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Appendix A RANKING GRAIN ELEVATOR HAZARDS 1 The panel, together with its liaison representatives and other specialists from the grain-handling industry, prepared over 150 hazard scenarios as the primary mechanism to identify grain elevator explosion hazards. A representative group of those scenarios is presented so that the method used by the panel for systematically ranking their recommendations can be descr ibed. The systems approach to hazard control, as shown in Figure A-1, requires two things--that all possible hazards be identified and that these identified hazards be ranked for significance. The panel realized that there are more than 150 explosion hazards in a grain elevator. However, by assuring that scenarios were written for every function or block in the FFBD (Figure 2), the panel was confident that they had a low probability of overlooking any major hazard and thereby had a realistic base for preventive action recommendations. Over half the scenarios included here represent actual accidents, and every recommendation by the panel is related to one or more of these scenarios. Therefore, the ranking method is based on a high degree of realism. Each scenario was reviewed for appropriate preventive actions (PA) by experts in the grain-handling industry, using the 35 different codes in _ . _ . . . . . . . . _ Figure A-Z as a stimulus to consider a wide range of posszbillttes. The applicable code for each preventive action is shown under the PA CODE Column for each scenario (for example, see Scenario No. 11 with its four proposed preventive actions). A cost was then estimated for each preventive action. Even though several preventive actions were proposed for each hazard scenario, the panel did not always elect to approve all such actions for implementation. Those actions shown with an ~X" in the APPROVED PA column were chosen for implementation, and the cumulative cost. of those actions are listed as CUMULATIVE PA COSTS. The panel then judged the hazard control potential for each scenario as described in Chapter 6 by averaging only those preventive actions approved for implementation. ~ Once these steps were completed, every scenario could then be judged against the three criteria in Figure A-3: severity (codes A through D), probability (codes J through M), and control resources {codes P through S). Once each scenario had its 3-letter code, it was placed in the Hazard Totem Pole of Figure A-4 to determine its significance among all other scenarios. The hazard significance code is the number opposite each 3-letter code in the Pole; e.g., the code for COP is 19. (For an explanation on the construction of the ordering of the 3-letter code in the Totem Pole, see Grose 1972.) 63

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1 64 To illustrate the process, Hazard Scenario No. 11 in this appendix has four proposed preventive actions. The panel selected only 2 of the 4 for implementation. The cumulative cost of these two was S7,000. me overall - potential for controlling that particular scenario when only implementing preventive actions 1 and 4 was judged to be ~medium.. Even though this scenario is ranked high on the Hazard Totem Pole (significance code 6), the panel did not consider it reasonable to implement preventive action 3 (which would have raised the control potential to ~high.) for an additional 3100,000 in an old country elevator. This should clearly show that hazard control potential-and hazard significance are totally independent of one another. When all the scenarios had been ranked in the Pole, the panel determined which preventive actions should be recommended, based on the most cost-effective use of resources to eliminate or control explosions. Starting with those scenarios at the top of the Pole, the specified preventive actions became the panel'~''highest recommendations. Proceeding downward in the Pole, there is a point where it is no longer prudent to continue inve~tment--either because control resources may have been expended or the remaining risk is acceptable. That point is shown in Figure A-4 as a cutoff. 1 The panel's recommendations for preventive actions were governed by this approach, and it can be used by those responsible for safety in elevators and mills in developing, evaluating, and implementing corrective actions. REFERENCES Grose, V. L. System" Safety in Rapid Transit, American Society of Safety Engineers Journal, 17~8) (19723:18-26 l

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65 1 \ _` 0 - o - :^ ._ _, o - 1 1~ V. lo' -:L In O. 1 _` .0 ._ C) 0 0 .P _, 0 0 0 52 o U) o lo: o A u] u] A H

