cn3135 lecture 1 - loss prevention

7/23/2019 CN3135 Lecture 1 - Loss Prevention

1/74

Process Safety, Health andEnvironment (CN3135)

Soh Guat [email protected]


2/74

Outline of CN3135 Importance of process safety design and

operation

Identifying safety and health hazards eg.HAZOP, Fault Tree

Predicting consequences

Design for sustainable processes eg. reliability

engineering, sustainable engineering

8/3/2015 CN3135 Introduction to Occupational Health and Safety 1 2


3/74

Module Learning Outcomes

On successful completion of this module, studentswill be able to:

Describe and identify chemical process hazards

Analyze and assess the potential impacts of

hazards on safety, health, and the environment(SHE)

Develop methods for controlling process hazardsand minimizing their associated risks.

Describe the principles and aims of sustainabledevelopment

Prepare for final year design project



4/74

Lectures and Tutorials Schedule



5/74

Lectures and Tutorials Schedule



6/74

Tutorial Exercises

Will be assigned by individuallecturers during each lecture



7/74

Module Assessment

Mid term test (date, topics, duration) 10%

HAZOP/ Reliability Engineering project 30%

Final Examination 60%



8/74

Textbook for CN3135


Chemical Process Safety:Fundamentals withApplications,International Edition, 3/e

Author : CROWL

LOUVAR

Publisher : PearsonISBN : 9780132782838


9/74

Expectations

IVLE/CN3135

Lecture materials - download

Tutorial problemsAttempt Register your project teams

oForm team of 4 5 members

oRegister: IVLE/Workspace/Groups/Sign-up

Bring textbook for lectures/tutorials



10/74

Lecture 1Introduction to Loss

Prevention


11/74

Learning Outcomes

Review major process safety accident cases

Assess loss prevention in process design andoperation

Analyse incident statistics



12/74

Why Process Safety ?

Unexpected releases of toxic, reactive, orflammable liquids and gases in processesinvolving highly hazardous chemicals


May result in huge loss oflives, property damage, impactthe environment and $$$


13/74

Source : The 100 Largest Losses, 1974-2013



14/74

Source : The 100 Largest Losses, 1974-2013



15/74

16

Major Process Safety Accidents

8/3/2015 CN3135 Introduction to Occupational Health and Safety 1


16/74

Video: Bhopal


http://www.youtube.com/watch?v=ELllSxnDS0g
http://localhost/var/www/apps/conversion/tmp/Videos/Bhopal,%20India%20-%2025%20years%20after%20Union%20Carbide%20gas%20leak.webmhttp://localhost/var/www/apps/conversion/tmp/Videos/Bhopal,%20India%20-%2025%20years%20after%20Union%20Carbide%20gas%20leak.webm


17/74

Taiwan Gas BlastKaohsiung


31stAugust 2014At least 25 fatalities and270 injured


18/74


Fire at Shell Bukom

Fire had started in the course of open de-oiling of

naphtha from a pipeline that ran through a pump

house at the refinery



19/74

Fire at Shell Bukom

Started 28th Sept 2011@ 1.15pm

Fire broke out in the pump room of Shell's half-a-million barrel per day Singapore plant

6 people suffered superficial wounds and 3 fire

engines were damaged from the fire Damage was contained to the vicinity of the

pump-house, in an area 50m by 150m

Caused temporary shut down of refinery

Extinguished 29th Sept 2011 @9.18pm

Final handover by SCDF 2nd Oct 2011



20/74

Shell was charged under Section 11(a) of the Workplace Safety and Health Act(Chapter 354A) for having failed in its duty as an occupier to take reasonablypracticable measures to ensure the safety of persons at its workplace



21/74

22

Source: www.wsh-institute.sg



22/74

23

Source: www.wsh-institute.sg



23/74

24

Source: WORKPLACE SAFETY AND HEALTH REPORT, 2014, WSH Institute

Workplace Injury Rate, 2006-2014



24/74

25

Occupational Disease Incidence Rate, 2006-2014

Source: WORKPLACE SAFETY AND HEALTH REPORT, 2014, WSH Institute



25/74

26

$10B costs

reported !

