosive or self-reactive property?Q5. Is the substance a combustible (e.g. organic, metal) powder (combustible dust)?Q6. Does the substance generate peroxides?Q7. Does the substance develop polymerization reaction?Q8. Is the substance liquefied gas?Q9. Is the substance suspected to be toxic despite the absence of SDS?Q3. Is the substance combustible or flammable?Some substances (gas, liquid, solid) without SDS that are not products can also cause fire/explosion (e.g. exhaust gas from petroleum refining, organic waste liquid, combustible waste. Please check with literatures, test data, etc. other than SDS.Two raw materials are plastics powder. Plastics powder burns with a easily. Since they actually burn when flame approaches, answer is “Yes”.Point : Since flammable gas or kerosene, etc. as fuel are common substances, there is not SDS. However, there is no doubt in these causing fire and explosion.Q5. Is the substance a combustible (e.g. organic, metal) powder (combustible dust)?Since both two raw materials are organic powder and combustible, answer is “Yes”. Point : Combustible dusts can cause explosion when they disperse in the atmosphere and are ignited. They may also fire spontaneously when piled up. This hazard is hardly shown in SDS.Q6. Does the substance generate peroxides?Since neither of two raw materials are found in the list of substances which generate peroxide (reference Table A5), answer is “No”.Point : Many peroxides are sensitive to shock and heat and can cause explosions. Because there is no GHS category for this hazard, it may not be possible to determine whether the substance is a hazard based on SDS.Q7. Does the substance develop polymerization reaction?Since neither of two raw materials are found in the list of substances which develop polymerization reaction (reference Table A6), answer is “No”.Point：Because there is no GHS category for the hazard of polymerization reaction, it may not be possible to determine whether the substance is a hazard based on SDS.Q1. Is investigation of hazard or toxicity (Risk Assessment) mandatory for the substance handled?The notifiable substances are listed in Table A1 of the reference. Please check whether the substance is in Table A1.Since no raw materials be found in Table A1, answer is “No”.Point : Many of the notifiable substances have not only toxicity but also explosive/flammable characteristics that are hazards leading to a process accident. If it is yes, implementation of risk assessment is decided. However, since the information is useful in steps 2 and 3, let's answer to subsequent questions.Q4. Does the substance have an atomic group related to explosive or self-reactive property?See Table A3 and Table A4 of the reference for examples of atomic groups. Please check whether the substance has specific atomic groups.Since neither of two raw materials have a specific atomic group, answer is “No”. Point : If the substance has an atomic group related to explosive or self-reactive property, it can rapidly decompose when energy (heat, shock, friction, etc.) is added and cause an explosion.Q8. Is the substance liquefied gas?Since neither of two raw materials are liquefied gases, answer is “No”.Point : Because liquefied gas is denser than gas in the gaseous form, destruction and eruptions lead to a large amount of gas. Because most liquefied gases are at a very low temperature, they are likely to fall under Q13 as well.Q9. Is the substance suspected to be toxic despite the absence of SDS?Since there are SDS about two raw materials, answer is "No".Point : Intermediates and residual materials can contain substances that are suspected to be toxic. Because most of them lack SDS, depending solely on SDS can lead to oversight of hazards.Q2. Is the GHS classification of the substance other than “Not applicable,” “Not classified” or “TYPE G”?GHS classification is listed in “2. Summary of hazards” of SDS. The hazard is not shown in the summaries of two raw materials.So, answer is “No”.Point : The probability of hazard is clear when some GHS classification is shown. A registry of the hazard is useful at step 2.At this stage, “Classification not possible” is deemed as having hazard. For detailed description of each classification, see Table A2 of the reference.STEP1 Answering the questions(1)First, Let’s Answer toSubstance Hazards