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1 66 PA Code 1 2 3 4 6 7 8 9 10 11 ~2 13 14 15 ~6 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 3S FIGURE A-2 PERSONNEL Selection - Criteria PERSONNEL Selection - Methods , PERSONNEL Training - New Employee Tndoctrinstion PERSONNEL Training - In-Service Ccurses, Hazard Education PERSONNEL Qualification Validation - Formal Examination PERSONNEL Qualification Validation - Informal Periodic Review PERSONNEL Supervision - Job Assignment Versus Skill Level PERSONNEL Supervision - Assurance of Work Effectiveness PHYSICAL FACTLTTTES Design - Layqut/Arrangement/Modification PHYSICAL FACILITIES Design - Functional Capacity PHYSICAL FACILITIES Operations - Reliability/Operability of Functions PHYSICAL FACILITIES Operations - Sequencing/Scheduling of Functions PHYSICAL FACILITIES Maintenance - Techniques PHYSICAL FACILITIES Maintenance - Inspection ADMINISTRATION Policies - Non-Existent or Inadequate ADMINISTRATION Policies - Res trictive Scope AD~NTSTRATION Procedures - Operational ADMINISTRATION Procedu res - Jurisdictions 1 EQUT EMENT Function or EQUIPMENT Function or EQUTEMENT Operational EQUIPMENT Operational EQUI EMERr Ma intenance EQUIPMENT Maintenance ENVIRONMENTAL ASPECTS ENVIRONMENTAL ASPECTS ENVIRONMENTAL ASPECTS E~VIRON=NTAL ASPECTS Design - Utility or Physical Characteristics Design - Functional Capability Parameters - Functional Reliability Parameters - Human Operator Factors - Availability of Function (downtime factors) - Calibration Government Requirements - OSHA Government Requirements - DoA Government Requirements - EPA Social - Local Community ENVIRONMENTAL ASPECTS Social - Grain Industry Organizations ENVIRONMENTAL ASPECTS Legal - Tort Law ENVIRONMENTAL ASPECTS Legal - International Agreements ENVIRONMENTAL ASPECTS Political - Legislative Action TECHNOLOGICAL ASPECTS Research TECHNOLOGICAL ASPECTS Development ECONOMIC ASPECTS Grain Dust Hazard preventive action codes . 1

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67 Hazard Severity _ . . Buzzard Of feet on Ef feet on Of face on Code Severity Elevator Objec t lees Funct tonal Capab111 c y Personnel Safety _ . Catestrophic Tote1 loec of product with no Physical plane Is deacroyed Elevator enployeea, b~ctan~lere, alva~e All cuato~er or damped beyond effecelve or others are Icilled services terminated use b Critical - ,ority of product locc Too or Fore f~ctlone are Indoor ln~urlec occur to Only perclal alav~,e pocalble dleabled; elevator aunt be employees or b~rctenderc Customer services reduced to shut down low level ~ . __ _ . C Arsenal Only 75S of produce 1e eal- Teaporary dlaruptlon of Minor lnJurles occur to vagable Grain serulce. are elevator functlone; norm eaployeec or berate - era po~lble by l~prouleat lon operations can be restored in I day . D Ne~ll~lble No zl~lficant effect on No apparent die to No apparent hero to explode product or service to elevator operation or others customize rs Cod. I Deccriptlon of Slt~tlon 1 J The ldentifled hazard scenario could occur on the average of once ~ week ~ The Idea tl f led hazard scenario could occur on the average of once ~ Month . _ The ldent 1 f led hazard cenarlo could occur on the average of once year Be ldentifled hazard cenerlo could occur on the ver-.e of once decade Hazard Probabillty Hazard Ell~natlon Control Resources Cod' Calculated Dollar Equlvelence (Value of all resources required to either ellainate or control Che l"~tifled hazard ecenarlo; rewlelon of policy, procedures, manpower, dollars, technology, facilitl.e, ~terla le. and schedule ) _ _ P Preventive action for the ldentifled hazard will require less than $2,500 ., Q Preventive action for the identified hazard w111 require between $2,SOO and S50 000 ~ Preventive action [or the ldentifled hazard w111 require between S50.000 and S2SO OOO S Preventive ctlon for the ldentifled hazard w111 require Fore tom $250,000 FIGURE A-3 \ Hazard scenario ranking criteria 1 .

