Risk Assessment and Hazard Identification Techniques.pdf

Risk Assessment and Hazard Identification Techniques

1. XÁC ĐỊNH CÁC YẾU TỐ NGUY HIỂM
(HAZID)

2. Agenda
Day 1: Overview of Risk Assessment and Hazard Identification Tech niques 8:30 - 9:00
Introduction
9:00 - 9:30
Definitions and Regulations
9:30 - 10:00
Why Hazard Identification and Risk Assessment ?
10:00 - 10:15
Break
10:15 - 11:00
Risk Management
12:00 - 13:30
Lunch
13:30 - 14:15
Hazard Identification Techniques: Checklist, What-if, Checklist, HAZOP, FTA, ETA
15:30 - 16:30
Case Study
17:00
End day 1

3. Agenda
Day 2: HAZID 8:30 - 10:00
Hazard Identification Techniques: Bow-tie, LOPA, SIL, FMEA, QRA
10:00 - 10:15
Break
10:15 - 12:00
HAZID Scope HAZID
Team of HAZID
HAZID Methodology
12:00 - 13:30 Lunch
13:30 - 15:30HAZID guide word
HAZID worksheet
HAZID Report
15:30 -16:30
Case Study
16:30 -17:00
Q&A
17:00
End

4. Definitions •Hazard is a source of harm
•Hazard-the way in which an object or a situation may cause harm
•Hazardous conditions or situations can cause harm to people, da mage to
property and environment when hazards are not controlled
•Risk-combination of probability of an event &its consequence
ISO/IEC Guide 73
•Incident-a event which Could or Does result in unintended
harm/damage
•Accident-a event which results in unintended harm/damage

5. Typical Incidents •Toxic gas clouds;
•Asphyxiates:
•Fires (jet fires, pool fires, fireballs, flash fires);
•Explosions (VCEs, BLEVEs, mechanical/chemical explosions):
•Hazardous liquid spills:
•Combustible dusts:
•Corrosive substances

6. Industrial Major Inccidens •The Flixboroughdisaster 1974
•Texas City Disaster 1974
•Mexico City 1984
•Bhopal 1984
•Chernobyl 1986
•Piper Alpha 1988
•BP Texas City 2015
•The Macondoblowout 2010

8. Regulatory Development •1985: AIChE forms the Center for Chemical Process Safety (CCPS)
•1990: API - Recommended Practice # 750: Management of Process Ha zards
•1992: OSHA - 29 CFR 1910.1 19: Process Safety Management
•1996: EPA - 40 CFR Part 68: Risk Management Program
•1974 -Health and Safety Executive (HSE) UK
•1999 -Control of Major Accident Hazards (COMAH) regulations UK
•1999 -Control of Substances Hazardous to Health (COSHH) regulat ions
UK
•1982 -Seveso I Directive (Europe)
•1999 -Seveso II Directive

9. Codes & Standards •IEC 61508/IEC 61511
•ANSI/ISA-84.00.01:2014
•ANSI/ISA-84.91.01:2012
•IEC 31010:2019: Risk management — Risk assessment techniques
•API RP 14C
•ISO 10418:2019
•QCVN 11 : 2012/BCT: mức rủi ro chấp nhận được trong đánh giá QR Acho các hoạt
động dầu khí, xăng dầu, hóa chất và nhiệt điện.
•TCVN IEC/ISO 31010:2013 về quản lý rủi ro và kỹ thuật đánh giá rủi ro

15. Hazard Identification Techniques

17. Task risk •Structured analysis of a task
•Breaking down process into detailed steps
•Each part of the sequence is identified what might go wrong
and what can be done to prev ent or mitigate the consequence.
> What are the issues with that steps ?
> What is the order of each step ? (Hierarchy)
> What can do wrong during that step?
> What can prevent or mitigate the effect?
> Should the procedure be modified or abandoned?