9. Next, Let's Answer to Hazards due to reaction/mixing of substance or physical conditions“No”“No” “No” “Yes” “No” Q10. Are reactions (including side/ competition reactions) generated intentionally in the process plant?Q11. Is there increase in temperature during some physical operation in the process plant?Q12. Are there possibilities of any of the followings due to intended or unintended mixing of substances in the plant?？(1)Increase in temperature(2)Generation of a substance that falls under the hazards of GHS classification in Table A2 of the reference (see Q.2)(3)Generation of large quantities of gas(4)Decreased thermal stability of the substance handledQ13. Does the process plant have parts that are not at ordinary temperatures and pressures (high/low temperature, high pressure, vacuum (low pressure), repeated temperature/pressure increase/decrease)?Q14. Does the process plant have a wholesale storage area?STEP1 Answering the questions(2)Q10 Are reactions (including side/ competition reactions) generated intentionally in the process plant?Since an intentional reaction does not occur, answer is “No”.Point：The intentional reaction in the process tends to progress under high temperature and pressure. When the temperature rises from the reaction condition, runaway reaction occurs. Temperature and pressure rise rapidly.Q13. Does the process plant have parts that are not at ordinary temperatures and pressures (high/low temperature, high pressure, vacuum [low pressure], repeated temperature/pressure increase/decrease)?Since main material is transported by compressed air, there is high pressure. Since that is repeated, there is repeated pressure. Answer is ”Yes”.Point : Parts that are not at ordinary temperatures and pressures experience high/low temperature, and repeated temperature increase/decrease. In terms of pressure, there are parts at high pressure vacuum (low pressure) and repeated pressure decrease/increase. Presence of such a part can lead to a leak of contents due to deterioration of sealed parts. Conversely, air or other substances can enter the process and react with the contents.Q14. Does the process plant have a wholesale storage area?Since the store of the substance is not wholesale. Answer is “No”.Point : Even when a hazard is not recorded in SDS, storage of large quantities of combustible substances (e.g. solid fuel from refuse, wood chips, shredder dust, rubble, tempura scraps, oily cloths) can lead to ignition and fire due to heat accumulation. Other than combustible substances, a large amount of stored ammonium nitrate has caused many huge explosions.Q12. Are there possibilities of any of the followings due to intended or unintended mixing of substances in the plant?(1)Increase in temperature(2)Generation of a substance that falls under the hazards of GHS classification in Table A2 of the reference material (see Question 2)(3)Generation of large quantities of gas(4)Decreased thermal stability of the substance handledBy SDS, since each powders is very stable substance, (1)-(4) does not occur. Answer is ”No”.Point : Mixing of some substances can cause (1)-(4). Any of them can cause unintended fire/explosions.Q11 Is there increase in temperature during some physical operation in the process plant?The process has mixing operation. But since that is slow, temperature hardly rises. Answer is “No”.Point ： Processes of physical operations other than intentional reaction include operations (e.g. absorption, mixing, dissolution, diluting) that can increase the temperature. Increase in temperature can cause unintended reactions including further heating, generation of toxic/combustible gas and explosions. This does not include intentional heating during operation. However, pay attention to the possibility that substances may react at a higher temperature.

10. Q15. Does the plant have parts prone to corrosion?Q16. Are there effect factors from the outside world (e.g. external corrosion due to rainwater, material degradation due to ultraviolet ray)?Q17. Does the process plant have high-voltage/ current places?Finally, let's answer to hazards due to other factors“No”“No””Yes”STEP1 Answering the questions(3)Q15. Does the plant have parts prone to corrosion?There is no part prone to corrosion. Answer is “No”.Point ： Metal equipment/devices corrode due to adoption of inappropriate steel types or use in an inappropriate environment and the like, which causes leak of the content. Air, water or other substances may enter through corroded pores and react with the content. Furthermore, lowering of strength of the corroded part may lead to rupture of the equipment/device if pressure is applied to them. Corrosion is caused not only by corrosive substances, but by various factors including contact of dissimilar metals, swift flow of the content and the effect of stress on the material.Q16. Are there effect factors from the outside world (e.g. external corrosion due to rainwater, material degradation due to ultraviolet ray)?Since the equipment is indoors, that is not influenced from ambient. Answer is “No”.Point ： External corrosion due to rainwater and material degradation caused by ultraviolet rays are effect factors easily overlooked when identifying latent hazards based on defects in operation, defects in equipment/devices, natural disasters and other external factors.Q17. Does the process plant have high-voltage/ current places?Since there is an agitator for mixing operation, there is high-voltage / current place. Answer is “Yes”.Point ： Electrification is an obvious hazard, but short circuit and earth defects themselves can cause ignition. Joule heat can cause explosion of electric wire materials.

11. ”Yes””Yes””Yes””Yes”3. Is the substance combustible or flammable?Flammable gas is more likely to cause fire/explosions.5. Is the substance a combustible (e.g. organic, metal) powder (combustible dust)? Combustible dusts may cause explosions when they disperse in the atmosphere and are ignited. They may also fire spontaneously when piled up.13. Does the process plant have parts that are not at ordinary temperatures and pressures (high/low temperature, high pressure, vacuum (low pressure), repeated temperature/pressure increase/decrease)? ？Contents may leak by deterioration of sealed parts. Conversely, if air or other substances enter the process, contents may react.17. Does the process plant have high-voltage/ current places?Short circuit and earth defects themselves may cause ignition. Joule heat may cause explosion of electric wire.Answer of STEP1Explanation of Table 4, Q.3Some substances (gas, liquid, solid) without SDS that are not products can also cause fire/explosion (e.g. exhaust gas from petroleum refining, organic waste liquid, combustible waste.) Among them flammable gas is very commonly used. For this reason, it is more likely to cause fire/explosions.Explanation of Table 4, Q.5Combustible dusts can cause explosions when they disperse in the atmosphere and are ignited. They may also fire spontaneously when piled up.Explanation of Table 4, Q.13Parts that are not at ordinary temperatures and pressures can lead to a leak of contents due to deterioration of sealed parts. Conversely, air or other substances can enter the process and react with the contents.All of the answer of other questions are “No”. Explanation of Table 4, Q.17Electrification is an obvious hazard, but short circuit and earth defects themselves can cause ignition. Joule heat can cause explosion of electric wire materials.

