Introduction to Process Safety & Risk Assessment...Ahmad Shafaghi Safety: • Safe is not absolute • Safe is not necessarily zero • Safe is an acceptable level of risk Risk •

Introduction to Process Safety & Risk Assessment

University of West Indies

Ahmad Shafaghi

October 4, 2013

Basic Concepts & Process Hazard

Ahmad Shafaghi

� Overview of Trinidad & Tobago Process Industry

� Basic Concepts & Process Hazard

� Texas City Disaster (Video)

� Layers of Protection

� Hazard Impacts

� Risk Assessment

Seminar Contents

Ahmad Shafaghi

� This segment of the presentation tends to help answer

these questions:

• What are safety, hazard, risk, harm, etc.?

• What’s the relationship among these concepts?

• What are personal Safety and Process Hazards?

• What are the targets of Process Hazards?

• What is Process Hazard Analysis?

• What are the Process Hazard Analysis Outcomes?

Basic Concepts & Process Safety

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Confusing Terms?

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� Safety:

• Safe is not absolute

• Safe is not necessarily zero

• Safe is an acceptable level of risk

� Risk

• Risk is the probability of harm

• Any action inherently is risky

− Driving to work/university; walking around Savannah; crossing a road; staying home; arguing with spouse/girlfriend; working in a chemical plant; flying airplanes, etc.

• No matter what action you take, there is always a risk

• Zero risk applies to dead people only.

Safety and Risk Relationship

Ahmad Shafaghi

� Hazard:

• Hazard is a physical entity/condition

• Hazard is innate in all physical entities

− A swimming pool; a propane tank; a cigarette; a gun; an automobile, a pump, etc.

• Hazard is not risk

� Risk

• Risk is the outcome of a hazardous event

− Swimming in a pool; using of a propane tank for heating; smoking a cigarette; playing with a gun; driving an automobile; operating a pump, etc.

• Risk has targets; which could be human beings, the

environment or the facility

Hazard and Risk Relationship

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Facility Hazard Types

Process Hazards

EnvironmentalHazards

personalHazards

Health, Safety & Environmental (HSE)

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� Injuries and illness

(e.g., falls, slips) during

day-to-day operations

� Uncontrolled personal

exposures to sources

of energy:

• Electrical current

• High pressure

• Cryogenic materials

• Heat sources

personal Hazards - I

Ahmad Shafaghi

� Accidental personal

exposure to corrosive

materials

� Chronic personal

exposure to toxins or

radioactive materials

� Chronic personal

exposure to high decibel

noise levels

� Unprotected personal

exposure to dust and

insufficient breathing air

personal Hazards - II

Ahmad Shafaghi

� Air emissions (Pollutants and Greenhouse Gasses)

• Carbon monoxide (CO); carbon dioxide (CO2); nitrogen oxides, NOx (NO, NO2); sulfur oxides SOx (SO2, SO3), etc.

• Fugitive emissions: hydrogen, methane; volatile organic gases (VOGs) and inorganic acid, e.g., hydrogen fluoride, etc.

• Particulates: gas from furnaces; catalyst fines

� Wastewater

• By-products of process facilities

� Hazardous materials

• Various treatment chemicals

� Wastes

• By-products of process facilities

� Noise

Environmental Hazards

Ahmad Shafaghi

� Personal hazard and environmental hazard are

governed by the government agencies primarily

• US OSHA and EPA

• UK HSE

� International Standards:

• NFPA

• ISO

• Other international standards

� Industry Best Practices

• Use of well established and proven methods

• Use of best technology (e.g., for pollution control)

HSE Hazards Compliance

Ahmad Shafaghi

� Hazards of the facilities that store, process and transport hazardous materials that could pose risk

� Hazardous Materials: flammable, explosive, corrosive and toxic materials

� Process hazard facilities:

• Offshore / onshore drilling rigs

• Offshore / onshore oil and gas production facilities

• Pipelines

• Terminals

• Refineries

• Chemical plants

• Other facilities handle hazardous materials regardless of their sizes

Process Hazards

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Process Hazard Targets

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Process Hazard Impacts

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� Human injuries/fatalities due to exposure to:

• Blast wave

• Thermal radiation

• Toxic chemicals

� Environment damage due to spill of:

• Air pollutants

• Water pollutants

• Earth pollutants

� Structure damage:

• Process and support facility damage

• Plant building damage/collapse

• Public building damage

� Note: Thresholds of harms will be presented in the risk assessment segment

What is Harm?