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1 68 ALP L21 \~3Q 3~P ~ ~ B3P 51 \~B 6r \~o " \ Au ,,] ~B9;P Ads 1 14' ~ ^MP B3~ B9;Q BLIP Cam l ALLOCATED RESOURCES 29 JO 31 32 34 35 36 37 L 38 39 42 ~3 44 45, 46 47 48 49 50 _ 51 B3S 25 26 27, 28' \OJ~ D3Q D%P \~B EBBS B~Q CaS Cam DY;Q DL,P GLB Dj5 DOPE 53/ ~ DLQ 54~ ~ - ~ P 55) - - - - ~ BM5 56' \CuS s7r~ -- - - - - - CAB ILcMs 63~ V\'5 DIES FIGURE A-4 Hazard totem pole. Cutoff (subjective)

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69 FUNiCTION: Elevate Grain Load / HAZARD SCENARIO DESCRIPTION: SCENARIO NO. FFBD NO. 10, 14, 20, 27 At a small country elevator a piece of tramp metal in a grain load is dumped into the pit and to a metal bucket leg. The metal becomes wedged in the boot area and the metal buckets rub against it. The buckets heat the tramp metal by friction and this ignites the dust in suspension in the leg. me explosion ruptures the leg casing but it is not sustained for lack of fuel in the surrounding environment. PROPOSED PREVENTIVE ACTIONS Tnstall magnet at point where all tramp metal would be picked up before entering the leg. Tnstall heavy screening in conjunction with the grate to halt the flow of tramp metal. Tnstall plastic buckets on the leg belt. PREVENTIVE ACT TON (PA) DISPOSITION: PA NO. PA CODE TOT AI COST OF PA APPROAtED PA 1 9 $ 2,000 X 2 9 -- 1~500 X 3 9 10,000 _ H. AZARD CUMULATIVE HAZARD HAZARD HAZARD HAZARD CONTROL PA SEVERITY PROBABILITY RESOURCE SIGNIFICANCE POTENTIAL COSTS CODE CODE CODE CODE High $3 ~ 500 B M Q 37 1

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1 70 l FUNCTION: HAZARD SCENARIO DE;CRIPTTON: l SCENARIO NO. 2 FEBD NO. 26 At a dirty interior subterminal elevator, the head pulley on belt conveyor works loose on shaft and moves over against the side of the casing creating a shaver of sparks that ignites a dust cloud over the conveyor discharge. This initial ignition propagates self throughout headhouse and gallery. Elevator virtually destroyed, several casualties and c ample te loss of grains. PROPOSED PREVENTIVE ACTIONS: - Establish a preventive maintenance program designed to police equipment for proper functioning. (new function) Establish periodic housekeeping inspection parameters. (new function) 3. Establish housekeeping system involving a mechanical dust collection system supplemented by manual means. PREVENTIVE ACTION (PA) DISPOSITION: PA NO. PA CODE TOTAL COST OF PA APPROVED PA 1 2 13 X 1 14 $ 15,000 (total cost X of PAnos. 1, 2, 3) 3 17 X HAZARD CUMULATIVE HAZARD HAZARD HAZARD HAZARD CONTROL PA SEVERITY PROBABILITY RESOURCE SIGNIFICANCE POTENTIAL COSTS CODE CODE CODE CODE High $15,000 A L Q 13 1

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71: l FUNCTION: Move Grain Load into Selected Storage HAZARD SCENARIO DE;CRTPTION: SCENARIO NO. 3 FEED NO. 11 This is a dirty export elevator. A new conveyor was added to service new storage bins. The frame of new conveyor not attached to existing system thereby not grounded. As tripper fills bin, a billow of dust reaches the ignition level which is ignited-by static electricity from ungrounded frame, arcing to grounded frame. The primary explosion propagates self throughout headhouse and gallery. Elevator destroyed, casualties result and inventory 106t. PRCIPOSE:D PREVENTIVE ACTIONE;: 1. Ground all conveying and electrical equipment. 2. Inspect system during construction. Install dus t collection system on trippers . Establish a housekeeping program involving a mechanical dust collection system supplemented by manual means. it: PA NO. PA CODE TOTAL COST OF PA APPROVED PA 19 S 500 X 2 14 600 X 3 10 35,000 X 4 13 165,000 X \ HAZARD CUMULATIVE HAZARD HAZARD HAZARD HAZARD (:ONTRCL PA SEVERITY PR08ABILITY RESOURCE SIGNIFICANCE POTENTIAL COSTS CODE CODE CODE CODE High S201,100 A L R 22 1 .