Source: Economic Cost of Work-related Injuries and Ill-health in Singapore, WSH Institute



26/74

Process Safety Focus

Prevention of incidents involving leaks, spills,fires or explosions

Facilities are well designed, safely operatedand properly maintained

Facilities are designed and engineeredproperly with systems to monitor and controlhazards

Includes technical, management andoperational systems working together toachieve desired outcome



27/74

Process Safety Pyramid

Source: WSH Guidelines on Process Safety Performance Indicators, WSH Council

8/3/2015 28CN3135 Introduction to Occupational Health and Safety 1


28/74

Definitions

Safety: Strategy of accident prevention. Mainemphasis is on worker safety

Loss Prevention: Prevention of accidents through useof appropriate technologies to identify and eliminatehazards before an accident occurs. Includes

protection of people, equipment, production, propertyand the environment

Hazard:An inherent physical or chemical characteristicof a material, system, process or plant that has the

potential for causing harm or damage Risk:A measure of the likelihood of occurrence and

consequence (severity) of an accident



29/74

Definitions


Spitting Cobra

HAZARD:Venom

Venom contactseyes may causeblindness

RISK:

Lower Risk Level


30/74

Definitions Accident: Incident which results in consequent

losses

Incident:An unplanned or undesired event thatadversely affects a companys work operations

Include work-related fatalities, major injuries, minorinjuries, first aid cases, occupational illnesses,property damage, spills, fires, dangerousoccurrences or near miss events



31/74

Accident Pyramid

Source: Chemical Process Safety, Crowl & Louvar

1

100

500

10 000

Disabling Injury

Minor Injury

Property Damage

No Damage



32/74

What is Acceptable

Risks?


33/74

Acceptable Risks

Any risk that is currently tolerated is consideredto be acceptable (US EPA)

Tolerable risk: risk which is accepted in a givencontext based on the current values of society(ISO & IEC)

Level of potential losses that a society orcommunity considers acceptable given existingsocial, economic, political, cultural, technicaland environmental conditions (UN)



34/74

Acceptable Risks

Cannot eliminate risks totallyAt design stage, need to decide if risks are

acceptable

< Normal day-to-day risks in non-industrialenvironment

Risks from multiple exposures are additive



35/74

Risk acceptance is a function of many factorsand varies considerably across industries

Company culture and the culture of the country

in which a facility is located influence riskacceptability

Risk acceptability is also time dependent -what is acceptable today may not beacceptable tomorrow, next year or next decade

Acceptable Risks



36/74


Workplace Safety and Health Act


37/74

38

Legal Requirements WSH (RiskManagement) Regulations



38/74

Risk Management using As Low asReasonably Practicable Principles (ALARP)



39/74

40

Latest Revision: 2015


Obtainable from WorkplaceSafety and Health Councilwebsitewww.wshc.sg


40/74

Safety and Health Hazards

Physical (eg. fire, explosion, noise, temperature, radiation) Mechanical (eg. moving parts of machinery, sharp edges,

work at height)

Electrical (eg. electricity, static electricity)

Chemical (eg. corrosives, toxic chemicals) Ergonomics (eg. back strain, repetitive strain injury)

Biological (eg. pathogens)

Psychosocial hazards (eg. human & cultural factors)



41/74

Sources of Hazards

42

huMan Machine Method

Material Physical

Environment

Organisation/ Work factors



42/74

Severity of HazardLevel Score Severity Description

5 5Catastrophic Fatality, fatal diseases or multiple major injuries

4 4

Major

Serious injuries or life-threatening occupational

disease (includes amputations, major fractures,

multiple injuries, occupational cancer, acute

poisoning, deafness, disabilities)

3 3

Moderate

Injury requiring medical treatment or ill-health leading

to disability (includes lacerations, burns, sprains,

minor fractures, dermatitis, work-related upper limb

disorders)

2 2

Minor

Injury or ill-health requiring first-aid only (includes

minor cuts and bruises, irritation, ill-health withtemporary discomfort)

1 1 Negligible Not likely to cause injury or ill-health

Code of Practice on Risk Management by Workplace Safety and Health Council



43/74

Likelihood of Occurrence

Code of Practice on Risk Management by Workplace Safety and Health Council


Level Likelihood Description1 Rare

Not expected to occur but still

possible.

