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Reducing PSM risk in Pharma- OPPI

Reducing PSM risk in Pharma- OPPI

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Reducing PSM risk in Pharma- OPPI

  1. 1. Reducing Process Risk in Pharmaceutical Industries Maharshi Mehta, CSP, CIH International Safety Systems, Inc. Baroda, India and Fairfield, CT, USA Maharshi.mehta@issehs.com www.issehs.com Seminar on – Emerging Trends in Environment, Health & Safety Management ORGANISATION OF PHARMACEUTICAL PRODUCERS OF INDIA April 2, 2004
  2. 2. Agenda  The Emerging Need for Process Safety  Hazard and Risk  Hazard and Hazard Identification  Process Controls that Reduces Risk
  3. 3. Driving Forces  Plant’s existence  Harm to people, process and environment  Process Interruptions  Regulatory and Corporate Requirements  Liability  Return on Investment  Recovery of resources  Savings from waste management  Pollution control at source  Share holder’s confidence  Pre-requisite to participate in Global Economy  Public Image  Press coverage  Court decisions  Major accidents
  4. 4. Public Image Survivors of NC pharmaceutical plant explosion work in Nebraska ……..” Jan. 29, 2003, blast that killed six people… "There were a lot of injuries ... a lot of bad burns, and so many people in shock," Howard said. "We tried to help, but most of us just prayed. It was a miracle of God that so many people actually walked out of there."
  5. 5. KINSTON, North Carolina (CNN) -- A massive explosion and fire Wednesday gutted a pharmaceutical supply plant, killing at least three people and injuring more than two dozen others -- about 12 of them critically. Authorities recommended residents within a mile radius around the plant to evacuate A volatile mix of air and suspended dust caused the explosion The explosion was so powerful it blew doors open on houses more The stock of West Pharmaceutical was halted on the New York Stock Exchange after the explosion, which is typical following a calamity North Carolina Governor
  6. 6.  The Occupational Safety and Health Administration said the plant was inspected in October, cited for numerous safety violations, including problems with the electrical systems design and use, inaccessible fire extinguishers and hazardous-waste operations, and fined about $10,000, which was reduced to about $9,000 early this month.
  7. 7.  North Carolina is the site of one of the nation's worst workplace disasters: Twenty-four employees and a delivery man died and 56 people were injured in a 1991 fire sparked when hydraulic fluid from a conveyor belt sprayed over a gas-fired chicken fryer at Roe's Imperial Food Products plant in Hamlet.
  8. 8.  April 1, 2002 RTE News  Two men were taken to hospital following an explosion and fire at a pharmaceutical company in Rathdrum, County Wicklow this afternoon. The two are believed to have suffered facial burns in the incident. An investigation is underway at the ABC plant.
  9. 9. Economic Impact  The stock of ABC was halted on the New York Stock Exchange after the explosion  resulted in an estimated $150 million in property damage  On June 30, 2003, two new European explosion protection regulations take effect. The first, ATEX 95, Directive 94/9/EC covers equipment and protective systems that may be used in areas endangered by potentially explosive atmospheres created by the presence of flammable gases, vapors, mists, or dusts. The second, known as ATEX 137, lays down the minimum requirements for improving worker health and safety in hazardous areas throughout Europe.  “Ergonomic-related illnesses remain the most frequent illnesses at ABC Pharma. In 2002, 43% of all illnesses and 65% of all lost time illnesses were musculoskeletal in nature and resulted in 1,450 lost days.” Excerept from MNC’s annual report  In 2002, many of our occupational illnesses and injuries resulted from chemical exposures. For example, the second most
  10. 10. Priority AReas  Driver Safety  Ergonomics  Hygiene  Process Safety  Safety Engineering  HIV/HBV exposure controls
  11. 11. Accident Occurred  Acetone bucket caught fire: 10 L metal container-plastic shoes- suspended bucket on valve  2” dia rubber hose used to fill metal drum with vinyl acetate- violent explosion (same operation conducted number of times without problems): External paints prevented grounding of the drum  N2 Purging was not enough: Fire in Centrifuge, Insufficient N2 flow- rota-meter 0-60 l/min, what needed was 150 l/min
  12. 12. Accidents Occurred-Contnd.  SAVASO, Italy-Dioxane released due to exothermic reaction. Critical Temp known was 230C. However it occurred at 180 C in absence of agitation  A runaway reaction occurred when gradual addition of material and observing temperature rise was done by operator in control room. Faulty temp recorder did not show rise in temp. Temp increase was indicated on a six-point recorder but it was not located at eyesight level.