18. Advantages Disadvantages •Skilled persons who have experience with
that task.
•Tailored to the individual task and the
requirement of that task.
•Easy to use
•May rely on experience that not relevant for
particular task
•Experience may not be readily available.
•May rely totally on experience and so lose
some structure in the analysis

19. Check list
•A checklist is a list of questions, checks or items on a
particular aspect of the task under consideration
•Customised to requirements of individual applications/
companies.
•Straightforward, structured, easily understood & can ensure
consistency
•Useful for standard or repeated operations to ensure no
basic problem is overlooked.
•Encouraged to add to the list & maintain an open mind
during their use.
•Can be used at any time throughout a design or with an
existing facility.
•Where lack of experienced personnel the use of existing
checklists is a valuable tool for identifying hazards.
•Best used in conjunction with "What If' to get best results
•Require time up-front obtaining data &
information.
•Not thorough enough in many cases since it follows
a non analytical, non interactive methodology.
•May not cover all cases.
•Very dependent on experience of team members.
Dependent on obtaining/creating/using good
checklists.
•The creation of a good checklist requires
considerable expertise and experience
•If the checklist is incomplete due to lack of
experience a fault may be overlooked
•Technique can lead to a ‘blinkered’ study that does
not fully explore hazards associated with process.
•Production and validation can be resource intensive

20. What if •A brainstorming study of experienced persons, familiar with pro cess, ask
questions of their concerns about possible hazards
•What if? is one of the two oldest Hazard Identification Techniq ues.
•What If? can be used at any time for new or existing facilities
•Best results when used with Checklist method.
•Easy to learn and use.
•Disadvantage Much less structured than other methods and can gi ve poor results
unless personnel are . experienced and well prepared.
•Much less structured than other methods
•Can give poor results unless personnel are experienced and well prepared.

21. •Divide facility or unit into nodes relate common functions
•Postulate problems and failures by asking the question "What if ...”
•For each "What if' question record the Consequences & Safeguard s
•For each "What if' question, recommend any Actions needed to
prevent the occurrence or mitigate the consequences.

22. Hazard and Operability Study (HAZOP) •A structured analysis of a system, process or operation, carrie d out by a
multidisciplinary team.
•Used in design and operations to provide a rigorous design inte grity
assurance process
•HAZOP study is one of the most widely used hazard identificatio n methods
within the chemical (and many other) industries
•HAZOP is one of the techniques specifically mentioned in some r egulations

24. •Divide facility into subsystems : NODES
•Nodes are equipment items
•Pressure specification breaks may define node boundaries
•Node can be from SDV to SDV
•Time allowed for HAZOP review of each node is 2 to 4 hours
•If nodes are too small you can loose sense of analysis and incu r
excessive repetition.
•If nodes are too large, hard to handle, becomes confusing
•More than 10 persons are hard to control; 3 persons or less: in put too
limited. Optimal number: 4 to 6

25. HAZOP Guide words

27. •HAZOP for high risk units
•What if + Checklist for formedium risk units
•Checklist for low risk units

28. Fault tree analysis (FTA) •FTA focuses on a particular undesired event and aims to determi ne all
of the ways in which it could occur
•Can be used to identify the root causes of a hazard and
•Used to assess the probability/frequency of the top event
•FTA is often used with consequence modelling in QRA

30. Event Tree Analysia(ETA) •Focus on possible outcomes of an incident that results from a s elected
initiating event.
•Often used with consequence modelling in QRA
•Provides logical graphic of pot ential outcomes from initiating event
•Usually limited to the identification of special hazards.
•Used for examine SIL

32. Bowtie •Visual representation for a hazardous event from the initiating causes
to range of consequences, including the worst-case outcomes.

35. Layer of Protection Analysis (LOPA) •LOPA is an analytical procedure that looks at safeguards on a p rocess plant
to see if the protection provided is adequate for every identif ied hazard.
•LOPA is a semi-quantitative risk analysis methodology
•LOPA is a scenario-driven methodology
•It is based on pre-identified scenarios from studies: HAZOP, Wh at-if study,
MOC or design review. LOPA is then applied to one scenario at a time.
•A scenario is defined by a single cause-consequence pair

40. Methodology •Identify and define scenarios
•Select an incident scenario
•Identify the initiating event of the scenario and determine the initiating
event frequency (events per year)
•Identify the IPLs and estimate the probability of failure on de mand (PFD) of
each IPL
•Estimate the risk of the scenario by the combination of the con sequence, the
initiating event, and IPL data (PFD).

