1. Scenario Based Auditing
Christo Zemering, General Electric Plastics
Paul Swuste, Safety Science Group, TUD
Specific way auditing. remains Toulouse disaster 5 y ago. Human tragedy, safety people like pictures
Final project work MoSHE DUT
Christo passed exam (1st), publishing, presenting

2. Outline Auditing High Risk Chemical Facilities
Causes of major accidents and incidents
How do we manage Process Safety ?
Is there a mismatch….?
Scenario Based Audit (SBA)
Outline, high risk chemical facilities. Comments on causes (material damage ± human victims)
2nd Process Safety management, how we organize, what regulator want.
Mismatch, room for SBA

3. Causes major accidents and incidents
Major (chemical) incidents are rarely caused by single failures, but the result of interaction between multiple failures; a chain of errors
Insufficient hazard recognition (design or operation) plays a role in many Incidents with reactive chemicals (CSB 2001)
Prevention is too much focused on top events only (Kletz 2001)
Major accidents are often preceded by a series of smaller accidents, near-misses, or accident precursors
quotes accident causation, familiar, keywords: multiple failures, ≠ hazard recog, prev events, accident precursors
Not efficient in preventing

4. Causes of major accidents (PSM)
Type of causes explanation
Physical causes
hazards insufficient hazard recognition and evaluation
maintenance failing mechanical integrity
start-up inadequate per-start-up safety review
emergency inadequate planning and response on emergencies
hot work inadequate maintenance during high temperatures
Organisational causes
procedures incorrect procedures
information inadequate or missing safety information
training inadequate or missing safety training
accidents repeating accidents following similar scenarios
changes inadequate management of change
Human factors
workers insufficient workers participation
human human factor
Co’s US. List, OSHA – PSM, EPA – RMP
PSM causes, physical, organisational and human causes.

5. Causes of 34 major accidents and incidents
Database , 34/100 events (chlorine gas emissions, extruder fires, dust explosions), completeness
Expert judgem 4 experts, 2 senior safety officers (HSE, PSM), 1 engineer 1 exp technician.
Acc. Indiv, group (PSM list) Org = dominant

6. How do we manage Process Safety. OSHA 1910
How do we manage Process Safety? OSHA Process Safety Management of Highly Hazardous Chemicals
1 Employee Participation
2. Process Safety Information
3. Process Hazard Analysis
4. Operating Procedures
5. Training
6. Contractors
7. Pre-Start-Up Safety Review
8. Mechanical Integrity
9. Hot Work
10. Management of Change
11. Incident Investigation
12. Emergency Planning & Response
13. Compliance Audit
14. Trade Secrets
How we manage PS, US
14 elements, independent saf experts audits regularly, ½ day/item, documentation, interview workers, assessing process conditions Score in %
Different from Eu, Seveso II, PSM no scenario analysis.

7. PSM audit results Plant 1 Plant 2 Plant 3 Plant 4 Plant 5 Plant 6
1. EMPLOYEE PARTICIPATION
67%
50%
83%
2. PROCESS SAFETY INFORMATION
77%
69%
70%
64%
3. PROCESS HAZARD ANALYSIS
62%
54%
74%
48%
4. OPERATING PROCEDURES
80%
60%
56%
84%
20%
88%
5. TRAINING
90%
55%
65%
6. CONTRACTORS
98%
87%
7. PRE-STARTUP SAFETY REVIEW
47%
85%
8. MECHANICAL INTEGRITY
94%
63%
9. HOT WORK PERMIT
96%
92%
68%
10. MANAGEMENT OF CHANGE
11. INCIDENT INVESTIGATIONS
100%
12. EMERGENCY PLANNING AND RESPONSE
76%
61%
13. COMPLIANCE AUDITS
86%
93%
Total PSM score
79%
73%
66%
71%
Results PSM audit, same protocol compare plants
green OK, red bad, plant 5

8. What do these audits tell ?
are processes in place that cover the intention of the described elements?
how robust are these processes implemented?
representative number of Field Checks confirm if the elements are implemented in practice
interviews with Employees give background to how well the organization is involved and how knowledgeable the people are
score of audit and the number of findings give a “good” or a “bad” feeling (++ rating)
Lot energy org. Audit = robustness processes (paper, shop floor)

9. What does this say about the risk for a potential major event?
essential question

10. Is there a mismatch.…?
Audits focus on implementation of SMS, and is performed per element, using standard questionnaires
no multiple failure scenario’s
no focus on detailed scenario’s
no focus on process disturbances
no identification of early precursors
audit findings are ‘single ticket’ items per element
no integral assessment
audit results are poor communication tool
mismatch PSM audit - current knowledge causes
no focus scenarios, process disturbances potentially disastrous events.
audit findings = ‘single ticket’ items, no integral approach.
Audits = % compliance, no info scenario management. Upper management no relevant questions.

11. SBA, bow tie model F1 F3 F11 F4 F2 F10 F9 F12 F6 F8 F13 F7 F5 and or
People
Equipment
Reputation
Environment
Central event
Fault tree, scenario’s and primary barriers
Event tree, scenario and effect reducing barriers
bow-tie, familiar model on conference. bow-tie = audit tool, prevent accidents
Knot = central event (CE), Lines = scenario’s, blocked by barriers
Hazard to CE (years), CE - losses (seconds)
Barriers: safety barriers (hardware) + man factors, blocking E stream, quality = man factors (SMS), which barrier, install, maintain, training

12. SBA, how does it work? Team selection
Select a major event, a ‘central event’
Construct the left side of the bow-tie
Define barriers
Audit barriers
format SBA simple. After CE selection bow rtie construction. Process disturbances.

13. SBA, resources per central event
Audit team
2 auditors
1 plant engineer
Plant team
PSM engineer
Process engineer
Operator
Maintenance technician
Day 1
Introduction
Create scenarios/bow-tie
Define barriers
Day 2
Define teams
Audit barriers
Day 3
Gather inputs, report out
Left = manpower, right = time (GEP experience)

14. Dust explosion outside powder processing equipment
Mechanical
sparks
Hot surfaces
Static
electricity OR
Powder
spills
Insufficient
cleaning
AND
Explosion
outside
equipment
Dust
Air
ignition
Equipment
not tightly
closed
Improper
loading of
blender
Uncontrolled
hot work
Area
classification
failure
Dust fire/
explosion
Electr eqp
In area not
dust tight
equip not dust tight, el eq not dust, ignition source.
inadequate housekeeping.
Conditions met, man factors insp, main monit inadequate.

15. Conclusions, advantages of SBA
improved hazard recognition
multiple failure scenarios
focus on barriers further away from a top event (the early precursors)
focus on management factors, link with SMS
effective communication tool to management
advantages SBA clear, hazard recogn, scen early precursors, part model.
man factors, quality barriers, more effective comm tool for man