  13. 13. Accidents Occurred (contnd)  Instruction-add methanol in waste product after applying vacuum and breaking it with N2. Instead, TO REDUCE AMOUNT OF WORK methanol was added directly resulting in to fire.  Not realizing that a vacuum/pressure of as little as 0.1 psi (vacuum of 2.5” wg, same hydrostatic pressure at the bottom of cup of tea) to 0.3 psi (Press of 8” wg) could collapse/burst a storage tank. 100 psi (7bar) of compressed air applied to clean choked line blew lid off.  Drain valve of dist. column. kept open for longer draining water and benzene
  14. 14. Accidents Occurred (contnd)  Sucking In occurred in tank because all three flame arrestors were choked.  After cleaning of a tank on hot day, vent was closed with plastic bag to prevent dust coming in. When rain cooled tank, it collapsed.  A tank being steamed, sudden rain cooled tank so quickly that vent could not draw-in air fast enough. 10 to 20” of opening was needed.  Content was pumped out more than air could get in quickly because of change in pump.
  15. 15. Why it Happened-Commonality  Because it has not happened in --years, it won’t happen  Concept of Inherently Safer Process Design was missing-  Sufficient redundancy not in place, redundancy design flaws or not working  Administrative Controls  Concept of system safety missing-e.g., PHA  Hazard Realization and Communication  Consequences of deviation not realized  Safe Operating Procedures not available or not blended with Operation Procedures  Preventive Maintenance often was Reactive Maintenance- Specifications on what to inspect not known/followed  Contractors-Weakest link of chain  ORGANIZATIONAL CONCERNS-e.g., Line vs staff function
  16. 16. Good News  “Working conditions in pharmaceutical plants are better than those in most other manufacturing plants” BLS  With the exception of work performed by material handlers and maintenance workers, most jobs require little physical effort. In 2002, the incidence of work- related injury and illness was 3.0 cases per 100 full- time workers, compared with 7.2 per 100 for all manufacturing industries and 5.3 per 100 for the entire private sector. 
  17. 17. Occupational Health and Safety Hazards (B2-3)  Chemical Hazards  Flammability  Reactivity  Toxicity  Dust Explosions  Compressed Gases and Cryogenic Liquids  Physical Hazards  Noise  Ionizing and non-ionizing radiation  Other Hazards  Cumulative Trauma Disorders (Ergonomics)  Mechanical Hazards
  18. 18. Flammability Fire Chemistry Ignition Source Oxygen Fuel Definition Flash Point Autoignition Temperature Lower Explosive Limits Upper Explosive Limits
  19. 19. Ignition Sources Electrical (23%), Smoking (18%) Friction (10%), Hot Surfaces (7%), Overheated Material (8%) Cutting, Welding, Open Flames (4%) Spontaneous ignition (4%)  Slow oxidation of low volatile compound with accompanying evolution of heat in non-ventilated area  Static Electricity (1%)