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1 72 l 1 FUNCTION: Move Grain Load into Elected Storage Bin HAZARD SCENARIO DESCRIPTION: SCENARIO NO. 4 FE'BD NO. 11 This is a clean export house. Dust accumulated under conveyor belt produces a friction fire. Burning dust ignites dust cloud. AS elevator is clean, damage is isolated. dust source traced to inadequate dust collection on tripper. PROPOSED PREVENTIVE ACTIONS: Establish a housekeeping program involving a mechanical dust collection system supplemented by manual means. Install reclaiming device at tail pulley. PREVENTIVE ACTION (PA) DISPOSTTTON: PA NO. PA CODE TOTAL COST OF PA APPROVED PA 1 13 $ 20,000 X 2 19 2,000 X HAZARD CUMUI.ATTVE HAZARD HAZARD HAZARD HAZARD CON]?RCIL PA SEVERITY PR013ABI LITY RESOURCE ~ ~ it, rem ~' 6.' HE POTENTIAL COSTS CODE CODE CODE OGRE _ High S22,000 C L Q 40 1

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1 l E1JNCTION: Elevate Grain Id . HAZARD SCENARIO DE=RI PTION: 73 SCENARIO NO. 5 FFBD N(:). 10, 14, 20, 27 In a large, clean interior sub-terminal elevator, a bucket on the leg rubs against leg casing causing friction and heating which ignites dust cloud, blowing out casing. No further damage. PROPOSED PREVENTIVE ACT IONS: Conduct rigorous preventive maintenance, especially on all parts of bucket elevators. 2. Install plastic buckets. 3. Use motion sensors to indicate belt slippage and misalignment. :PREVENTTVE ACTION (PA) DISPOSITION: - PA NO. PA CODE TOTAL COST OF PA APPROVED PA 1 13 $ 6,000 X 2 9 10,000 X 3 - 20 4,000 - l HAZARD CUMULATIVE HAZARD HAZARD HAZARD HAZARD CONTROL PA SEVERITY PROBABILITY RESOURCE SIGNIFICANCE POTENTIAL COSTS CODE CODE CODE CODE _ _ ~ _ High $16,000 C L Q 40 1

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1 104 FUNCTION: Uhload Grain Vehicle HAZARD SCENARIO DESCRIPTION: SCENARIO NOe 36 FFBD NO. 8 A concrete export elevator was unloading grain from a rail care Tail pulley bearing on the car receiving leg had failed to the point that when the oiler greased the leg, the lubricant passed through the hot bearing and flamed up inside the leg. The dust cloud in the operating leg exploded and spread to the belt conveyor.. Although the working space of the elevator was very clean, the newly covered conveyor contained cross bracings every 10 feet on which dust had accumulated to a depth of 6 inches. The dust fueled an explosion that destroyed the entire elevator, killing at least 10 people. 1 PROPOSED PREVENTIVE ACTIONS;: . Conduct rigorous preventive maintenance, especially on all parts of bucket elevators . - 2. Establish a housekeeping program involving a mechanical dust collection system supplemented by manual means (particularly for concealed areas). 3 . Us e heat sensors on cri tical bearings . PREVENTIVE ACTION (PA) DISPOSITION: PA NO. PA CODE TOTAL COST OF PA- APPRaVED PA 1 13 $ 8,000 X 2 13 180~000 X 3 - 20 5~000 X HAZARD CUMULATT~E HAZARI) HAZARD HAZARD HAZA~ CONTROL PA SEVERITY PROBABILITY RESOURCE SIGNIFICANCE NTENTIAL COSTS CODE CODE CODE CODE High S19 3,000 A L R 22 1

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10S FUNCTION: Maintenance 1 HAZARD SCENARIO DESCRIPTION: SCENAR]iO ND . 3 7 FFBD NO. N/A The office of a wooden country elevator wan being rebuilt following fire damage. An underground propane line had developed a leak and propane accumulated on the floor of the office after leaking from the line through sandy porous soil. me office basement was directly connected to the basement of the elevator. A painter entered the basement and lit a match to locate the light switch. The propane exploded and caused a secondary explosion throughout the elevator fueled by layers of dust on the walls and floors. The elevator was totally destroyed in the ensuing fire. Two were killed. PROPOSE D pREvERrIvE ACTIONS: - Examine the overall functions of mills and elevators to develop a totally new system less subject to the hazards of dust explosions. Establish a housekeeping program involving a mechanical dust collection system supplemented by manual means. PREVENTIVE ACTION (PA) DISPOSITION: PA NO. PA CODE TOTAL COST PA APPROVED PA 1 9 $ 2JOOO X 2 13 50J000 X HAZARD : CUMULATIVE HAZARD HAZARD HAZARD HAZARD CONTROL PA SEVERITY PROBABILITY RESOURCE SIGNIFICANCE POTENTIAL COSTS CODE - CODE CODE CODE High I $52,000 A M R 34 \ 1