12. The record to the implementation sheetSTEP1 Grasp of hazards regarding the substances and the process Result of grasping hazards regarding the substances and the processItems for which “Yes” is circled3 Combustible/Flammable, 5 Combustible dust, 13 High pressure, Repeated pressure increase/ decrease 17 High-voltage/currentPoint : It is desirable to use accident data base and other sources also to investigate hazards of process accident occurrence at plant processes that are using similar substances or processes. It is desirable to investigate the hazards of substances and process in detail based on worker's experience.The process accident which may occur according to the hazards of the target substance and process is assumed by referring to description and cases of Table 4 and examples of possible effects of accident of Table 8.Implemented onYYMMDDImplemented (entered) by○○○○

13. STEP2Implement risk assessment①Identify trigger events and hazard scenarios（１）Confirm the purpose of works / operations or equipment / devices covered by Risk Assessment.Let's choose 2.Operation (Loading) : “Air line V109 : Shut” from operations.The purpose of this operation is “Dust explosion is prevented by the inert-gas replacement in the tank." The selected operation and its purpose are recorded to the implementation sheet.

14. STEP2 Implementation of risk assessmentOperation, equipment/devices and their purpose　The record to the implementation sheet（Operation）２．Operation（Loading / Mixing / Unloading）：Shut the V109 of Air line（Purpose） Dust explosion is prevented by the inert-gas replacement in the tank. Point : Trigger events must be found without a prejudice, although the operation which is likely to cause an accident tends to be chosen. Here, the events which causes failure or miss-operation are chosen. Let's check whether there is any event which causes the same failure or miss-operation as the past. The probability of fault is investigated with reference to Table 5-7.If the purposes differ even if it is the same work/operation/equipment/devices, risk assessment must be carried out about each.Table 5　Examples of discrepancies for investigation of defects related to works/operationsTable 6　Examples of defects related to equipment/devices　　（a）Damage to vessels/piping systems　　（b）Equipment failure　　（c）Loss of utilityTable 7　Examples of external factorsEach table is shown by Crick.

15. STEP2Implement risk assessment① Identify trigger events and scenarios（２） Identify the following 3 types as events that can actualize latent danger. Implement (i) to (iii) in any order.（i） Defects of the works/operations →　Table 5（ii） Defects of the equipment/devices →　Table 6 (a) (b) (c)（iii）External factors →　Table 7Here, let's consider (i) first. “The air line V109 is opened by mistake” is identified as the trigger event. Since the V109 shut by the preparatory was opened, this corresponds to "Unnecessary works / operations are executed (Table 5)". In Risk Assessment, it is important to exhaustively identify events that might actualize latent danger (trigger events) and scenarios leading to a process accident. Examine possible defects of all works/operations, equipment and devices. This does not mean that you need to identify all trigger events and consider and implement risk reduction measures all at one time.You may narrow down the scope of risk assessment in each case and implement measures in a few parts.

16. STEP2 Implementation of risk assessmentOperation, equipment/devices and their purpose（Operation）２．Operation（Loading / Mixing / Unloading）：Shut the V109 of Air line　（Purpose）A dust explosion is prevented by the inert-gas replacement in the tank. ①TriggerTrigger events (early events)(Reference: Tables 5 to 7)The record to the implementation sheetThe air line V109 is opened by mistake

17. STEP2Implement risk assessment①Identify trigger events and scenarios（３） Compile the process from trigger event to a process accident into scenarios.Since air always flows into T100 by open of V109, ③nitrogen replacement is insufficient.That is, the oxygen concentration in T100 may exceed limiting oxygen concentration (LOC).Then, during ⑤unloading, powder is dispersed by airflow in T100 and dust cloud is formed.If static electricity is charged by the agitate, static electricity may discharge. After that, dust explosion will occur.You will find that the substance “can cause fire/explosion”, because the answers to Q.3 “Combustible or flammable property” and Q.5 “Combustible powder” are “Yes”.Since the "combustible" of the three element of combustion is filled, if remaining two are filled, fire/explosion may occur. Let's consider hazard scenarios which fills the remaining "air" and "ignition source".By open of valve 109, the element of "air" is filled, and "dust cloud" is formed.Generally plastics are prone to be electrically charged. Collision of powder caused by agitation lead to static buildup, and can provide ignition source.Since combustible, air and ignition source exist together, process abnormality called powder combustion occur. And dust explosion occurs. Thus, the hazard scenario was identified.

18. Point of scenario identificationThe purpose of scenario identification is to promote awareness of trigger events that can cause process accident. Therefore, make an exhaustive examination as far as possible, considering everyday concerns and worries of workers as well as the person implementing Risk Assessment.When examining scenarios leading to a fire/explosion, keep in mind whether or not there are the three elements of combustion (fuel, oxygen and ignition source).When identifying scenarios, assume that the existing risk reduction measures are not implemented. This way, you can confirm how effective the measures are.It is advised to describe the situation from the trigger event to process accident in as much detail as possible so that you can understand the situation at a later review. Description is not necessarily limited to writing.

19. STEP2 Implementation of risk assessment① Identify trigger events and hazard scenariosTrigger events (early events)The air line V109 is opened by mistake(Reference: Tables 5 to 7)Process abnormalities (intermediate events)Process accidents(result events)The record to the implementation sheetSince air always flows into T100 by open of V109, ③nitrogen replacement is insufficient. The oxygen concentration in T100 may exceed limiting oxygen concentration (LOC). During ⑤unloading, powder is dispersed by airflow in T100 and dust cloud is formed. If static electricity is charged by the agitate, static electricity may discharge. After that, dust explosion will occur.Dust explosion may occur in T100.