  20. 20. Ignition Sources-Static Electricity Non-Polar materials like hydrocarbons accumulate static charges readily as they have high insulating values  22 mJ of ignition energy from walking across a rug, many hydrocarbons require only 0.25 mJ  Flow of liquid through pipe, strainers, filters. In one test charge development with filter was 10 to 200 times high than without filter  Settling of conductive phase to non-conductive phase e.g., water in oil.  Splashing of liquid jets  Ejection of droplets from nozzles  Stirring and Mixing  Solid handling-Sieving, pouring, grinding, micronizing, pneumatic conveying
  21. 21. Fires and Explosions - Solvent Properties  Methanol: FP=12 deg C; LFL=6.0%; UFL=36%; Conductivity units=4.4x107 (high relative conductivity)  Toluene: FP=4 deg C; LFL=1.2%; UFL=7.1%; Conductivity units=<1 (very low relative conductivity)  Acetone: FP=-17 deg C; LFL=2.5%; UFL=13%; Conductivity units=6x106 (high relative conductivity)
  22. 22. Specific Conductivity of Selected Chemicals Liquid Specific Conductivity mho/cm Toluene <1x10-14 Xylene <1x10-15 Heptane Hexane <1x10-18 Methanol 4.4x10-7 Isopropanol 3.5x10-6 Water 5.5x10-6
  23. 23. NFPA and Indian Petroleum Act Classification of Flammable Chemicals NPFA Class I Flash Point < 100 F  Class IA Flash Point < 73 F (22.7C) and BP < 100 F  Class IB Flash Point < 73 F and BP > 100F  Class IC Flash Point > 73 F and BP > 100 F Class II Flash Point > 100 F (37.7 C) but < 140 F Class III A Flash Point > 140 F (60 C) <200 F Class III B Flash Point >200 F (93.3 C) Indian Petroleum Act  Class A: Flash Point < 23C, Class B: 23C-65C, Class C: 65 C- 93C
  24. 24. Flammability of Selected Solvents Chemical FP F(C) LEL % UEL % AITF(C) vap press mm hg Xylene 85 (32) 1 7 867(463) 10 Phthalic Anhydride 305(152) 1.7 10.5 1058(570) 0.00002 Styrene 88(31) 0.9 6.8 914 (490) 14.4 Methanol 52 (11) 6 36 867(464) 95 IPA 53(12) 2.2 13.7 750(399) 44 Toluene 40 (4) 1.2 7.1 896(480) 30 Acetone -4(-20) 2.5 13 869(465) 227
  25. 25. Flammability of Selected Solvents (Contnd) Chemical FP F (C) LEL % UEL % AIT F (C) VP mm /hg MEK 16 (-9) 1.4 11.4 759 (404) 78 Cyclohexane -4(-20) 1.3 8 473(245) 78 Methylmethacrylate 50(10) 1.7 8.2 435(815) 29 Butyl Alcohol 98(37) 1.4 11.2 650(343) 6 Butyl Cellosolve 143(61.6) 11 127 460(238) 0.8 Butyl Methacrylate 126(52) 0.9 4.9 562(294.4) 6 Butyl Acrylate 103(39.4) 1.5 9.9 4
  26. 26. Reactive Chemicals-Characteristics  High reaction rate  Reaction rate increases with temperature. Rate of reaction increases exponentially with increase in temperature. An increase of 10C roughly doubles the reaction rate in many cases.  If the reaction rate and resulting heat are not controlled , an explosion could occur.  Heat initiated decomposition could result in explosion e.g., certain peroxides  Light could be initiator of an explosive reaction e.g., hydrogen and chlorine reacts explosively in the presence of light.  Shock could initiate an explosion, e.g., acetylides, azides, organic nitrates, nitro compounds and peroxides.  Picric acid becomes highly shock-sensitive when its normal water content is allowed to evaporate.
  27. 27. Chemical Structure with Explosive Tendencies  -ONO2 nitrate R-NO2 aliphatic nitro  -NH-NO2 Primary nitramine Ar-NO2 aromatic nitro  -N-NO2 Secondary nitramine -N3  -NO nitroso =N-X halamines  -N=N-diazo -C=C-acetylides  -N=N-S-N=N-diazosulfide  Organic salts of chlorates, perchlorates, picrates, nitrates, iodates.
