Accident Investigations and Case Histories University of Missouri

Accident Investigations and Case Histories University of Missouri Rolla Ch. E 258 Chemical Process Safety 6/7/2021 1

Overview Introduction Layered Investigations Investigation summary Case Histories Diagnosis (forensic engineering) Group Presentations Example 6/7/2021 2

Introduction Accident investigations and case studies provide opportunities to learn how to prevent similar accidents from occurring. Learn from someone else’s mistakes (don’t need to put your hand in a fire to know it will be burnt). Most companies willingly share this information to improve safety across the industry. 6/7/2021 3

Center for Chemical Process Safety (CCPS) UMR Connection – Dr. Randy Freeman, UMR alumnus and Academy member (1997), has held several leadership positions in CCPS – Dr. Joseph Louvar (author of textbook), UMR alumnus and Academy Member (2000), has served in the associated organization, SACHE which is the CCPS undergraduate Education Committee 6/7/2021 4

Accident Investigations. – Most modern accident investigations use the “layered” concept. – First layer Immediate technical recommendations – Second layer Recommendations to avoid hazard – Third layer Recommendation to improve management system – The layered approach helps to uncover the underlying causes 6/7/2021 5

Layered Accident Investigations WHAT is the purpose of the operation involved in the accident? WHAT equipment failed? WHAT material leaked (exploded, decomposed, etc)? WHICH people could have performed better? 6/7/2021 6

Questions for Layered Accident Investigations 1 WHAT is the purpose of the operation involved in the accident? WHY do we do this? WHAT could we do instead? HOW else could we do it? WHEN else could we do it? WHERE else could we do it? 1 from Trevor Kletz, Process Plants: A Handbook for Inherently Safer Design (Philadelphia: Taylor & Francis, 1998), p 175 6/7/2021 7

Questions for Layered Accident Investigations 1 WHAT equipment failed? HOW can we prevent failure or make it less likely? HOW can we detect failure or approaching failure? HOW can we control failure (i. e. , minimize consequences)? WHAT does this equipment do? WHAT other equipment could we use instead? WHAT could we do instead? 1 from Trevor Kletz, Process Plants: A Handbook for Inherently Safer Design (Philadelphia: Taylor & Francis, 1998), p 175 6/7/2021 8

Questions for Layered Accident Investigations 1 WHAT material leaked (exploded, decomposed, etc)? HOW can we prevent a leak (explosion, decomposition, etc. )? HOW can we detect a leak or approaching leak (etc. )? WHAT does this material do? WHAT material could we use instead? WHAT safer form could we use the original material in? WHAT could we do instead? 1 from Trevor Kletz, Process Plants: A Handbook for Inherently Safer Design (Philadelphia: Taylor & Francis, 1998), p 175 6/7/2021 9

Questions for Layered Accident Investigations 1 WHICH people could have performed better? Consider people who might supervise, train, inspect, check, or design better than they did. Also consider people who might construct, operate and maintain. WHAT could they have done better? HOW can we help them to perform better? (Consider training, instructions, inspections, audits, etc. , as well as changes to design) 1 from Trevor Kletz, Process Plants: A Handbook for Inherently Safer Design (Philadelphia: Taylor & Francis, 1998), p 175 6/7/2021 10

Example 12 -1 Pool Accident A drowning accident occurred during an open swim period. Approximately 100 children, ranging between 5 and 16 years old, were in and around a pool. An older child unknowingly pushed a 5 year old into the deep water. The pool is relatively crowded, and the 5 year old slipped under the water without being noticed by others, including the lifeguard. 6/7/2021 11

Example 12 -1 Pool Accident - Layered Investigation First layer: – Immediate technical recommendations 1) Paint pool depths at the pool edges. 2) Add more lifeguards. 3) Reduce the number of swimmers. 6/7/2021 12

Example 12 -1 Pool Accident - Layered Investigation Second layer: – Avoiding the hazard 1) Prohibit horseplay. 2) Zone pool to keep smaller children at shallow end of pool. 3) Add swimming lessons for all age groups. 4) Give all new swimmers (especially young children) a pool orientation. 6/7/2021 5) Add a roving lifeguard to monitor and control pool behavior. 13

Example 12 -1 Pool Accident - Layered Investigation Third Layer: – Improving the management system 1) Train lifeguards to alert supervision of observed potential problems. 2) Assign supervisor to make formal (documented) audits on a regular basis. 6/7/2021 14

Formal Accident Investigation Process Establish investigation team ASAP Brief survey of information available (on site if possible) Set objectives and delegate responsibilities Preincident facts gathered and organized Accident facts gathered and organized including detail examinations and photos Research and analyses to clarify perplexing evidence Report 6/7/2021 15

Formal Accident Investigation Report – Introduction – Process description (equipment and chemistry) – Incident description – Investigation results – Discussion – Conclusions – Layered recommendations 6/7/2021 16

Accident Investigation Summary – Complete formal accident investigation reports are detailed and not as useful for the average inquirer. Recently the “Investigation Summary”, a one to two page summary, has been used to spread information 6/7/2021 17

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Case Histories Case histories are written descriptions of accidents, including the causes, consequences, and methods required to prevent similar events. They are written by the personnel with the hands-on experience; the ones who know and appreciate the accident and accident prevention methods 6/7/2021 19

Case Histories “One learns from history or is doomed to repeat it” Especially true for safety; anyone working in the chemical industry can learn from case histories and avoid hazardous situations or ignore history and be involved in potentially life threatening accidents 6/7/2021 20

Forensic Engineering – The chapter contains several interesting tidbits to reconstruct what happened in an accident. • Burning rates for wood • Effects on metal at different T • Pressure rise with deflagration • Pressure rise with detonation • Bursting pressures – Eq. 12 -4, 12 -5 Cylindrical – Eq. 12 -6, 12 -7 Spherical 6/7/2021 21

Vessel Failure Can work in either direction 6/7/2021 22

Group Presentation – Two or three groups give presentation each day – Can use chalk board, models, Power. Point, overheads, etc. – If using Power. Point, must have it preloaded and ready to run. – Please hurry to class. We are on a tight schedule and need to start ASAP or earlier! 6/7/2021 23

Group Presentation – Plan on a 12 minute presentation with some questions at the end – Must be prepared to answer question (audience must be prepared to ask questions) – All group members must participate – Grading given as group – Rest of class will give a written evaluation of presentation – Participation as an evaluator is graded 6/7/2021 24

Group Presentations Since I need to be out of town on Monday, April 30, we will NOT have presentations that day. You can use the day to study for other classes or prepare you presentation. On Wednesday we will have only two presentations to allow us time to work the bugs out. After that, there will be three groups present each day. 6/7/2021 25

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