Ahmad Shafaghi

� Hazard of a facility may be obvious but the ways it is materialized is not necessarily trivial

� Hence systematic methods are required to identify hazardous events (incident scenarios)

� Main methods for process hazards identification are:

• Brainstorming methods:

− Hazard and Operability (HAZOP) Study

− Hazard Identification (HAZID) Study

− What-if Study

• Analytical Methods

− Failure Mode, Effect and Criticality Analysis (FMECA)

− Fault Trees

• Audits

− Safety audits

Process Hazard Analysis

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Process Hazard Analysis Technique -HAZOP Study

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Teamwork

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� It is a team approach

� Multidisciplinary team employed to provide different

perspectives

� It is to stimulate the team member thoughts to generate

ideas

� It is also founded on the idea that quantity breads quality

� To help make the method systematic, a set of

“guidewords” are used to help direct the flow of thoughts

� Nowadays the methods are much more polished than

before

� There are software help perform the studies efficiently

Brainstorming Method

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Brainstorming

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Typical Process Hazard Analysis Flowchart

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Example of Risk Matrix

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� A system contains a hazard

� An initiating event occurs, which could materialize the

hazard (analogues to a virus enters a human)

� The system safeguard try to stop propagation of the

initiating event (analogues to the immune system in the

body)

� Either the safeguard strong enough to prevent the

initiating event cause a dame or it is unable to do so

� An accident happens when the safeguard is unable to

protect the system

Hazardous Event (Scenario) Sequence

Ahmad Shafaghi

� Equipment failure due to:

• Design errors

• Manufacturing defects

• Handling damages

� Human errors

• Design induced errors

• Defective administrative protections (e.g., procedure issues)

• Operator mistakes

� Nature effects

• Earthquakes

• Severe weather (tornados, high winds, lightning, flooding)

• Land slides /liquefaction

Initiating Events of Hazardous Events

Ahmad Shafaghi

Protection Layers & Initiating Event -Simplified

First Protection Layer

Prevent Propagation of IE?

Initiating Event

Yes

Second Protection Layer Prevent

Propagation of IE?

No

Third Protection Layer

Prevent Propagation of IE?

Yes

Yes

Fourth Protection Layer Prevent

Propagation of IE?

No

No

Yes

No

No Event

Process

Disturbances

Controlled

Release

Uncontrolled

Release

Major Incident

Ahmad Shafaghi

� Process Hazard Analysis, e.g., HAZID, HAZOP studies, are carried at the various project design stages, including:• Concept (appraise and select)• Preliminary and detail design

� Other stage of project lifecycle including:• Construction,• Transportation

� The analysis will continue during stages after the design, including:• Commissioning • Operations• Maintenance• Temporary abandonment (emergency shutdown)• Modifications• Decommissioning

Timing of Process Hazard Analysis

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Simplified Project Lifecycle

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� Decision making is a complex process, which is dependent on:

• Size of the investment

• Necessity for the project

� Collective activity (major stakeholders involved)

• Inputs include:

− Cost is an obvious input

− Risk is another main input

− Other inputs include:

♦ Reliability

♦ Constructability

♦ Timeline

� Not all projects are completed

Decision Making at Project Life Cycle Junctions

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Effects of Process Hazard Analysis on Risk at Design Phase

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� The primary results of a Process Hazard Analysis are:

• List of risk ranked action items for the purpose of

upgrading or addition of the protection layers.

• List of scenarios for the Layer of Protection Analysis

(LOPA), which could come from:

− Medium ranked scenarios

− High ranked scenarios

• List of scenarios for the a quantitative risk assessment,

which come from:

− High ranked scenarios

� Secondary results are the valuable knowledge gained by

the team during the study of the facility.

Process Hazard Analysis Outcomes

Ahmad Shafaghi

Final Note

We take risk because of rewards