  28. 28. Dust Explosions-What is required for Dust Explosions  Presence of Combustible Dust  Min O2 Conc-3 to 15% v/v  Min Ign Energy (MIE) and Temperature (MIT)  Right Particle Size  <particle size, > the explosion pressure -<MIE and MIT  Rate of pressure rise of polythene dust explosion increase from 150 to 400bars/s when part.size reduced from 100 to 25 microns.  Minimum Explosible Concentrations (MEC)  MEC for most materials is 10 to 500 g/m3  10 g/m3 dust concentration looks like dense fog with visibility of 1Meter.  Moisture Content of dust: > Moisture, >MIE, MIT and MEC
  29. 29. Explosibility Index Type of Explosion Ignition Severity Explosion Severity Explosibility Index Weak <0.2 <0.5 <0.1 Moderate 0.2-1 0.5-1 0.1-1 Strong 1.0-5.0 1.0-2.0 1.0-10 Severe >5 >2 >10
  30. 30. Dust Explosion Characteristic of Selected Dusts Phthalic Anhydride Aluminum Powder Benzoic acid Explosibility Index >10 >10 >10 Ignitian Sensitivity 13.8 1.4 5.4 Explosion Severity 1.6 7.7 2.1 Max Expl Press, psig 72 84 76 Rate of Pressure rise psi/sec 4200 20000+ 5500 Ign Temp C 650 650 620 Ign Energey, J 0.015 0.05 0.02 Min Expl Conc oz/cuft 0.015 0.045 0.03 Limiting O2%, Inert Gas 14% CO2 2%CO2
  31. 31. Exposure Limits  Permissible Exposure Limit (PEL)  Threshold Limit Values (TLV)  Recommended Exposure Limit (REL)  Short Term Exposure Limit (STEL)  CEILING LIMIT  Conc. Immediately Dangerous to Life or Health (IDLH)  Lethal Dose, Concentration (LD50, LC50)
  32. 32. ODOR AS AN AID TO CHEMICAL SAFETY CHEMICAL TLV (ppm) AOT (ppm) Acetone 750 13 Ammonia 25 5.2 Arsine 0.05 0.5 Carbon monoxide 50 100.00 Chlorine 1 0.31 Chloroform 10 85 p-Dichlorobenzene 75 0.18 Ethyl alcohol 1000 84 Ethyl ether 400 8.9
  33. 33. ODOR AS AN AID TO CONTD.... Hydrogen sulfide 10 0.008 Methyl alcohol 200 100 Methylene chloride 100 250 Naphthalene 10 0.084 Ozone 0.1 0.045 Phenol 5 0.04 Toluene 100 2,9 Vinyl chloride 5 3000 m-Xylene 100 1.1
  34. 34. Exposure Limits for Selected Compounds Chemical TLV ppm STEL/C ppm AOT ppm IDLH ppm NFPA Rating H F R Styene 20 40 0.017-1.9 700 2 3 2 Toluene 50 skin 150 N 0.16-37 500 2 3 0 Xylene 100 150 1 900 2 3 0 Butyl Cellosolve 25 skin NA 0.1-0.48 700 2 2 0 1-Butanol 50 C Skin 1400 1 3 0 Methanol 200 250 6000 MMA 100 NA .049-0.34 1000 2 3 2 Phenol 5 Skin NA .012-.057 250 4 2 0 MM TLV- Threshold Limit Value AOT-Odour Threshold Value NFPA Rating-Hazard Rating H-Health, F-Flammability, R -Reactivity
  35. 35. Exposure Limits for Selected Compounds (Contnd) TLV mg/cum STEL/C mg/cum IDLH mg/cum NFPA Rating H FR Phthalic Anhydride 6.1 NA 60 3 1 1 Lead 0.05 NA 100 Chromium VI 0.05 0.1, 1 C 3 0 1 TiO2 10 Ref: 1998 ACGIH TLVs N-NIOSH Limits, C-Ceiling Limits
  36. 36. Physical Hazard-Noise  Health Effects:  Noise Induced Hearing Loss  Temporary and Permanent  Increased pulse Rate, Blood Pressure  Nervousness, Sleeplessness and fatigue  Health Effects Depends on:  Sound Level  Extent of Exposure  Frequency of Sound (audible 20 to 20K, Hz: Most Impact around 1000 Hz)
  37. 37. Noise -Allowable Levels Exposure Time (Hours) Max Allowable Sound Level (dBA) 8 90 6 92 4 95 3 97 2 100 1 105 1/2 110 Redusing Time by half will increase the allowable level by 5dB
  38. 38. Approximate Sound Levels Area/Activity Sound Level (dBA) Normal Conversation 65 Milling Machine 90-95 Tablet Press 80-90 Manual machining 80-85 Power Saw 100-110 Jet Plane 140-150 What will be Total Noise Level if two compressors-Each Produces Sound Level of 95 dBA?