20. STEP2Implement risk assessment②Estimation and evaluation of risk of the scenariosConfirm the presence or absence of existing risk reduction measures to prevent triggering events, process abnormalities (e.g. anomalous propagation of deviation in process parameters) and process accidents. If there are existing risk reduction measures, enter their content, type and the purpose.Mixing in inert atmosphere is the risk reduction measure about risk actualization of dust explosion. Because, if oxygen concentration is kept low, explosion will not occur (Three elements of combustion). Since reduction of the hazard frequency by nitrogen replacement is setting of operating condition, the type of measure is 【B) Technological measure】. Since explosion is prevented by oxygen removal among the abnormality propagation during the period from the initial event to a process accident, the purpose of this is 【c) Prevention of accidents】.※The operation purpose is clear in STEP2①(1). This may become a hint of judgement of the existence of the existing risk reduction measure.

21. STEP2 Implementation of risk assessment① Identify trigger events and hazard scenariosTrigger events (early events)The air line V109 is opened by mistake(Reference: Tables 5 to 7)Process abnormalities (intermediate events)Since air always flows into T100 by open of V109, ③nitrogen replacement is insufficient. The oxygen concentration in T100 may exceed limiting oxygen concentration (LOC). During ⑤unloading, powder is dispersed by airflow in T100 and dust cloud is formed. If static electricity is charged by the agitate, static electricity may discharge. After that, dust explosion will occur.Process accidents(result events)Dust explosion may occur in T100. ② Check existing risk reduction measuresA) Intrinsic safety measureB) Technological measureC) Managerial measureD) Use of personal protectionThe record to the implementation sheetMixing operation in inert atmosphere （B-c）

22. STEP2Implement risk assessment② Estimation and evaluation of risk of the scenarios (Part 1)Risk estimation and evaluation assuming there is no existing (functioning) risk reduction measures (part 1)Since air flows into T100 by open of V109, during unloading, powder is dispersed by airflow and dust cloud may be formed. Since the perfect exclusion of ignition source is impossible, there is probability of explosion. Therefore, it is estimated that hazard frequency is Moderate (△). Table 11（b）Dust explosion is expected as a result of the hazard. Dust explosion can inflict catastrophic damage to facilities in and out of the plant and production. Therefore, it is estimated that hazard severity is Fatal/serious (×). Table 11（a）As mentioned above, risk level is Ⅲ.　Table 11（c）

23. STEP2 Implementation of risk assessment② Check existing risk reduction measuresMixing operation in inert atmosphere （B-c）●Type of risk reduction measure A) Intrinsic safety measure B) Technological measure C) Managerial measure D) Use of personal protection●Purpose of risk reduction measures a) Prevention of abnormalities b) Detection of abnormalities c) Prevention of accidents d) Limitation of damage② Risk estimation and evaluation (Part 1)Assuming absence of existing risk reduction measuresSeverityFrequencyRisk level② Risk estimation and evaluation (Part 2)Confirm validity of the existing risk reduction measuresSeverityFrequencyRisk levelThe record to the implementation sheet×　　　　 △　 　　 　Ⅲ

24. STEP2Implement risk assessment② Estimation and evaluation of risk of the scenarios (Part 2)Risk estimation and evaluation assuming that the existing risk reduction measures confirmed in (1) are functioning (Part 2)Although nitrogen replacement is performed before mixing operation, there is no chance which can recognize the mistake in the operation. It is difficult to notice the airflow into T100. Therefore, it is thought that the frequency and severity of hazard do not change.As mentioned above, risk level does not change with III.In addition, when there is no existing risk reduction measure at (1), “Nothing" is recorded on the implementation sheet. The column of part 2 is recorded similarly to part 1.

25. STEP2 Implementation of risk assessment② Check existing risk reduction measuresMixing operation in inert atmosphere （B-c）●Type of risk reduction measure A) Intrinsic safety measure B) Technological measure C) Managerial measure D) Use of personal protection●Purpose of risk reduction measures a) Prevention of abnormalities b) Detection of abnormalities c) Prevention of accidents d) Limitation of damage② Risk estimation and evaluation (Part 1)Assuming absence of existing risk reduction measuresSeverityFrequencyRisk level×△Ⅲ② Risk estimation and evaluation (Part 2)Confirm validity of the existing risk reduction measuresSeverityFrequencyRisk levelThe record to the implementation sheet×　 　　　 △　　　 　 Ⅲ

