Hazardous Area Classification. Schalk J. P. Kruger

Transcription

1 Hazardous Area Classification Schalk J. P. Kruger

2 Agenda Legislation Scope of Work (SOW) HAC team Chemicals Operating conditions Method/s of HAC HAC study HAC drawings Practical 2

3 Legislation Constitution Rights Your right to be safe ACTs Who and Why Employer, employee - safety Regulations What Regulation of the things Standards How Specific procedure on the how 3

4 Scope 4

5 Team 5

6 Chemicals - Flammability 6

7 Chemicals - Flammability SDS - Methanol 7

8 Chemicals - Classification Standard - Methanol SANS : Material characteristics for gas and vapour classification Test methods and data Gas Group: IIA Auto Ignition Temperature (AIT): 440 o C Temp class: T2 LEL: 6% Flash point: 9 o C Relative Density: 1.11 X Zone Distance X Zone IIA T2 8

9 Chemicals Compositions! (VL-Bottoms) Chemical Vol. % Relative Density AIT o C Flash Point o C LEL % Group (MESG) Propanal (C 3 H 6 O) 39% % IIB (0.86) Butanal (C 4 H 8 O) 21% % IIA (0.92) Water (H 2 O) 14% N/A N/A N/A N/A Ethyl Acetate (C 4 H 8 O 2 ) 9% % IIA (0.99) 2-Methyl Propanal (C 4 H 8 O) 5% % IIA (0.92) 2-Methyl Butanal (C 5 H 10 O) 1% % IIC (H 10 )? 3-Methyl Butanal (C5H 10 O) 1% % IIA (0.98) Ethanal (CH 3 CHO) 1% % IIA (0.92) Result (Inference) >1 165 (T1) % IIB (39%) Calculated (T1) 2.093% IIB (0.87) 9

10 Area Classification - Direct Example SANS : Electrical and other installations in the distribution and marketing sector IIA T2 American Petroleum Institute (API) API RP 500: Petroleum Facilities Energy Institute IP15: Flammable liquids 10

11 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 11

12 Source of Release - Operating Conditions - PFD Major vessels, major process streams, pressure, temperature, composition, flow directions 12

13 Source of Release - Sources of Release - MFD 13

14 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 14

15 Area Classification Degree of Ventilation Ventilation Grade of release Continuous Primary Secondary b Degree High Medium Low Availability Good Fair Poor Good Fair Poor (Zone 0 NE) Nonhazardous a (Zone 1 NE) Nonhazardous a (Zone 2 NE) Nonhazardous a (Zone 0 NE) Zone 2 a (Zone 1 NE) Zone 2 a (Zone 2 NE) (Zone 0 NE) Zone 0 Zone 1 a (Zone 1 NE) Zone 1 Zone 2 a Zone 0 + Zone 2 Zone 1 + Zone 2 Zone 0 + Zone 1 Zone 1 + Zone 2 Nonhazardous Zone 2 Zone 2 Zone 2 Zone 2 a Good, fair or poor Zone 0 Zone 1 or zone 0 c Zone 1 and even zone 0 c 15

16 Area Classification - Zones Zone 0: Continuous release - All the time Zone 1: Primary release - During normal operations Zone 2: Secondary release - During abnormal operations 16

17 Source of Release - Dispersion Liquid / Vapour Dispersion: PHAST Pamphlet from Det Norske Veritas (DNV) 17

18 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 18

19 Source of Release - Dispersion CFD 19

20 Source of Release - Dispersion - Concentration 20

21 Source of Release Meteorological conditions Solar Radiation Evaporation Precipitation Wind speed, height and direction Relative humidity Barometric pressure Topography Ambient air temperature 21

22 Area Classification - Dispersion Pool Heat Transfer 22

23 Area Classification - Dispersion Meteorological Conditions - Wind 23

24 Area Classification - Dispersion - Other Congestion of SORs Obstacles to dispersion Enclosed spaces i.e. trapping of dispersion 24

25 Study Traceable i.e. references, calculations, reproducible Approved by accountable persons Defendable arguments 25

26 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 26

27 Dispersion Shapes - Standard 27

28 Area Classification results - Direct Example 28

29 Area Classification Result - Source of Release Method 29

30 Area Classification - Scenarios 30

31 Area Classification - Scenarios 31

32 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. 32