2 Remote Not likely to occur under normal

circumstances.

3 Occasional Possible or known to occur.

4 Frequent Common occurrence.

5 Almost Certain Continual or repeating experience.


44/74

Risk Ranking and Risk MatrixLikelihood

Severity

Rare -

1

Remote

- 2

Occasional

- 3

Frequent

- 4

Almost

Certain - 5

Catastrophic -

55 10 15 20 25

Major - 4 4 8 12 16 20

Moderate - 3 3 6 9 12 15

Minor -2 2 4 6 8 10

Negligible - 1 1 2 3 4 5

Code of Practice on Risk Management by Workplace safety and Health Council



45/74

Acceptability of Risk Levels

Risk Level Risk Acceptable

Low Risk (1

3) Acceptable

Medium Risk (4 12) Tolerable

High Risk (15-25) Not acceptable

Code of Practice on Risk Management by Workplace safety and Health Council



46/74

Hierarchy of Hazard Control

So u r c e Pat h R ec ei v er



47/74

Chemical Plant AccidentAccident

Type

Scenario Outcomes Probability

ofOccurrence

Potential

forFatalities

ToxicRelease

Release +

DispersionToxic exposure

to employees

and

community

Low High

ExplosionIgnition in

confined space

Extensive plant

damageIntermediate Intermediate

Fire

Release + Ignition

l Pre-mix with air?

Low to

intermediate

plant damage

High Low toIntermediate



48/74

Nature of Accident Process

Most common consequence is fire

Highest percentage of large losses from vapour cloudexplosion

Toxic release can result in high human andenvironmental impact

Most frequent cause is mechanical failure (>50%),followed by operator error (18%) and design (10%) *

Most common hardware failure piping systems,reactors and storage tanks*

* Data from Chemical Process Safety by Crowl & Louvar



49/74

Sequence of Accidents

Initiation Event that starts the accident

Propagation Event(s) that maintain orexpand the accident

Termination Event(s) that stop the accidentor diminish it in size



50/74

Defeating the Accident Process

Step Desired Effect ProcedureInitiation Diminish Process design

Inert atmosphereIntrinsically safe equipmentGrounding, bondingProcedures, permit to work

Risk assessmentTraining

Propagation Diminish Construction materialsPlant layoutReduce inventories of materialsInstall check and emergency shutoff valvesEmergency material transfer

Termination Increase Install check and emergency shutoff valvesFire fighting, sprinklers, equipment &ProcedureRelief system

8/3/2015 51CN3135 Introduction to Occupational Health and Safety 1


51/74

Inherent Safety Principles

Minimise eg. inventory, size of tanks/reactors

Substitute eg. less toxic, less flammablematerials

Moderate eg. lower temperature, lower pressure,dilution, particle size

Simplify eg. Design for Safety, less maintenance,

housekeeping, easy to follow. Reduceopportunities for error



52/74

Bhopal Accident

Methyl isocyanate used in pesticidemanufacturing

Heavier than air

Reacts exothermically with water

Substitute with less hazardous chemical thatproduce a less toxic chloroformate

intermediate (Substitute) Decrease inventory of MIC on site (Minimise)



53/74

Video: Sugar Dust Explosion

Port Wentworth, Georgia


http://www.youtube.com/watch?v=Jg7mLSG-Yws
http://localhost/var/www/apps/conversion/tmp/Videos/%E2%96%B6%20Inferno%20Dust%20Explosion%20at%20Imperial%20Sugar.mp4http://localhost/var/www/apps/conversion/tmp/Videos/%E2%96%B6%20Inferno%20Dust%20Explosion%20at%20Imperial%20Sugar.mp4