26. STEP2Implement risk assessment③ Consideration of additional risk reduction measures(1) The risk level Ⅲ is not permitted. Consider risk reduction measures that should be added to lower the risk level.B) Technological measure - a） Prevention of abnormalitiesi) Open of V109 is detected by installation of the limit switch for V109. 【B) Technological measure, b)Detection of abnormalities】. The interlock system which obtains answer back from the status of the limit switch is installed. 【B)Technological measure, a)Prevention of abnormalities】. However, since it cannot operate exactly if the present operation is unknown, a sequence must be installed.B) Technological measure - b） Prevention of abnormalitiesii) The leakage from V109 is detected by installation of the flowmeter to the line of V109. 【B)Technological measure, b)Detection of abnormalities】. Moreover, the manual is revised as follows, valves must be exchanged if leakage is detected during v109 shut. 【C)Managerial measure, a)Prevention of abnormalities】.As shown in the gray column of the implementation sheet, there are four kinds of the types and the purposes of risk reduction measure, respectively. Let's consider various risk reduction measures, without caring about implementation difficulty, necessity cost, or risk level reduction, since they are taken into consideration later. The order of consideration is A)Intrinsic safety measure, B)Technological measure, C)Managerial measure, D)Use of personal protection.Since abnormalities here are V109 open, the open is detected. Then, it is good to close that automatically.How is the pair of the limit switch for detection of valve open and the interlock system by its signal ?The cause of abnormalities here may be not a mistake but valve defect, because it means that air flows although the valve is shut.The flowmeter installed in piping shows whether air flows or not. If a leakage is found, repair or replacement of the valve is needed. Let's correct the manual.A) Intrinsic safety measureIntrinsic safety measure is attained by eliminating factors indispensable to the scenario advance. In the case of measure to three elements of combustion, concrete they are "No combustible", "No air", and "No ignition source".Two raw materials must be changed into incombustible for "No combustible." That is, the processes must be reassembled from the origin. In practice, that is almost impossible.In a similar manner, realization of "No air" is almost impossible, as long as a worker needs to approach the equipment. Because the space suit for workers will be needed.Although "No ignition source" is not explained in detail, perfect removal is difficult like the above-mentioned two.As mentioned above, the intrinsic safety measure which can be installed was not found.

27. STEP2Implement risk assessment③ Consideration of additional risk reduction measures (continued)B) Technological measure - c） Prevention of accidentsiii) Let's use the oxygen concentration value measured by oxygen analyzer XI100 of already installed T100. 【B)Technological measure, b)Detection of abnormalities】. Operation of the agitator will not be permitted by interlock, if oxygen concentration is high at start-up of the agitator. 【B)Technological measure, c)Prevention of accidents】B) Technological measure - d） Limitation of damageiv) Damage of the chemistry equipment of T100 etc. is limited to when dust explosion occurs by installation of explosion venting. 【B)Technological measure, d)Limitation of damage】※ Since 【B)Technological measure】 and 【b)Detection of abnormalities】 are considered together in many cases, let's request cooperation to the technical expert of instrumentation.Since oxygen concentration is lowered for the dust-explosion prevention, let's pay attention to the oxygen concentration. Let's install the interlock which does not permit operation of the agitator when oxygen is high alarm. Then, dust cloud formation will be prevented.One of the limitation of damage about gas or dust explosion is explosion venting. Explosion venting is widely used in the drying device or the dust collector.

28. STEP2 Implementation of risk assessment③ Consideration of additional risk reduction measures & ③ risk estimation and evaluation (Part 3)Confirm the validity of the additional risk reduction measuresSFRThe record to the implementation sheeti） Open of V109 is detected by installation of the limit switch for V109.（B-b） The interlock system which obtains answer back from the status of the limit switch is installed.（B-a）ii） The leakage from V109 is detected by installation of the flowmeter to the line of V109.（B-b） The manual is revised as follows, valves must be exchanged if leakage is detected during v109 shut.（C-a）iii） Use the oxygen concentration value measured by oxygen analyzer XI100 of already installed T100.（B-b），Operation of the agitator will not be permitted by interlock, if oxygen concentration is high at start-up of the agitator.（B-c）iv） Damage of T100 etc. is limited when explosion occurs by installation of explosion venting.（B-d)

29. STEP2Implement risk assessment③ Consideration of additional risk reduction measures (continued)（2）Estimate and evaluate risk again by assuming the implementation of the additional risk reduction measures (Part 3)i）Since the probability of the V109 open by a mistake decreases with the installation of interlock, frequency of hazard decreases to “Rare (○)”. Severity of hazard does not change with “Fatal / serious (×)”. Risk level is Ⅱ.ii）Since V109 open is detected, and valves will be exchanged if leakage is found, frequency of hazard decreases to “Rare (○)”. Severity of hazard does not change with “Fatal / serious (×)”.Risk level is Ⅱ.iii） Since the operation probability when the oxygen concentration in T100 is high decreases with the installation of interlock, frequency of hazard decreases to “Rare (○)”. Severity of hazard does not change with “Fatal / serious (×)”. Risk level is Ⅱ.iv） Since the breakage probability of T100 decreases with the installation of explosion venting, the frequency of hazard decreases to “Rare (○)”. Severity of hazard does not change with “Fatal / serious (×)”. Risk level is Ⅱ.※ Note that measures other than 【A)Intrinsic safety measure】 only decrease frequency of hazard, and do not change severity of hazard.

