HAZARDS ANALYSIS (HAZAN) DESIGN FOR SAFETY HAZARDS ANALYSIS (HAZAN)

HAZAN STUDY STARTS WITH THE SAME INFORMATION AND TEAM AS THE HAZOPS STUDY EXAMINES THE RESULT OF FAILURE OF EQUIPMENT OR CONTROLS INDIVIDUAL - SINGLE JEOPARDY MULTIPLE - DOUBLE JEOPARDY CAN BE ORGANIZED WITH FAULT TREE ANALYSIS (FTA) ALSO CALLED QUANTITATIVE RISK ASSESSMENT (QRA)

HOW MUCH SHOULD BE SPENT FOR SAFETY? tx.technion.ac.il/~dlewin/054402/LECTURE_13.pdf -

WHAT KIND OF RISKS ARE PRESENT? tx.technion.ac.il/~dlewin/054402/LECTURE_13.pdf

GENERIC FAULT TREE ANALYSIS FOR HAZAN WITH DOUBLE JEOPARDY EVENT OCCURS CONTROL SUCCEEDS CONTROL FAILS EVENT DOES NOT OCCUR GENERIC FAULT TREE ANALYSIS FOR HAZAN WITH DOUBLE JEOPARDY PRIMARY EVENT CONTROL RESPONSE SECONDARY EVENT

FAULT TREE SYMBOLS FAULT TREES USE PROGRAMMING SYMBOLS FOR EACH TYPE OF JUNCTION

EXAMPLE SHOWING FAULT TREE FOR LOSS OF COOLING WATER SUPPLY DUE TO FAILURE OF ELECTRICAL POWER SUPPLIES. http://www.s-2-s.org/modules.php?name=s2s_wp4&idpart=2&op=v&idp=1476 SEE NEXT PAGE FOR MORE DETAIL.

EXAMPLE SHOWING FAULT TREE FOR LOSS OF COOLING WATER SUPPLY DUE TO FAILURE OF ELECTRICAL POWER SUPPLIES. http://www.s-2-s.org/modules.php?name=s2s_wp4&idpart=2&op=v&idp=1476

http://www. s-2-s. org/modules. php http://www.s-2-s.org/modules.php?name=s2s_wp4&idpart=2&op=v&idp=1476

EXAMPLE SHOWING P&ID DIAGRAM FOR COOLING WATERSUPPLY http://www.s-2-s.org/modules.php?name=s2s_wp4&idpart=2&op=v&idp=1476

PROBABILITY ANALYSIS FROM HAZAN PROBABILITIES ARE MULTIPLIED FOR EACH LEVEL OF JEOPARDY FOR 2 EVENTS IN SERIES, EACH WITH A 0.5 PROBABILITY, PROBABILITY OF BOTH OCCURRING IS 0.25 SEVERITY MUST ALSO BE CONSIDERED AS A FACTOR IN CONSIDERING DOUBLE JEOPARDY SITUATIONS www.cobalt.chem.ucalgary.ca

PRIMARY SOURCES OF CATASTROPHIC EVENTS HUMAN ERROR MISLABELING TRIP FAILURES STATIC ELECTRICITY WRONG MATERIAL OF CONSTRUCTION FAULTY OPERATING PROCEDURES UNEXPECTED REVERSE FLOW COMPUTER CONTROL PROBLEMS IGNORANCE http://www.processforusability.co.uk/safety/images/larsen.jpg

INHERENT SAFETY OBJECTIVES ELIMINATE HAZARDS Eliminate the hazardous material Substitute a non-hazardous material Discontinue the operation http://www.acusafe.com/Hazard_Analysis/Hazard_Analysis-talks.htm#Talks%20and%20Papers

INHERENT SAFETY REDUCE CONSEQUENCES Reduce the quantity of the hazardous material Provide a curbed area with a drain to contain and evacuate a spill and produce a smaller pool area of a spill Separate the operation by adequate spacing to reduce exposure to adjacent operations and personnel http://www.acusafe.com/Hazard_Analysis/Hazard_Analysis-talks.htm#Talks%20and%20Papers http://altermondialisme.free.fr/monde/Etats_unis.jpg

INHERENT SAFETY REDUCE LIKELIHOOD OF INITIATION Reduce the potential for human error through simplicity of design Control ignition sources Provide redundant alarms http://www.acusafe.com/Hazard_Analysis/Hazard_Analysis-talks.htm#Talks%20and%20Papers

