Hazop Introduction
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Transcript of Hazop Introduction
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HAZOP STUDY
HAZard and OPerability
An introduction
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Jan. 2012 Process Safety Training Fluor 2
Content
History
Purpose
Hazards
Deviations
Parameters
Guidewords Consequences
Safeguards
Application
HAZOP in Dow
HAZOP Process
Nodes
Starting the Study
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Jan. 2012 Process Safety Training Fluor 3
Origins of HAZOP
Concept dreamed up by Bert Lawley atI.C.I. in the late 1960s
Result of a desire to have structured
check on P. & I.D.s Spread through I.C.I. in early 1970s
Endorsed by the Health and Safety
Directorate of the U.K. government Dow started to use in mid 1970s
NL, Belgian and U.K. government
adopted HAZOP
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Jan. 2012 Process Safety Training Fluor 4
HAZOP in the 1980s
U.K. HSE and the Dutch
Arbeidsinspectie began to mandate
HAZOP as part of Safety Report for
Seveso Directive
I.C.I. by this time were doing HAZOP
on everything
Dow incorporated in its Risk
Management process based on its own
criteria (focusing on highest risk)
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Purpose of HAZOP
To identify credible causes, consequencesand safeguards before INCIDENTS occur
To define recommendations to minimize theHAZARD by eliminating or controlling thecause or providing lines of defence
Provide compatible information forsubsequent Process Safety efforts (i.e.
LOPA scenarios) Comply with regulatory Process Safety
requirements
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Jan. 2012 Process Safety Training Fluor 6
Scope of HAZOP
Review is limited to the piping,instrumentation and equipment shown onthe P&IDs (do not re-design)
Review is limited to deviations from normaloperations
Impact of process unit on the utility systemsor other process units will be noted as
requiring further study Primary intent is to identify hazards and
define action items for additional safeguardsif appropriate
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Jan. 2012 Process Safety Training Fluor 7
HAZARDS
Fire and Explosion
Reactive Chemicals Incidents
Toxic Exposure
Corrosion
Radiation Vibration
Mechanical Hazards
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Jan. 2012 Process Safety Training Fluor 8
Deviations
Hazards are caused by DEVIATIONS
from the DESIGN INTENTION
HAZOP is a method for generatingthese DEVIATIONS using GUIDE
WORDS
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Study is based on
PARAMETERS
Flow
Temperature
Pressure
Level
Composition Agitation
Anything it is important to control
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Jan. 2012 Process Safety Training Fluor 10
In combination with GUIDE
WORDS
No
Less
More
Reverse
Instead of or Other than (e.g.something else or wrong composition)
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Jan. 2012 Process Safety Training Fluor 11
Combinations of parameters and
guide words are DEVIATIONS
No flow
Less flow
More flow Reverse flow
Flow of something not planned
More temperature
Less temperature
And so on...
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Jan. 2012 Process Safety Training Fluor 12
Deviations are logical
combinations like...
More temperature
Less pressure
Ignore illogical combinations like.
X Reverse temperature
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Jan. 2012 Process Safety Training Fluor 13
Determining the causes for a
deviation
Consider only the causes that originate within the node(consequences may be outside of the node)
Deviations could be caused by: Equipment or process control failure
Human error
Loss of utilities
External events such as fire
Long term processes, e.g. erosion, corrosion, coking
If process instrumentation crosses a node boundary, controlmalfunction is considered a cause in both nodes
Deviations that require the simultaneous occurrence of two ormore unrelated causes are not considered
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Jan. 2012 Process Safety Training Fluor 14
Consequences
Describe all consequences, even those that propagate outsidethe node.
Consequences may include: Personnel injury
Environmental damage Equipment damage
Property loss
Extended downtime
Operability/Quality problems
Consequences are described assuming there are no
safeguards Describe consequences as a chronological sequence of
events
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Jan. 2012 Process Safety Training Fluor 15
Safeguards
Safeguards may include: Equipment design
Instrumentation (control, alarm and shutdown)
Pressure relief devices Administrative procedures
Only list those instrument systems that have at leastan alarm as a safeguard
Control instrumentation must automatically corrector mitigate a process deviation
Operator training and administrative proceduresshould be listed provided they are part of ODMS
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what can HAZOP be applied
to?