30. STEP2 Implementation of risk assessment③ Consideration of additional risk reduction measures &③ risk estimation and evaluation (Part 3)Confirm the validity of the additional risk reduction measuresSFRi） Open of V109 is detected by installation of the limit switch for V109.（B-b） The interlock system which obtains answer back from the status of the limit switch is installed.（B-a）ii） The leakage from V109 is detected by installation of the flowmeter to the line of V109.（B-b） The manual is revised as follows, valves must be exchanged if leakage is detected during v109 shut.（C-a）iii） Use the oxygen concentration value measured by oxygen analyzer XI100 of already installed T100.（B-b），Operation of the agitator will not be permitted by interlock, if oxygen concentration is high at start-up of the agitator.（B-c）iv） Damage of T100 etc. is limited when explosion occurs by installation of explosion venting.（B-d)The record to the implementation sheet× ○ Ⅱ× ○ Ⅱ× ○ Ⅱ× ○ Ⅱ

31. STEP2Implement risk assessment③Consideration of additional risk reduction measures (continued)(3) Check whether or not the proposed additional risk reduction measures can be implemented.i)～iv) Risk level decreases by all of i)～iv), since they do not interfere with the existing risk reduction measure, those installation is possible.(4) Cautions to be communicated to workers in order to maintain functioning of the existing and additional risk reduction measures.i), iii) Check the sensor and actuator for interlock. Check operation of interlock periodically (several months).ii) Test the leakage of V109 periodically (several months).iv) Check visually daily. Check the existence of abnormalities periodically (several months).※ About check of operation or daily inspection, if each interval is clear, effectiveness will become good.(5) Record the results of risk assessment and other information to be communicated to workers after the start of production, if there are any.Check whether or not the proposed additional risk reduction measures can be implemented, considering the balance with the existing risk reduction measures and other restrictions.If there are residual risks (e.g. trigger events and scenarios at Risk Level II or lower,) make workers aware of possible occurrence of process accidents, while deciding on on-site responses.Not only the evaluation result of risk level but deal-with matter and notes are recorded as concretely as possible. That must be recorded so that workers can understand the purpose and type of the risk reduction measure.

32. STEP2 Implementation of risk assessment③ Can you implement additional risk reduction measures?③ Instructions to on-site workers in order to maintain the functions of the risk reduction measures③ Information to be communicated to on-site workers after the start of productionThe record to the implementation sheeti)～iv) Risk level decreases by all of i)～iv), since they do not interfere with the existing risk reduction measure, those installation is possible.i), iii) Check the sensor and actuator for interlock. Check operation of interlock periodically (several months).ii) Test the leakage of V109 periodically (several months).iv) Check visually daily. Check the existence of abnormalities periodically (several months).Is there a residual risk? [Yes] / NoHow do you handle the residual risk?Indicate the content and cause about the risk reduction measures, and the possibility of dust explosion in the manual about this work. Workers need to be educated periodically. Check rule and regulation about inspection, record, or management.

33. STEP2Implement risk assessment④Implement Risk Assessment by repeating the process from ① to ③Repeat the process of ① to ③.Identify a variety of trigger events in an exhaustive manner, and identify scenarios leading to a process accident. Consider necessary risk reduction measures for each scenario.It is necessary to identify trigger events and consider scenarios as exhaustively as possible. However, you don’t need to implement measures for everything at one time. It is important to implement Risk Assessment on a continuing basis by narrowing down the scope (running PDCA cycle) of risk assessment in each case to tackle the task in incremental steps.

34. STEP3Decision on the risk reduction measure① Compile the Risk Assessment implementation sheets (Table 2) completed for individual scenarios into one Risk Assessment implementation result sheet (Table 3) .Arrange the Risk Assessment implementation sheets completed in STEP 2 in descending order of Risk Level (III => II => I).② Decide on risk reduction measures based on a comprehensive judgment of technical, cost and other aspects starting from scenarios at high Risk Level.Overlooking a whole, risk reduction measures can be planned by compile of scenarios into one risk assessment implementation result sheet.If there is variability in the risk level judgment among scenarios, make corrections as needed.If the same risk reduction measures are proposed for multiple scenarios, you can implement them together.

35. Person name and DateNameYY/MM/DDResult of grasping hazards involved in the substances handled and the processOperation, equipment/devices and their purpose　　　　　　DatePerson name①Identify trigger events and scenarios②Check existing risk reduction measures②Risk estimation and evaluation(Part 1)Assuming absence of existing risk reduction measures② Risk estimation and evaluation(Part 2)Confirm validity of the existing risk reduction measures③Consideration of additional risk reduction measures & risk estimation and evaluation③Risk estimation and evaluation (Part 3)Confirm the validity of the additional risk reduction measures③Can you implement the additional risk reduction measures?③Instructions to workers in order to maintain the functions of the risk reduction measures③Information to be communicated to workers after the start of productionRemarksTrigger events（early）Process abnormalities（intermediate）Process accidents（result）SeverityFrequencyRisk LevelSeverityFrequencyRisk LevelSeverityFrequencyRisk Level　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　Result of STEP1Please copy the content of implementation sheet.STEP 2 Scenario 1 STEP 2 Scenario 2STEP 2 Scenario 3Decide on risk reduction measures based on a comprehensive judgment of technical, cost and other aspects starting from scenarios at High Risk Level.

36. ConclusionThe record for next time.This tutorial material finishes here.Thank you for taking a look to the last.For details, please refer to Safety Document or manual. (Sorry in Japanese)Risk assessment is not finished only at a time. If the arrangement store of the content of implementation is carried out, next effort will be reduced greatly.