54/74

Port Wentworth Accident

Conveying equipment not designed tominimise release of sugar dust and eliminateall ignition sources (Minimise)

Poor housekeeping (Minimise, Simplify) Company knows but fail to correct unsafe

condition (Company leadership issue)



55/74

Combustible Dust ExplosionAutomobile Metal Parts Polishing Supplier, Kunshan


2ndAugust 201468 fatalities, about 190 injured


56/74

57

TaipeiFormosaWater ParkFire



57/74


Fire at Shell Bukom

Fire had started in the course of open de-oiling of

naphtha from a pipeline that ran through a pump

house at the refinery



58/74

Shell Bukom Fire - 3 Main Lapses

1) Contractors drain naphtha from two openvalves and an open flange joint of the pipelineinto trays.

Naphtha vapour to escape into the atmosphere

resulting in an accumulation of flammablevapour, which would in turn pose a danger ofignition



59/74

2) Use of a plastic tray, which was a non-conductive container, as a receptacle forcollection of naphtha

Free fall of naphtha onto the plastic tray allowed

accumulation of static chargesA spark could be caused and be sufficient to

ignite the naphtha vapour which is withinflammable range in the atmosphere




60/74

3) Failed to deploy portable gas monitorssufficiently close to the open de-oiling area togive the warning when the build-up of theflammable vapour reached an undesirable level




61/74

Performance Monitoring

Provide assurance that process safety risks are adequatelycontrolled

Leading Indicators - monitor proactively the effectivenessof risk control systems and provide feedback on safetyperformance before an incident or accident happens

Evaluate present state of workplace through routine andsystematic inspections

Lagging Indicators when desired safety outcome hasfailed. Monitor reactively the effectiveness of risk controlsystems, identify gaps and weaknesses in these systems,

and report on incidents or accidents



62/74



Examples of Leading Indicators


63/74






64/74





65/74

Accident Statistics

Ministry of Manpower

Fatality Rate: per 100 000 employed persons



66/74

Accident Statistics

OSHA (Occupational Safety & HealthAdministration)

# of injuries & Illness*200,000

Total hrs worked by all employees

Incidence rate per 100 worker years

40 502000

hrs wk hrWorkYear

yrwk yr



67/74

Accident Statistics

FAR (Fatal Accident Rate): Fatalities per1000 employees over 50 years ( = 108 working hours)

Depends on no. of exposed hours

FAR = No. of Fatalities x 108

Total hrs worked by ALLemployees during period covered

[NB. 1 worker - 40 hr/wk, 50 wk/yr, and 50 exposed- yr/lifetime = 105 exposed-hr/lifetime]



68/74

Assessing Risks

Target FAR For planning, design to meet national or

company requirements

Sum of risks for most exposed person on site

< 2 deaths/108 exposed-hr

Single risk < 0.4 deaths/108 exposed-hr



69/74

Accident Statistics

FR (Fatality Rate): per person per year

Independent of hours actually worked

FR = No. of fatalities per year

Total no. of people inapplicable population



70/74

Assessing Risks

Acceptability Criteria

10-3/yr unacceptable10-4/yr public money spent to control

10-5/yr some degree of inconvenience10-6/yr no great concern



71/74

Engineering Ethics

Use knowledge and skill for enhancement ofhuman welfare

Be honest and impartial

Strive to increase competence and prestige ofengineering profession

Hold paramount the safety, health and welfareof public

(Extracted from American Institute of Chemical Engineers Code ofProfessional Ethics)



72/74

Your Role in Loss Prevention

Eliminate, design out the hazard

Mitigate the risk by reducing the severityand probability of occurrence of theincident



73/74

Zero Harm

V S ON

Z RO


Achievable?


74/74

Tutorial Questions 19th Aug

Attempt problems 1-1, 1-2, 1-4, 1-6(a), 1-22and 1-23 from textbook

3rd Edition

cn3135 lecture 1 - loss prevention

Documents