  39. 39. Ergonomics-Cumulative Trauma Disorders-Back Injuries  Back Injuries  50 to 80% of working population affected  Account for 33 to 41 % of all compensation cost  Average Direct cost is about $10000/claim  Indirect Cost Could be eight times higher  Causes  Poor Equipment design Layout and Postures  Lifting-Turning around while lifting  Pushing/Pulling  Prolonged Sitting Standing
  40. 40. Why Hazard Identification “ For every dollar it costs to fix a problem in the early stage of design, it will cost $10 at flow sheet stage, $100 at the detail design stage, $1000 afte r the plant is build and $10,000 to cleanup the mess after an accident” KLETZ
  41. 41. Hazard Identification  Can the process/activity pose a threat to health, safety, environment or property?  INPUT: Properties of materials, historical experience, knowledge of process parameters, management system, available safeguards, application of analytical methods  Output: List of potential problem materials, process conditions, and situations and understanding of what can go wrong.  Conclusion: No known hazard exist, known hazards that can be controlled, sound controls may not control hazards
  42. 42. Hazard Identification (B1.32)  Accident and Incidence Investigation (B4)  Accident Analyses  Incidence Rate (#of lost time accidents x 20,000)/ Total Manhours  Frequency Rate ( #of lost time accidents x 106 )/ Total Manhours  Severity Rate (#of lost work days x 106)/ Total Man hours  Comparative analyses among employees, departments, companies, preceding months and years, for time, nature of accidents (e.g., burns, inhalation), cause of accidents and body parts affected by accidents.  Employee exposure monitoring. Workplace air monitoring.  Pre-startup survey and scheduled plant audits
  43. 43. PROCESS HAZARD ANALYSIS (B1.32)  Hazards of Process  Previous Incidents  Engineering and Administrative Controls  Consequence of Failure  Facility Sitting  Human Factors  Qualitative Factors
  44. 44. PROCESS SAFETY INFORMATION Hazards Technology Equipment Toxicity Block Flow Diagram Construction Materials PELs Chemistry Piping & Instrumention Physical Inventory Electrical Reactivity Operating Ranges Relief Vents Corrosivity Hazards of Deviations Design Codes Stability Material Balances Compatibility Safety Systems
  45. 45. Elements of Hazard Analysis  Implementation Plan  Process Safety Information (Hazards, Technology, and Equipment)  Prioritize the Process Hazard Analyses (PHA)  Conduct PHA According to Schedule in Standard  Schedule for Completing Actions Noted During the PHA  Operating Procedures (for each operating phase and for safety systems)  Certify Current Employees Sufficiently Trained  Document the Completion and Comprehension of Training  Contractor Injury Log
  46. 46. Elements of Process Hazard Analysis..Counted...  Procedures for Maintaining Mechanical Integrity  Document Process Equipment Inspections and Tests  Hotwork Permits  Management of Change Procedures  Incident Investigation  Emergency Action Plan  Process Safety Management Compliance Audits
  47. 47. Hazard Analysis - System Safety  Job Safety Analysis (JSA)  Preliminary Hazard Analysis (PHA)  What-if and What if -Check List  Hazard And Operability Analysis (HAZOP)  Failure Mode and Effect Analysis (FMEA)  Fault-Tree Analysis (FTA)  Management Oversight Risk Tree (MORT)  Human Reliability Analysis (HRA)
  48. 48. Time Estimate for Hazard Analyses Analyses Prep Time Evaluation Documentation Simple Comple x Simple Compl ex Simple Compl ex PHA 4-8 hr 1-3 d 1-3 d 4-7 d 1-2 d 4-7 d What-if Chklst 6-12 hr 1-3 d 6-12 hr 4-7 d 4-8 hr 1-3 wk HAZOP 8-12 hr 2-4 d 1-3 d 1-3 wk 2-6 d 2-6 wk FMEA 2-6 hr 1-3 d 1-3 d 1-3 wk 1-3 d 2-4 wk FTA* 1-3 d 4-6 d 2-4 d 1-4 wk 3-5 d 3-5 wk HRA* 4-8 hr 1-3 d 1-2 d 1-2 wk 3-5 d 1-3 wk * Model construction requires additional 3-6 d for simple process
  49. 49. Available Software for Hazard Analysis  PHA: HAZOPtimizer (A.D. Little, MA; PHA-PC, Primatech, OH)  What-if: SAFEPLAN (DuPont,CA)  HAZOP:CAHAZOP, NUS Corp, CA;HAZOP-PC, Primatech, OH;HAZOPtimizer, A.D. Little; HAZSEC, Technica, OH;HAZTEK, Westinghouse, PA;Leader, JBF Associates, TN;SAFEPLAN, DuPont.  FMEA: CARA, Technica; FEMA-PC, Primatech, OH; HAZOPtimizer, SAFEPLAN  HRA: HRA-PC, Primatech; SHERI, Bettelle, OH.
