Hazardous Area Classification - saflameproof.org.za
Transcript of Hazardous Area Classification - saflameproof.org.za
Hazardous Area Classification
Schalk J. P. Kruger
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Agenda
• Legislation
• Scope of Work (SOW)
• HAC team
• Chemicals
• Operating conditions
• Method/s of HAC
• HAC study
• HAC drawings
• Practical
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Legislation
Constitution
Rights
ACTs
Who and Why
Regulations
What
Standards
How
• Your right to be safe
• Employer, employee - safety
• Regulation of the things
• Specific procedure on the how
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Scope
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Team
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Chemicals - Flammability
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Chemicals - Flammability – SDS - Methanol
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Chemicals - Classification – Standard - Methanol
SANS 60079-20-1: Material characteristics for gas and vapour classification — Test methods and data
Gas Group: IIA
Auto Ignition Temperature (AIT): 440 oC
Temp class: T2
LEL: 6%
Flash point: 9 oC
Relative Density: 1.11
X
Zone
IIA
T2
X
Zone Distance
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Chemicals – Compositions! (VL-Bottoms)
Chemical Vol. % Relative
Density
AIT oC Flash
Point oC
LEL % Group
(MESG)
Propanal (C3H6O) 39% 2.00 188 -26 2.0% IIB (0.86)
Butanal (C4H8O) 21% 2.50 205 75 1.7% IIA (0.92)
Water (H2O) 14% 0.017 N/A N/A N/A N/A
Ethyl Acetate (C4H8O2) 9% 3.04 470 -4 2.0% IIA (0.99)
2-Methyl Propanal (C4H8O) 5% 2.50 165 -22 1.6% IIA (0.92)
2-Methyl Butanal (C5H10O) 1% 2.97 240 -5 1.3% IIC (H10)?
3-Methyl Butanal (C5H10O) 1% 2.96 207 -5 1.3% IIA (0.98)
Ethanal (CH3CHO) 1% 1.52 155 -38 4.0% IIA (0.92)
Result (Inference) >1 165 (T1) -26 1.6% IIB (39%)
Calculated 1.97 165 (T1) 2.093% IIB (0.87)
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Area Classification - Direct Example
SANS 10089-2: Electrical and other
installations in the distribution and marketing
sector
• American Petroleum
Institute (API) – API RP
500: Petroleum Facilities
• Energy Institute – IP15:
Flammable liquids
IIA
T2
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Area Classification - Direct Example Challenges
A - Pump Rate, flashback
arrestor, safety release
valve, operational
conditions, ambient
temperature changes
B - Relative density
C - Relative density, liquid
leaks, sampling flushing
D - Lots of applications i.e.
Zone 1, over classification
E - Only for these
chemicals
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Source of Release - Operating Conditions - PFD
Major vessels, major process streams,
pressure, temperature, composition, flow
directions
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Source of Release - Sources of Release - MFD
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Area Classification - Grades of Release
Equipment Example of Leak Grade of Release
Pumps Seal Secondary
Compressors Seal S
Vents Full Bore Primary
Valves Gland/Seal S
Pressure relief valves Full Bore P
Small bore connections Fitting Leak S
Piping systems Gasket S
Flanges, blinds Gasket S
Pig receivers and launchers Full bore or Partial Release P
Liquid pools Vaporisation Continuous
Sumps Vaporisation C
Drains (Open) Vaporisation C
Drain Points Full bore or Partial Release P
Sample points Full bore or Partial Release P
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Area Classification – Degree of Ventilation
Ventilation
Grade of
release
Degree
High Medium Low
Availability
Good Fair Poor Good Fair PoorGood, fair or
poor
Continuous
(Zone 0 NE)
Non-
hazardous a
(Zone 0 NE)
Zone 2a
(Zone 0 NE)
Zone 1aZone 0
Zone 0
+
Zone 2
Zone 0
+
Zone 1
Zone 0
Primary
(Zone 1 NE)
Non-
hazardous a
(Zone 1 NE)
Zone 2 a
(Zone 1 NE)
Zone 2aZone 1
Zone 1
+
Zone 2
Zone 1
+
Zone 2
Zone 1 or
zone 0c
Secondary b
(Zone 2 NE)
Non-
hazardous a
(Zone 2 NE)
Non-
hazardous a
Zone 2 Zone 2 Zone 2 Zone 2Zone 1 and
even zone 0c
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Area Classification - Zones
• Zone 0: Continuous release - All the time
• Zone 1: Primary release - During normal
operations
• Zone 2: Secondary release - During
abnormal operations
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Source of Release - Dispersion Liquid / Vapour
Dispersion: PHAST Pamphlet from Det Norske
Veritas (DNV)
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Source of Release - Dispersion Equations
Witlox, H W M and Holt, A 1999, A unified model for jet, heavy and passive dispersion
including droplet rainout and re-evaporation, Det Norska Veritas, London UK
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Source of Release - Dispersion – CFD
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Source of Release - Dispersion - Concentration
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Source of Release – Meteorological conditions
• Solar Radiation
• Evaporation
• Precipitation
• Wind speed, height and direction
• Relative humidity
• Barometric pressure
• Topography
• Ambient air temperature
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Area Classification - Dispersion – Pool Heat
Transfer
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Area Classification - Dispersion –
Meteorological Conditions - Wind
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Area Classification - Dispersion - Other
• Congestion of SORs
• Obstacles to dispersion
• Enclosed spaces i.e. trapping of dispersion
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Study
• Traceable i.e. references, calculations, reproducible
• Approved by accountable persons
• Defendable arguments
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Drawings
• Top view
• Side views
• Cuts
• Different levels of structures
• Chemical products table
• SOR table (Zones 0 and 1 only and perimeter zone 2)
• Approvals
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Dispersion Shapes - Standard
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Area Classification results - Direct Example
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Area Classification Result - Source of Release
Method
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Area Classification - Scenarios
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Area Classification - Scenarios
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Conclusion
Legislative compliance provides a safe and controlled environment.
Area Classification provides the basis for a number of actions e.g.
permit to work controls, selection of equipment and inspections
“Hazardous Area Classification” is a statement that expresses an action.