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106 F uNcI~rIoN Elevate Grain Lot HAZARD SCENARIO DESCRIPTION: Corn was being unloaded from a concrete country elevator. Layered dust coated the walls, floors, and machinery; dust from a limited dust control system was returned continuously back into the leg. The casing was completely concrete to the top of the head pulley. The head pulley became displaced on the shaft and rubbed against the concrete housing. The friction between the pulley and concrete casing developed enough heat to ignite the dust cloud existing in the leg. The explosion broke out of the leg and caused secondary explosions throughout the structure. The elevator was virtually destroyed. Two fatalities resulted. SCENARIO NO. 38 FFBD NO. 10, 14, 20, 27 PROPOSED PREVENTIVE ACT IONS: , 1. Establish a housekeeping program involving a mechanical dust collection - system supplemented by manual means . Us e heat sensors on critical bearings . 3. If dust is returned to the grain stream, do it in the least hazardous manner. Follow, to the extent practical, the National Fire Protection Association's standard on explosion venting (No. 68) for all enclosures. Existing concrete structures should be vented by windows or other openings of the size dictated by this standard. PREVENTIVE ACTION (PA) DISPOSITION: PA NO. PA CODE TOTAL COST OF PA APPROVED P A 1 13 S 40,000 X 2 20 3,000 X 3 11 500 X 4 16 500 X HAZARD CUMULATIVE HAZARD HAZARD HAZARD HAZARD CONTROL PA SEVERI TY PROBABT LITY RESOURCE SI GNT FICANCE POTENTIAL COSTS CODE CODE CODE CODE High $44,000 A J Q 2

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107~ l SCENARIO NO. 39 . . FEND NO. 19 E1JNCTION: Store Grain bat HAZARD SCENARIO D~CRI"ION: . _ . Inadequate housekeeping had been practiced in an old wooden elevator used primarily for grain storage. A finned, space heater had been left on after the employees had left for home. During the night a fire broke out in a small, scale office in which the heater was located. Accumulated dust in the headhouse was placed into suspension and ignited by burning debris. Several subsequent explosions destroyed the elevator. PROPOSE D PREVENTIVE ACTION;: Establish a fire and explosion prevention training program . Quantify and enforce housekeeping standards for cleanliness to prevent fires and explosions. PREVENTIVE ACTION (PA) DISPOSITION: PA NO. PA CODE TOTAL COST OF PA APPROVED PA 1 - 4 $ 1,000 X 2 34 1,200 X HAZARD CUMULATIVE HAZARD HAZE HAZARD HAZARD CONTROL PA SEVERITY PROBABILITY RESOURCE SIGNIFICANCE POTENTIAL COSTS CODE CODE CODE CODE Me dium 32, 2 00 A J P \ 1 1

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1 108 1 FUNCTION: HA2ARD SCENARIO DESCRIPTION: SCENARIO NO e 4 0 FFBD NOe 8' 32 Corn was being unloaded from a truck send rail cars were being 1oadede The elevator was reasonably clean and had a good dust control system with the center of the headhause being pressurized. The leg became plugged and the f~r~mAn-attemoted to clear the plugged boot by jogging the drive motor. After a short period the leg belt parted at the head pulley and dropped dawn the leg. The dropping belt created a dust clald in the leg that was ignited by the burning belt. The leg casing broke open and air, because of the pressurization of the headhouse, rushed up the casing and into the handling system, carrying the burning dust with it. The leg and the handling equipment were damaged but no major structural damage occurred. nvo people were killed by the e ~1 as ion. PROPOSED PREVENTIVE ACTIONS: Conduct rigorous preventive maintenance, especially on all parts of bucket elevators . Use motion sensors to indicate belt slippage and misalignment. Apply state-of-the-art techniques to reduce the concentration of airborne dust in and emanating from elevator legs . PREVENTIVE ACTION (PA) DISPOSITION: PA NO. PA CODE TOTAL COST OF PA APPRoVED PA 1 1 13 $ 3~000 X 2 20 2,000 X 3 19 6~000 X HA2ARD CUMULATIVE HA2ARD HAZARD HAZARD HAZARD CONTROL PA SEVERITY PROBABILITY RESOURCE SIGNIFICANCE POTENTIAL COSTS CODE CODE CODE _ CODE High $11,000 A J Q 2