  50. 50. HAZOP EXAMPLE-Rasin Plant-Xylene Feed Ite m No Deviati on Causes Conseque nces Safe Guard Action 2.1 High Flow Rota Meter Fails Feed Valve Fails-Open ?? Calibrated quarterly Inspected quarterly Provide excess flow valve Low Flow No Flow Other Than- MT Contaminati n Reverse flow
  51. 51. CHAPTER 5 PREVENTION AND CONTROLS
  52. 52. Inherently Safer Process Design  A design incapable of causing injury no matter what you do  Emphasis on selection of safer chemicals, reducing inventory, vessels and machinery that can withstand extreme conditions and not rely on interlocks, alarms and procedures  Examples:  Using continuous process Vs batch process  Using fixed piping Vs hose connection  Replacing chlorine with ozone in water treatment  Use of dryshaft seals
  53. 53. Inherantly Safer Process Design  Open structure for storage processing of hazardous materials- Small quantity of flammable causes significant damage in closed building-In an accidental discharge of butadine in an enclosed process area of 133’x288’with flammable controls provided, an explosion caused 46 fatality, 8 by flying debris, 80% of concrete slab blown off  Use of pallets of flammable solids in place of finaly devided solids  Spring Loaded ballvale as drain valve in distillation column. Operator has to hold the valve open.  Installation of remotely operated emergency isolation valves
  54. 54. Hazard Prevention and Control-Principles (B2-3) Substitute Process Modification Engineering Controls Ventilation Administrative Controls  Site Safety and Health Plan/Site Controls  Housekeeping  Safe Operating Procedures  Confined Space/Hot Work Entry Permit System  Lockout/tagout Personal Protective Equipment
  55. 55. Substituted Chemicals From Product To Working Function Chlorinated solvents Aquious solution Tablet Coating Formaldehyde/Glutara ldehyde Phenol, Peroxide Disinfectant 10% benzene in isopropanol 10% toluene in isopropanol. Analysis of the intermediate para-nitrophenol. Carbon tetrachloride & chloroform Replaced by esters and ketones Many different analysis A TLC running fluid- chloroform 40, methanol 25, formic acid 7-has low threshold limit values. Changed to a TLC running fluid, toluene 40, acetone 5, 100% acetic acid 4. Chemical analyses.
  56. 56. Flammable/Combustible Liquids- Controls  Instrumentation used in Determining Explosive Limits  Keep in covered containers when not in use  Flammable concentrations to be kept below 10% of LEL when an ignition source is present  Grounding and bonding for static electricity protection  Use of non sparking tools/ intrinsically safe electrical apparatus and lighting  Flammable gas supply to include a non-return valve  Avoid using flexible hoses for transfer. If it has to be used use one with male female coupling  Seal-less pumps or mechanical seals
  57. 57. FLAMMABLE AND COMBUSTIBLE MATERIALS : STORAGE ROOMS  Allowable quantity per Table e.g., 5 gal/sq feet of floor area when fire protection is not provided and room fire resistance is 2 hrs  Intrinsically safe electrical wiring (Class I Div 2)  Liquid tight room  Ventilation to provide six air exchange rate per hour  Provide clear aisle of 3' wide  Stacking of containers one upon the other over 30 gal prohibited  Dispensing by approved pumps or self closing faucet
  58. 58. Tank Storage(B3.19)  Not to overfill-Consider expansion of liquid when heated, Gasoline expand about .06 F in volume for each 10 F increase in T  Measure metal thickness, weep holes, ultrasonic indicators.  Minimum Thickness (API 650) t=0.0001456*D*(H-1)*S  Maximum thickness 1/2”Smaller than 50’ dia nominal thickness 3/16”, >50<120 1/4”.  API Standard 2000 for venting of storage tanks  Wire Screen of 40 Mesh, parallel metal plates or tubes are also used and preferred  dikes provided with drain pipe with valve closed outside dikes Dikes > 6’ high not preferred,  loading rack to be located at least 25 feet away  Steel support to be protected by 2 hrs fire resistance covering  NFPA 11 for Foam system
