Scenario Based Auditing

Christo Zemering, General Electric PlasticsPaul Swuste, Safety Science Group, TUD

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)

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

Causes of major accidents (PSM)

Type of causes explanation

Physical causeshazards insufficient hazard recognition and evaluationmaintenance failing mechanical integritystart-up inadequate per-start-up safety reviewemergency inadequate planning and response on emergencieshot work inadequate maintenance during high temperatures

Organisational causesprocedures incorrect proceduresinformation inadequate or missing safety informationtraining inadequate or missing safety trainingaccidents repeating accidents following similar scenarioschanges inadequate management of change

Human factorsworkers insufficient workers participationhuman human factor

Causes of 34 major accidents and incidents

02468

10

121416

causes, physical causes, organisational causes, human

How do we manage Process Safety?OSHA 1910.119 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

PSM audit results

Plant 1 Plant 2 Plant 3 Plant 4 Plant 5 Plant 6

1. EMPLOYEE PARTICIPATION 67% 50% 67% 83% 83% 50%

2. PROCESS SAFETY INFORMATION 77% 77% 69% 83% 70% 64%

3. PROCESS HAZARD ANALYSIS 62% 54% 69% 74% 69% 48%

4. OPERATING PROCEDURES 80% 60% 56% 84% 20% 88%

5. TRAINING 90% 80% 90% 90% 55% 65%

6. CONTRACTORS 98% 90% 69% 98% 83% 87%

7. PRE-STARTUP SAFETY REVIEW 55% 47% 55% 70% 85% 85%

8. MECHANICAL INTEGRITY 87% 64% 85% 94% 63% 83%

9. HOT WORK PERMIT 70% 96% 62% 92% 56% 68%

10. MANAGEMENT OF CHANGE 60% 56% 60% 80% 56% 68%

11. INCIDENT INVESTIGATIONS 100% 100% 100% 100% 60% 65%

12. EMERGENCY PLANNING AND RESPONSE 96% 84% 80% 88% 76% 61%

13. COMPLIANCE AUDITS 86% 86% 86% 86% 86% 93%

Total PSM score 79% 73% 73% 86% 66% 71%

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)

What does this say about the riskfor a potential major event?

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

SBA, bow tie model

and

and

or

F1

F3F4

F5

F7

F8

F2F9

F6

and

and

or

F1

F3F4

F5

F7

F8

F2F9

F6

F10

F11

F12

F13

F10

F11

F12

F13

F10

F11

F12

F13

People

Equipment

Reputation

Environment

F11

F12

F13

Central event

Fault tree, scenario’s and primary barriers Event tree, scenario and effect reducing barriers

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

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

Dust explosion outside powder processing equipment

Mechanical sparks

Hot surfaces

Static electricity

OR

Powder spills

Insufficient cleaning

AND

Explosion outside

equipmentDust

Air

ignition

AND

Equipment not tightly

closed

Improper loading of

blender

OR

Uncontrolled hot work

OR

Area classification

failure

Insufficient cleaning

Dust fire/ explosion

Electr eqpIn area not dust tight

Equipment not tightly

closed

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