41. •An Independent Protection Layer (IPL) is a safeguard capable of
preventing a scenario from proceeding to its undesired conseque nce

43. Frequency Estimation for LOPA •Guidelines for Process Equipment Reliability Data, CCPS (1986)
•Guide to the Collection and Presentation of Electrical, Electro nic, and
Sensing Component Reliability Data for Nuclear-Power Generating
Stations. IEEE (1984)
•OREDA (Offshore Reliability Data)
•Inherently Safer Chemical Processes: A life Cycle Approach, CCP S (1996)
•Handbook of human Reliability Analysis with Emphasis on Nuclear Power
Plant Applications, Swain, A.D., and H.E. Guttman, (1983)
•Company experience

45. SIL •LOPA
•ETA
•Risk graph

48. •ANSIIISA S84.01 -1996 : Application of Safety Instrumented
Systems for the Process Industries
•IEC 61508 -2000 : Functional safety of electrical / electronic
/programmable electronic safety-related systems
•IEC 61511 -2003 : Functional safety -Safety Instrumented System s
For The Process Industry Sector

51. SIL by Risk Graph

52. FMEA •A FMEA considers possible single failure modes of mechanical an d
electrical equipment
•Consequences & frequency of each failure are identified and rec orded
•An FMEA on engineering item is equivalent of a HAZOP study of a P&ID
•Useful in investigation of incidents or in the analysis of a ne w design
•Very good for analyzing complex equipment items : compressors
•To obtain data for quantitative risk analysis (QRA)
•Widely used in the nuclear industry
•Needs to be used with Fault Tree Analysis to broaden scope.

53. Methodology 1. Select system and split into subsystems
2. Postulate a failure mode of the subsystem
3. List the effects of failure of that subsystem
4. List safeguards that might prevent or mitigate effects of fai lure
5. Use risk matrix to determine severity and likelihood of failu re
6. Recommend remedial actions (if needed)

54. HAZID •A systematic review of possible causes and consequences of haza rdous
events and attempt to mitigate them
•HAZID is conducted by a multi-disciplinary team
•HAZID originated from HAZOP

55. Objectives
•Structured review techniques to identify all hazards associated concept,
design, operation or activity, including likely causes and poss ible
consequences or safeguards (ISO17776)
•Identify primary hazard management controls including:
-Prevention; -Detection; -Ignition; -Control; -Mitigation; -Es cape and;
-Evacuation
•Rank all hazards in terms of frequency and consequence using ri sk matrix.
•Propose recommendations to eliminate, prevent, control or mitig ate hazards
•All hazards identified is recorded as Hazard Register for the f acilities

56. HAZID Methodology

60. HAZID Team Mandatory •Facilitator
•Scribe
•Process Engineer
•Project Engineer
•Safety Engineer
•Operation Engineer
Optional •Mechanical Engineer
•Civil Engineer
•Fire protection Engineer
•Chemist
•Structure Engineer
The team content will change fro m day to day but too frequent
changes must be avoided

61. Data for HAZID •Plot Plans with elevations
•Equipment layout
•Escape Route Drawings
•Process Flow Diagram
•Process condition: P, T, F, Composition, capacity, …
•Materials Hazards Data Sheets
•Materials of Construction
•Protective Systems - passive and active
•Procedures
•Operating/control/shutdown philosophies/procedures;

62. Nodes in HAZID •Specific process units or Sections of an operation or design
•Individual pieces of equipment and piping as in a HAZOP
•Steps of an operation or activity
•aHAZID sessions should not last more than eight hours per day

63. HAZID Guide words •ISO 17776-2002 Guidelines on tools and techniques for hazard
identification and risk assessment, 2002
•DNV offshore HAZID guide words
•PB recommended HAZID guide words

67. HAZID Report •Objective
•Scope
•Methodology
- HAZID Method Overview
-Assumptions
- Nodes
- Risk ranking
-Workshop Recording and Reporting
-Agenda and Participants
•Finding and Recommendations
•Attachments
- HAZID Workshop Assumptions
- Risk Matrix
-Worksheets
- Participant sign

68. HAZID Worksheet

69. Benefits of HAZID •Early identification of high consequence hazards providing esse ntial input
to project development decisions before the design reaches its final stages
•Lead to safer and more cost-effective design options
•Provide a clear basis for major accident event screening as pas t of formal
assessment studies
•Fits in very well to the abandonment and demolition of process plant.
•Produce novel options for change.
•Flexible and can be used at different phases of a project
•Utilisesthe experiences of operational staff.
•Identify low-frequency high-impact events and so fits in well w ith QRA.

70. Disadvantages •The study is mentally exhausting.
•Team structure may have to change during the study process.
•Timing of the arrival of new member and the departure of ones
•Its benefits depend on experience of leader and knowledge of th e team
•Guidewords are an important element of a HAZID, and should be
sufficiently comprehensive
•Generation of the guidewords may omit a significant event
•The success is dependent on the skills of the team