  59. 59. Preferred Diking St. Tank Fire Pit Fire Wall Dike
  60. 60. Tank Storage  Leave about 1M depth of liquid when emptied to reuce fatigue of the base/wall weld.  Design vent for ---M3/hr of vapour and liquid to prevent overpresuring in overflow situation
  61. 61. Unloading of Tank Cars/Trucks of flammable liquids  Metallic gauging rod prohibited when ele power line is within 20’ of tank opening  DO not locate under power-line, if feasible. Special rules apply if loading/unloading has to be done under power-line  Setting of brakes, “STOP....”signs 25’ in front,  Bottom loading is preferred  Continuous present of the operator throughout unloading  No smoking, grounding/bonding connection  Truck loading rack be kept 25’ of tank, property (for Class I)  Grounding and bonding  Applying chocks on wheels
  62. 62. Static Electricity Controls  Bonding and grounding-Ground Resistance of < 1Mohms adequate  Min size No 8 or 10 AWG wire ohms  Metal to metal contact essential (painted surface)  Significance of relative humidity: 60-70% is required.  Testing conductivity of wire and connections  Avoid using clothes and shoes made of certain synthetic materials.
  63. 63. Static Electricity Controls  Avoid free fall of liq by bottom entry or extend fill pipe. Fill pipe to terminate within 6” from the bottom of tank  Flow of liquid less than 1 m/s, not to exceed 7 m/s  Antistatic additives. e.g., Addition of 0.3 to 1 mg/L of Stadis 450 (DuPont)  Plastics are available with antistatic additives such as carbon black  Grounding and Bonding During Charging of solids  Filters and other ristrictions, followed by long lenghth of satraght pipe line  Pipe diameter to be increased after significant accumulation of charge REF: Control of Undesirable Static Electricity - BS 5958, 1991
  64. 64. Designs to Prevent Fires and Explosions - Controlling Static Electricity  Bonding and grounding (see diagrams on page 224- 228 of yellow book)  Dip pipes (or deflector tubes)  anti-siphon holes  Relaxation time  consider letting vessels “rest” after transferring low conductivity solvents  Avoid open solids charging to vessels containing solvents (e.g., use of “flapper valves”)
  65. 65. Inerting/Purging  In general O2 concentration to be kept below <8% to prevent a dust explosion  Pressure Purging , Vacuum Purging, and Flow Through Purging  Pressure Purging-Fast, uses more N2  Vacuum Purging-Slow Used for small vessel  Flow thru- when vessel is not designed for pressure/vacuum  Condenced HC vapors in vertical N2 purging line from a tank to reducing N2 valve  Inspect that N2 supply infact is ocuuring weekly basis by testing O2 concentration in blanketed area.  Low pressure N2 alarm to warn about loss of N2 blanketing
  66. 66. Designs to Prevent Fires and Explosions - Inerting Example  Equation for sweep-through purging:  Qvt = V ln [(C1-C0)/(C2-C0)]  where Qv = volumetric flow rate of nitrogen (e.g., ft3/min or L/min.)  t = total sweep time (e.g., min.)  V = volume of vessel (e.g., ft3,, L, m3)  C0 = oxygen conc. of nitrogen (usually assume 0%)  C1 = initial oxygen conc. in vessel (usually 20.9%)  C2 = final desired oxygen conc. in vessel (typically 5%)
  67. 67. Designs to Prevent Fires and Explosions - Inerting Example Example: Given a 1000 U.S. gallon vessel (V = 133.7 ft3 or 3,786 L), a nitrogen purge flow rate (Qv) of 10 ft3 per minute (or 283 L/min.), a desired oxygen concentration (C2) of 5%, an initial oxygen concentration (C1) of 20.9%, and assuming that the oxygen concentration in the nitrogen (C0) is essentially 0% -- how many minutes of purging time are theoretically required? t = {V ln [(C1-C0)/(C2-C0)]} / Qv t = {133.7 * ln (20.9 / 5.0)} / 10 t = 19.1 minutes
  68. 68. Dust Explosion - Prevention and Controls  Inerting, Purging, to keep O2 Conc below MOC  Suppression  Explosion Venting  Process Isolation  Pressure Vessel Design  Control of Ignition Sources