37. Table 5 Examples of discrepancies for investigation of defects related to works/operationsOrder of operationsThe works/operations are not executedThe works/operations are executed in the reverse orderOnly a part of the works/operations are executedUnnecessary works/operations are executedDivergent works/operations are executedTiming of the operationsWorks/operations are executed too earlyWorks/operations are executed too lateTime period of the operationsWork/operation time is too longWork/operation time is too shortFilled quantityNo fillingExcessive filled quantityToo small filled quantityReturn

38. Table 6 Examples of defects related to equipment/devices(a) Damage to vessels/piping systemsVessels/ pipingDescriptionExamples of defects and process abnormalities that they causePipingThere are a large variety of piping in terms of flow rate, pressure resistance, corrosion resistance and other properties. Because vibration can accelerate deterioration, piping including joints requires inspection and management.Closing, increased pressure loss, reduction of internal pressure, insufficient pressure reduction, reverse flow, leak, leak-in, sudden change in pressure (water hammer)DuctMost of them have larger diameter and flow rate compared with piping. Often used as common equipment in air supply, exhaust and other systems.Defects similar to those of piping. Generally their pressure resistance and structural strength are inferior to those of piping. When they are used as common equipment without an inflow prevention measures, reverse flow can occur under an abnormal condition. If condensable process fluid flows exceeding the design conditions (temperature, pressure and air volume) the fluid may condense in the duct, which leads to leaks, deposition or (and) generation of combustible/heat storing modification (conversion) products.TanksGenerally used for gas or liquid but sometimes used for powder. Tanks are used for various purposes from temporary to long-term storage.Leaks, leak-in, rupture, change in physical properties (e.g. viscosity, temperature,) loss of volatile components, heat-retention, heating or cooling defect, uneven temperature distribution and discrepancy between the indication of level instrument and the actual fluid level can occur. Heat medium/coolant can leak from a tank with a jacket or internal coiling.VesselsWith smaller capacity compared with tanks. Many of them are normally pressurized or decompressed.Defects similar to those of tanks are possible. Pressurized or decompressed vessels require attention to their rupture, internal pressure reduction, insufficient pressure reduction, and rapid change in the pressure.ReturnVessels/ pipingDescriptionExamples of defects and process abnormalities that they causeContainersContainer closable with lid or stopper for transportation or storage. Because troubles due to insufficient maintenance are seen here and there, inspection and management are importantLeaks, leak-in, oxygen deficiency, deterioration of the content. Containers for transportation are themselves prone to deterioration Flexible hosePiping component indispensable for places with vibration, seismic countermeasures and expansion of handling range. Points are selection of materials with focus on permeability and endurance, inspection and management of loosening of jointsDefects similar to those of piping. Common problems include pressure resistance, material strength and aging degradationSight glassRefers to peep holes and liquid level gauge. Their weakness is in seal portions with metal parts, which requires maintenanceDefects similar to those of piping. Generally transparent parts (glass or plastic) are low in intensityGasket / sealnon-durable parts to maintain sealing property between parts. They are replaced by parts of the same specificationDefects similar to those of piping. They are likely to cause internal pressure reduction, insufficient pressure reduction, leak, leak-in and other defectscontinued

39. Table 6 Examples of defects related to equipment/devices(b) Equipment failureEquipmentDescriptionExamples of defects and process abnormalities that they causePressure relief /safety valvesValves to reduce pressure inside the equipmentInoperative, blocking, flow deficiency, leaks/leak-in in normal period. Counter flow of air tends to take place after atmospheric emission. Ignition can be caused by friction or static electricity at the time of emission. Foreign matters such as rust on the emitting part can cause trouble.PumpThere are suction pumps and feeding pumps. The point is to look at conditions of both the pump and the feeding/receiving part.Stop of flow, change in flow rate, mixing of air bubbles, changes in pressure, increase in suction pressure, mixing of components, leaks and leak-in can occur. In addition, the differential pressure with the receiving part causes unintended flow.CompressorCompresses and increases the pressure of gas. Heat is generated during compression.Same as pump but especially prone to decrease in flow rate and pressure. Use of flammable vapor sometimes leads to ignition. Agitator (mixer)Used to mix liquid with other liquid or dissolve solids in liquid. There are also mixers for separation prevention. Operation outside the design range leads directly to troubles.here may be separation of mixed substances, uneven temperature/concentration, and mixing of components. Weakness is at the agitator shaft and its sealing part, which can have fatigue breaking, leaks and mixing. ValvesThere are on-off valves and regulating valves, manual types and power operation types. Some can be remote controlled.Failure to open/close, failure to fully close leading to leaks, failure to fully open leading to flow deficiency. In addition to the above, regulating valves may have defects such as unchangeable opening and opening not as indicated. These defects may cause changes in liquid/pressure level and temperature change if the valve is for heat medium.Sensors and measuring equipmentMeasure pressure, temperature, flow rate, etc. Some are for control and others are for monitoring.When the measured value is out of the assumed range, measured value may be understated or overstated. There may be time-lag in measured values, or signals cannot be read. Measured values are unstable with variations. You need to think about loss of signals due to external factors and defects of display devices (understatement, overstatement, deviations, no display)Control systemsRequire power source for action. Measures such as multiplexing are possible. Operation may be continued without noticing abnormality.Any defects are possible in the controlled machines including behavior not as indicated and “inoperative.” An abnormal condition is likely to cause another abnormal condition. Sometimes it is dangerous to stop the system.VentsMaintain balance of internal and external pressure of a vessel, etc.Require attention to troubles similar to those of piping, ducts and pressure relief /safety valvesReturn