INHERENTLY SAFE DESIGN GUIDELINES TO REVIEW PROCESS DESIGN FOR SAFETY INTENSIFICATION SUBSTITUTION ATTENUATION LIMITATION OF EFFECTS SIMPLIFICATION KLETZ, TREVOR, PLANT DESIGN FOR SAFETY, HEMISPHERE PUBLISHING 1991

INTENSIFICATION POLICIES REDUCE QUANTITIES OF MATERIALS IN THE SYSTEM REACTORS TUBE FLOW VS. CSTR VAPOR PHASE VS. LIQUID PHASE DISTILLATION LIMIT INVENTORIES USE IN-COLUMN HEAT EXCHANGERS HEAT EXCHANGERS SHELL & TUBE VS. PLATE PROCESS FLOW IN TUBES http://www.inl.gov/featurestories/i/scwr.gif

INTENSIFICATION POLICIES STORAGE MINIMAL VOLUME STORAGE TANKS PIPELINES NUMBER OF TRAINS SINGLE TRAIN HAS SMALLER OVERALL INVENTORY THAN MULTIPLE TRAIN SINGLE TRAIN HAS FEWER LEAK POINTS SINGLE TRAIN HAS ECONOMY OF SCALE http://rphrm.curtin.edu.au/2006/issue1/defense05.png

SUBSTITUTION POLICIES USE LESS HAZARDOUS RAW MATERIALS USE LESS HAZARDOUS NON-REACTIVE COMPONENTS REPLACEMENT OF CFCs IN REFRIGERATION SYSTEMS AND AEROSOLS WITH HFCs AND N2 USE OF SUPERCRITICAL CO2 IN PLACE OF METHYLENE CHLORIDE FOR EXTRACTION USE OF WATER-BASED SOLVENTS FOR SEMI-CONDUCTOR PROCESSING USE STEAM AND WATER AS HEAT TRANSFER MEDIA INSTEAD OF HYDROCARBONS

ATTENUATION POLICIES USE LESS HAZARDOUS CONDITIONS FOR PROCESSES LOWER PRESSURES LOWER TEMPERATURES MULTIPLE STEPS NORMALLY COST EFFECTIVE SINCE PROCESS CONDITIONS ARE CLOSER TO AMBIENT

ATTENUATION POLICIES AMMONIA SYNTHESIS (KHARBANDA & STALLWORTHY, SAFETY IN THE CHEMICAL INDUSTRY, HEINMANN PROFESSIONAL PUBLISHING,1988) N2 + 3H2 → 2NH3 1930’S CASALE PROCESS AT 450 – 600 atm 1950’S ICI PROCESS 300 – 350 atm 1960’S KELLOGG PROCESS 150 atm 1982 ICI AMV PROCESS 80 - 100 atm http://www.topsoe.com/site.nsf/vIMAGESBYNAME/Ammonia28---PVC-diagram.gif/$file/Ammonia28---PVC-diagram.gif

LIMITATION OF EFFECTS KLETZ, TREVOR, PLANT DESIGN FOR SAFETY, HEMISPHERE PUB, 1991 CHANGE PROCESS SEQUENCE TO LIMIT HAZARDOUS CONDITIONS SEQUENCE OF PROCESSES NUMBER OF STEPS IN A SINGLE VESSEL USE OF SUBMERGED PUMPS TO REDUCE LEAK IMPACTS http://www.savinobarbera.com/images/istallazione-pompa-immersa-bg.gif

SIMPLIFICATION POLICIES STRONGER EQUIPMENT TO REPLACE RELIEF SYSTEMS MATERIALS OF CONSTRUCTION THAT RETAIN DUCTILITY (LOW TEMPERATURES) ELIMINATE EXCESS INSTRUMENTATION MINIMIZE NUMBER OF PIECES OF EQUIPMENT BY COMBINING SERVICES KLETZ, TREVOR, PLANT DESIGN FOR SAFETY, HEMISPHERE PUB, 1991

CLASS PROBLEM GIVEN: Automobile WANTED: Fault tree analyzing when auto fails to start BASIS: Engine powered car with remote starting switch SOLUTION: Present results as fault tree chart. Estimate probability for each component.