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109 l 1 SCENARIO NO. 41 FEED NO . 8, 3 2 FUNCTION: [ U ~ ~ Vehicle HAZARD SCENARIO DESCRIPTION: Corn from trucks and rail cars was being unloaded and a barge was being loaded at a steel tank and metal~clad river terminal elevator. Housekeeping was fair with dust collection on the legs only. Electricians, installing new wiring in the elevator, had opened some of the junction boxes in the truck receiving tunnel. An electrical arc from one box ignited a dust cloud in the tunnel resulting in a series of explosions. Rupture of the metal sheeting relieved the explosion pressure and structural damage was minimal. All the elevator legs exploded. The' most severely damaged was the barge loading leg to which collected dust was being returned. A number of employees were injured but there were no fatalities. PROPOSE D PREVENTIVE ACTIONS: . . Use a preestablished and enforced permit procedure whenever welding, cutting, wiring hookup, or open flame work is to be done. Apply state-of-the-art techniques to reduce the concentration of airborne dust below the lower explosive limit where possible in e nclosures other than legs . If dust is returned to the grain stream, do it in the least hazardous manne r . PA NO. PA CODE TOTAL COST OF PA AppRavED PA . . 1 17 $ 500 X 2 19 5,000 X 3 ~; 11 3,000 X HAZARD CUMULATIVE HAZARD HAZARD HAZARD HAZARD CONTROL PA SEVERITY PROBABILITY RESOURCE STGNIFTCANCE POTENTIAL COSTS CODE CODE CODE CODE ~ = = High $8, 500 B L Q 26

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1 110 1 EIJ~CTION: Convey Train to Designated Transportation Vehicle HAZARD SCENARIO DESCRIPTION: SCENARIO N() . 4 2 FE ED NO . 3 2 The operation of grinding milo in a small, country elevator had been slowed during the day because of a malfunctioning sifter. Two employees, working overtime, repaired the sifter and then loaded a truck with wheat from two of the elevator bins. ~ ~ I: _^ _ __- _ ~ _ About midnight the v nova a ~ cant an a smart enclosure -~ ~ called the ~ , _ _ _ , _ directly under the leg head. Deciding the light was a fire they fire department and then tried to extinguish the fire themselves. After applying the contents of three small fire extinguishers through a window in the enclosure, one of the employees left to get more extinguishers while the other remained at the site of the fire. Sensing that an explosion was about to occur, the employee at the site turned to leave and was blown off the roof to the ground, about 40 feet below. Grain dust in the structure had been ignited by a bare light bulb. The fire burned through the leg belt, which dropped, causing an explosion in the leg, damaging the head and boot areas. PROPOSED PREVENTIVE ACT IONS: l Use only equipment and installation standards meeting National Fn ectrica1 Code requ irements . Establish a fire and explosion prevention training program. Conduct rigorous preventive maintenance, especially on all parts of bucket elevators. PREVENTIVE ACTION (PA) DISPOSITION: PA NO. PA CODE 70E AL gosh OF P 1 APPROVED PA 1 16 $ 200 X 2 4 500 X 3 13 1,000 X HAZARD CUMULATIVE HAZARD HAZARD HAZARD HAZARD CONTROL PA SEVERITY PROBABILITY RESOURCE SIGNIFICANCE POT ENTIAI COSTS CODE CODE CODE CODE . High S1, 700 C J P 10 1