Continuous processes
Batch procsses
Operating procedures (similar concept
to Job Safety Analysis)
Maintenance procedures
Any operation where the Design
Intention is defined and deviations are
possible
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Jan. 2012 Process Safety Training Fluor 17
Recommendations
Recommendations are made to: Eliminate a cause
Prevent or mitigate the consequence
Reduce the likelyhood that the hazard will occur
Examples of recommendations include: Equipment/instrumentation changes/additions
Further study needed
Inspection and maintenance
Training Administrative systems to manage hazards
Verification of design assumptions
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Jan. 2012 Process Safety Training Fluor 18
Risk Review in DOW today(Process Risk Management Standard 2001)
Level 1 Risk Review: (Process Hazard
Analysis (RC-PHA, Fire and Explosion
Index, Chemical Exposure Index,LOPA target factors)
Level 2: LOPA, Cause Consequence
Pairs, Occupied Building Overpressureanalysis
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Risk review in DOW today
LEVEL 1
Fire and Explosion Index < 128
Chemical Exposure Index < 200 CEI Hazard Distance (3) outside of the
fence
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Jan. 2012 Process Safety Training Fluor 20
What makes HAZOP
mandatory?
TECHNOLOGY IS NEW TO DOW
New processes
New chemistry
New Unit Operations
These are the ONLY criteria for
Mandatory HAZOP
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Jan. 2012 Process Safety Training Fluor 21
HAZOP method
Generic for Chemical Industry
Dow guideline setting down our special
needs (\\USN17\ehsaps)
Based on P.& I.D. or flowsheet study
with Operating Instructions/Design
Intention
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Jan. 2012 Process Safety Training Fluor 22
Normal scope of a Dow
HAZOP
Based on the operating unit(s)
generating the highest risk
Basic Criteria described All stepsfrom start up, through normal running
to shut down
Application to Most EffectiveTechnology (M.E.T.)
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HAZOP Process
Team maximum 6 persons from (example):
run plant engineer
programmer process control
process chemist
shift operations team member study leader/facilitator
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Jan. 2012 Process Safety Training Fluor 24
Nodes P&IDs for the process are broken into manageable
sections called nodes
Nodes generally consists of unit operations andassociated piping and connect to upstream and
downstream units Nodes are defined by the HAZOP team and can be
redefined as needed
A Global issues node can be included to capturehazardous events that can impact the entire process
unit. For example:Loss of containment
Sampling
Utility failure
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Jan. 2012 Process Safety Training Fluor 25
Typical nodes
E 201
R 201
P 201
NODE 1
NODE 2
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Jan. 2012 Process Safety Training Fluor 26
Nodes
There is no right way to define nodes
Usually start with a small node
As experience builds, move to a larger node Follow the leaders intuition
If the team gets bored, the node is probably
too small If the team gets confused, the node is
probably too big
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Jan. 2012 Process Safety Training Fluor 27
Starting the study:
The most knowledgeable person
describes the INTENTION of the node
Composition (which chemicals are in
the equipment)
Flow, temperature, pressure, phase,
quantity, agitation etc
. Anything important to the process
Leader records for study team
reference
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Jan. 2012 Process Safety Training Fluor 28
Start with Deviation No Flow
Team gives all the causes for no flow in thelines and equipment inside the node
Leader prompts their thinking
Team can add but not delete These causes are recorded in software
package
The library in the software can be consulted
for possible additional causes When the ideas dry up move on to
CONSEQUENCES
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Team decision on ACTION
column Team may decide if any new action is
needed
Can record any protective devices or
alarms which become active e.g. PSVs Can refer decision outside the team
Can refer serious consequences for
consequence analysis
MUST NOT REDESIGN THE PLANT in
the Hazop study session!!
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Jan. 2012 Process Safety Training Fluor 30
After no flow
Repeat exercise for less flow
(ususally similar to no flow
Repeat exercise for more flow
Repeat exercise for reverse flow
Repeat exercise for composition
(other than expected materialcomposition)
UNTIL FLOW is completely studied
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Jan. 2012 Process Safety Training Fluor 31
After flow
List causes for more temperature
proceed to consequences for more
temperature
repeat all steps as for flow
when temperature is studied, go to
pressure
after pressure, consider other
parameters, e.g. agitation (use design
intention as a guide)
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Jan. 2012 Process Safety Training Fluor 32
When parameters are all done
for node 1
Repeat whole process for node 2
And all the other nodes defined in the
study scope
List actions and responsibility for follow
up