40. Table 6 Examples of defects related to equipment/devices(c) Loss of utilityUtilityDescriptionExamples of defects and process divergence that they causeElectricityWide range of use including control, power, lighting and heatingJust after a power outage, all electrical equipment including rotating equipment will stop or decrease functions. Use of back-up power source can avoid loss but hours of back-up are limited.NitrogenUsed for inert gas atmosphere and regulation of oxygen concentration. Liquid nitrogen is sometimes used to keep very low temperature.Immediate effect of supply stop is limited but the inert gas environment and the space with regulated oxygen concentration are disturbed. If liquid nitrogen is used to maintain very low temperature, the temperature is not maintained.WaterThere is cold water, water at room temperature and warm water based on the temperature. Water is sometimes used as power source.Divergence from the target temperature in the case where water is used for heating or cooling. In the case where water is used for dilution, there may be divergence from the designed concentration of the substance. When water is used as power source, supply stop may cause nonfunctioning or malfunctioning of the equipment.Cooling /heat mediaMedia for heat transfer. Used for heat pump.Divergence from the target temperature for cooling or heating at the supply destination.AirUsed for dilution, combustion, power, cooling, drying and other purposes.Shortage of air may cause unwanted variance in the concentration of the substance, or defects in combustion. There may be incomplete drying or cooling defects. When air is used as power source, loss will cause stoppage or malfunction of the equipment.VentilationUsed for moving out harmful substances, dust or the like, or replenishing consumed air.Increased concentration of harmful substances, mixing of impurities, increase in dust concentration, deterioration of work environment, defects in combustion or accidents due to lack of oxygen.SteamSteam is often used as heat medium/source but sometimes used for power.Similar to heat medium. Condensed water is prone to cause troubles (e.g. blocking, corrosion.)Return

41. Table 7 Examples of external factorsExamples of external factorsExamples of defects and process variances that they causePower outageDefects accompanying stoppage of all electrical equipment/facilities.Extreme weatherHeavy rain, floods, tidal waves, snow, low/high temperature damage, lightening strokes, thunder damage, gust, tornadoes, hail, typhoons, changes in barometric pressure, dew condensation, etc.Large-scale natural disaster (earthquakes, tsunamis, cracks in the ground, ground uplift/ subsidence, soil avalanches, landslides, avalanches, eruptions, etc.)Stock yards require fall prevention measures. The process includes off-site operations. Earthquakes and other natural disasters can trigger multiple factors simultaneously – destruction of equipment and loss of power/water, for example. In addition, disaster prevention/firefighting facilities may become unusable.Effect of an accident in the neighborhoodSpread of fire, incoming flying objects, blast wave, power outage, stoppage of common utilities, combustible gas, flammable liquid, inflow of toxic substances, etc.Vehicular collisionCollision between vehicles involves danger of vehicle fuel and chemical substances loaded on the vehicles. Collision between a vehicle and a facility involves danger intrinsic to the facility according to the level of the impact, in addition to the danger of vehicle fuel.Vandalism/sabotageDefects of any equipment/facility in an area vulnerable to intrusionReturn

42. Table 11 Criteria for risk estimation(a) Severity of hazardSeverity(degree of accident)Degree/indication of accidentFatal/serious (×)・Fatal accidents or those resulting in permanent damage to a body part・Accidents causing absence from work (one month or longer,) those resulting in a large number of victims at one time・Accidents inflicting catastrophic damage to facilities in and out of the plant and production (example: restoration takes more than a year)Moderate (△)・Accidents causing absence from work (less than one month,) those resulting in multiple victims at one time.・Accidents inflicting heavy damage to facilities in the plant and a part of production and requires a long period of time for restoration. (example: restoration takes about a six months)Slight (○)・Accidents without lost days, those involving slight wounds.・Accidents inflicting a small damage to facilities in the plant and a part of production (example: restoration takes about one month)Return

43. Table 11 Criteria for risk estimation(b) Occurrence frequency of hazard (likelihood)Occurrence frequencyDegree/indicationHigh or relatively high (×)・The hazard is likely to occur.(example: about once a year)Moderate (△)・The hazard can occur.(example: about once in the lifetime of the plant/facility (30 to 40 years)Rare (〇)・The hazard will be rare.(example: once in 100 years)Return

44. Table 11 Criteria for risk estimation(c) Risk levelSeverity of hazardFatal/serious（×）Moderate（△）Slight（○）frequencyHigh or relatively high (×)ⅢⅢⅡModerate (△)ⅢⅡⅠRare (〇)ⅡⅠⅠReturnRisk levelPriorityCautions concerning production startⅢThere is a risk that should be eliminated immediately or a serious risk.Don’t start production before taking necessary measures. It is necessary to invest sufficient management resources (money and labor)ⅡThere is a risk that requires prompt reduction measures.It is desirable not to start production before taking measures. It is necessary to invest management resources (money and labor) on a priority basis.ⅠThere is a risk that requires reduction measures as needed.Implement risk reduction measures as needed.(d) Description of the risk levels