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111 E UNCTION: Convey Grain to Designated Transportation Vehicle HAZARD SCENARIO DESCRIPTION: ~- SCENARIO NO . 4 3 FEED NO. 32 An old, wooden elevator and mill had been converted to handling grain dust. Dust in one of the bins had gone out of condition, resulting in a fire. The fire department responded and apparently extinguished the fire. The elevator resumed loading out dust and when the bin was almost empty some burning dust from the previous fire entered and ignited the dust cloud in the bin. An explosion and fire resulted which completely destroyed the elevator. Three were seriously injured, but no deaths resulted. PROPOSED PREVENTIVE ACT IONS: Apply state-of-the-art techniques to reduce the concentration of airborne dust below the lower explosive limit where possible in e nclosures other than legs . 2. Establish a fire and explosion prevention training program. PREVENTIVE ACE ION (PA) DISPOSITION: PA NO. PA CODE TOTAL COST OF PA APPROVED PA . 1 19 $ 1,800 X 2 4 500 X HAZARD CUMULATI VE HAZARD HAZE HAZARD HAZARD CONTRa" PA SEVERITY PROBABI LITY RESOURCE SI (;NIFICANCE POTENTIAL COSTS CODE CODE CODE CODE Low $2, 3 00 A - L P 7 \ 1

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112 1 1 SCENARIO NO. 44 . . FEED NO. 10, 14 20, 27 E UNCTION: Elevate Grai n rem d . . HAZARD SCENARIO DESCRIPTION: An. employee in a dusty, small, country elevator smelled smoke and notified the manager. He ordered everyone to evacuate the elevator and called.the volunteer fire department, which arrived in about five minutes. Several employees accompanied the firemen.into the elevator to locate the fire. Smoke was souring out from the edges of 3' X 3' door in the floor leading into the. A leg pit. After opening the door slightly, an employee saw fire in the pit. fireman adjusted his haze nozzle to fog and told the employee to open the pit door. When the fog of water was played into the pit, it dislodged a massive amount of dust that exploded. Four men were injured, one seriously, and the elevator sustained major damage. The dust had.been ignited by a light bulb that was buried about 7' in a 14' depth of dust that had been allowed to collect in the pit. PRCeOSE D PREVENTIVE ACTIO=: Conduct rigorous preventive maintenance, especially on all parts of bucket elevators. . . . .. A; tablish a housekeeping program involving a mechanical dust collection system supplemented by manual means. Establish a fire and explosion prevention training program for employees and lore 1 f ire of f icials . A: PA NO. PA CODE T~ =~ OF P ~ APPROVED PA 1 13 $ 800 - X i\ 2 13 10,000 X 3 4 500 X HAZARD CUMULATIVE HAZARD HAZARD HAZARD HAZARD CONTROL PA SEVERITY PROBABILITY SOURCE SIGNIFICANCE POT ENTIAL COSTS CODE CODE CODE CODE 1 High S11,300 B . . K Q 16

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113 EVUNCTION: Elevate Grai n Load HAZARD SCENARIO DESCRIPTION: SCENARIO ~ . 4 5 FEED NO. 10, 14 20, 27 A small elevator of eight bins uses a screw auger to feed the leg boot. Some minor repairs are being done in the tunnel containing the auger. The leg is started and the repair man lays his tools on the tunnel floor. The bin chute on which he was working falls off at the bin exit and the grain falling from the bin sweeps his tools into the auger opening. A- pipe wrench is carried un the leg and jams the head pulley. The belt burns through and falls dawn the leg, the center portion of the leg being a concrete shaft containing 20 years of accumulated dust. She dust, ignited by the burning belt, explodes and destroys the midsection of the headhouse. The top house is damaged beyond repair. Two employees in the top house are brawn through the windows. One employee is killed, the other seriously injured. The elevator reopens 18 months later after $1 ,00 0 ,000 of repairs and reconstruction. _ _ . PROPOSE D PREVENTIVE ACTION;: . 1. Install gratings over the auger openings. 2. Install motion sensors on the leg belt and pulley. PREVENTIVE ACTION (PA) DISPOSITION: 1 PA NO. PA CODE TOTAL COST OF PA APPROVED PA 10 $ 500 X at, 2 20 1,000 X HAZARI) CUMULATIVE HAZARD HAZARD HAZARD HAZARD CONTRA PA SEVERITY PROBABILITY RESOURCE SIGNIFICANCE POTENTIAL COSTS CODE CODE CODE CODE Medium $1,S00 A R P 3 1

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