  69. 69. Fire Protection (B3.15)  Minimum number of exits  The average recommended travel distance distance not to exceed 100’, in Storage area 200’  Exits not locked - Doors opening outwards-Free/unobstructed way to exit - Width of exit 30”-Width of an access to exit 36”  Illuminated Exit signs in place - Emergency lighting (NFPA 101)  Exits discharging outside building  “Not An Exit” sign for Doorways not used for exit i.e., closet  Fire Alarm system
  70. 70. Fixed Foam System for Storage Tanks(B3.12)  Foam Application Rate: For air foam system, at least 0.1 gpm/sq feet of liquid surface area of tank to be protected  Duration of discharge vary depending on Foam Discharge outlet (type 1 or 2) and flesh point of tank content. For xylene with FP<100F, duration of discharge is 30 to 55 minutes.  Minimum number of supplementary foam hose stream of 50 gpm required for up to 65’ dia tank is 1. Minimum operating time is 10 to 30 minutes.  One discharge outlet required for tank upto 80’ diameter.To be provided with effective and durable seal, frangible under low pressure.  Piping within dike buried or supported for mechanical damage.  Foam Control Valves at a minimum distance of 50’, outside dikes, for tank <50’ dia, one diameter for tank >50’diameter.
  71. 71. Peroxide forming agents  Dating on receipt, testing every 3 Mo to 1 year  Store in Opaque containers and exclusion of air preferably by N2 , except Class C agents provided with inhibitors that need limited access of air  Disposal upon peroxide formation, or within one month of opening or within 1 year after receipt whichever is earlier.
  72. 72. Peroxide Detection Tests  Add 1 to 3 mL of the liquid to be tested to an equal volume of acetic acid, add a few drops of 5% aq. potassium iodide soln., & shake. The appearance of a yellow to brown color indicates the presence of peroxides  Addition of 1 mL of a freshly prepared 10% soln. of potassium iodide to 10 mL of an organic liquid in a 25-mL glass cylinder should produce a yellow color if peroxides are present.  Add 0.5 mL of the liquid to be tested to a mixture of 1 mL of 10% aq. potassium iodide soln. & 0.5 mL of dilute hydrochloric acid to which Few drops of Starch soln. is added just prior to the test. If blue or dark-blue color appears within a minute shows the presence of peroxides.
  73. 73. Designs to Prevent Incidents - Pressure Relief Devices  Location of Relief Devices:  consider need for pressure relief on all vessels, including reactors, storage tanks, towers, etc.  blocked-in sections of liquid filled piping need thermal relief  PD pumps and compressors need relief on discharge side  storage vessels need pressure and vacuum reliefs  vessel jackets may need relief
  74. 74. References  NFPA 654-Standard for the prevention of Dust Explosions in Plastic Industry  NFPA 63- Standard for the prevention of Dust Explosions in Industrial Plants  NFPA-Fire Protection Handbook, 5th Edition  NFPA-101-Life Safety Codes  NFPA-69 Standard For Explosion Prevention Systems  The Human Factors Society, Santa Monica California, USA, American National Standard for Human Factors Engineering of Video Display Terminal Work Stations  HMSO, UK, Health and Safety at Work Dust Explosions In Factories, #22.  Bodurtha Frank, Industrial Explosion Prevention and ProtectionMcGraw Hill, New York  Royal Society for Prevention of Accident, UK, (ROSPA) Engineering Codes and Regulations for Lifting Appliances  ROSPA, UK Construction Regulation Handbook  AiCHE, Center for Chemical Process Safety, Hazard Evaluation Procedures, New York, USA
  75. 75. References (Contnd)  Wood, Fawcett, Safety and Accident Prevention in Chemical Operations, John Wiley and Sons, New York  Hammer W., Occupational Safety Management and Engineering, Prentice Hall, Englewood Cliffs, NJ, USA.  Construction Safety Council, Fall Protection Field Guide, Hillside, IL, USA.  ACGIH, Industrial ventilation, Cincinnati, OH, USA.  Fthenakis, Prevention and Control of Accidental Releases of Hazardous Gases, Van Nostrand Reinhold, New Yor, 10003

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