ATEX 1999/92/EC (Borehole Directive 92/91/EEC) PROCESS SAFETY ASPECTS

Transcription

1 ATEX 1999/92/EC (Borehole Directive 92/91/EEC) PROCESS SAFETY ASPECTS

2 ATEX 1999/92/EC QUOTE, ARTICLE 3 protection against explosions, following basic principles: - Avoid leaks / avoid mixing with air - Avoid ignition - Avoid Escalation - Or: Handle / process below flash point - (Inherently safer principle) - Ensure escape/evacuation is possible

3 Directive 92/91/EEC, Borehole Directive QUOTE, ARTICLE part C, para 1.1 Part C, para 1.1: to limit the spread of accidents and to allow efficient and controlled evacuation of the workplace in emergency situations - Avoid leaks / avoid mixing with air - Avoid ignition - Avoid Escalation - Or: Handle / process below flash point - (Inherently safer principle) - Ensure escape/evacuation is possible

4 PIPER ALPHA, PROCESS SAFETY WHERE EVERYTHING WENT WRONG Leak on gas condensate pump Leak ignited causing initial explosion Firewater not available (locked-out due to diver operations) Firewalls not rated for explosion, spread to other fire zones Further leaks of oil & condensate in neighbouring fire zones Smoke & heat prevented escape and evacuation Fire damaged 3 pressurized gas risers - burst (incoming pipelines) No hope 163 people killed Link

5 WHAT IS PROCESS SAFETY? PROCESS SAFETY AND OCCUPATIONAL Process safety is the multidisciplinary activities to manage the integrity of hazardous operating systems, applying: Good design principles Sound Engineering Practices Safe operating Practices Occupational Safety High frequency, low severity accidents (slips, trips, falls) Process Safety Low frequency, high severity accidents (fire, explosions, etc) 5

6 OTHER NAMES OR EQUIVALENTS Loss prevention Technical Safety

7 ELEMENTS OF PROCESS SAFETY Process Design Process Control Isolation & Valving Philosophy Inherently Safer/ Design ESD Overpressure Protection Human Factors / Alarm Management Fire & Gas Detection Facility Layout Containment / Integrity Active Fire Protection Escape, Evacuation, Rescue Ignition Control Passive Fire Protection

8 PSM PROCESS SAFETY MANAGEMENT Design Procurement / Construction Completion (MC / Precommiss) MOC Management of Change Manning / Competencies Operation / Maintenance Process Safety Management

9 DESIGN PRIMARY AND SECONDARY FEATURES Primary methods attack the fire triangle Secondary methods mitigate the consequences of fire/explosion Tertiary measures are to ensure safe evacuation and rescue

10 BARRIERS / LAYERS OF PROTECTION

11 BARRIERS / LAYERS OF PROTECTION COMMUNITY EMERGENCY RESPONSE PLANT EMERGENCY RESPONSE FIRE AND GAS SYSTEMS Deluge systems, fire sprinklers, toxic gas detection and alarms PHYSICAL BARRIERS Barricades, Dikes Risk = MITIGATION Pressure Relief Valves Rupture Disks PREVENTION Safety Critical process Alarms Safety Instrumental Systems CONTROL Basic process Control Systems Process Alarms, Operating Procedures Operator Supervisor PROCESS DESIGN Inherently Safer Design Probability x Consequence Role of barrier: Reduce the probability of a hazard

12 CONTAINMENT / INTEGRITY - DESIGN Materials Selection Philosophy/Strategy Piping Classes / pipe specs incl. gaskets Flanging strategy Valve selection strategy Design criteria for small bore piping/tubing and vibrating pipework Proper pipe support design Clear selection strategy for shaft seal selection

13 CONTAINMENT / INTEGRITY MATERIAL SELECTION Evaluate both internal and external corrosion risks Design Life time Fluid Composition - ph / Environment H 2 S CO 2 H 2 O Chlorides Pressure Temperature 13

14 CONTAINMENT / INTEGRITY MATERIAL SELECTION TYPICAL MATERIALS FOR OIL&GAS PROCESS / UTILITY SYSTEMS Carbon Steel Internal Coating / Cladding FBE Composite (Chesterton) CRA cladding CRA Corrosion Resistant Alloys SS Gr. 2 Titanium Cupper Alloy External coating UNS R50400 TSA: Thermally Sprayed Alu. 90/10 Kunifer Tungum Nickel Alloy A105 A106 CS A333 A350 LTCS Austenitic 316 / 316L SMO 254 AISI 316 AISI 316L UNS / UNS UNS S31254 Non-Metallic Duplex - Austenitic-Ferritic 22% Cr Duplex SS UNS S % Cr Super Duplex SS UNS S32750 UNS S32760 UNS C70600 Inconel 625 UNS N % Cr Hyper Duplex SS New material under development - Sandvik UNS C69100 Hastelloy C-276 UNS N10276 GRE Glass fibre reinforced epoxy GRP Glass fibre reinforced polyester 14

15 CONTAINMENT / INTEGRITY MATERIAL SELECTION 15

16 CONTAINMENT / INTEGRITY FLANGING STRATEGY Flanges versus fully welded piping Selection of Inherently safer flanges Some flange types will not result in area classification and are fire safe.

17 CONTAINMENT / INTEGRITY VALVE SELECTION

18 CONTAINMENT / INTEGRITY PIPE SUPPORTING

19 CONTAINMENT / INTEGRITY FABRICATION Materials as specified (3.1 certificates) (Verification of certificates PMI, hardness tests, etc.) Welding to approved welding procedures + certified welders Traceability to materials, WPS, welders Fabrication tolerances + dimensional checks QC NDT Pressure tests 19

20 CONTAINMENT / INTEGRITY MC/PRE COMMISSIONING P&ID checks Check of pipe supports / release of spring supports Flange tightening procedures / torque / Traceability labels Pressure / Leak tests Etc. 20

21 CONTAINMENT / INSERVICE INTEGRITY Pressure equipment / In- / external inspections Periodic inspections/tests as per Authority requirements PSV re-calibration / re-certification RBI (API 580, API 581, DNV RP-G101) FFS (Fitness for service) evaluation (ASME FFS-1, API 579) Line walks Etc. CUI (Corrosion under insulation) Galvanic corrosion 21

22 LAYOUT - ARRANGEMENT Separate process / utility areas/equipment Clear hazard gradient Use prevailing wind direction Separate release sources from ignition sources Flare located up-upwind Avoid congestion Avoid confinement/blocking Layout to follow the process flow logically understand right way (example next slide)

23 LAYOUT ARRANGEMENT Flare lines well protected, sloping towards flare drum Avoid gas turbines and fired heaters in classified area. Gas compressor at higher level than suction drum and after cooler. Anti-surge valve over compressor level. Vessels with liquids at low level Equipment with high pressure gas at high level (link - BLEVE)

24 LAYOUT ARRANGEMENT. HAZARD GRADIENT Prevailing Wind Direction Risk Pressure Inventory Leak freq. Distance 24

25 LAYOUT ARRANGEMENT. HAZARD GRADIENT Accommodation Separation Risers Risk Pressure Utility Compression Wellhead Inventory Distance 25

26 LAYOUT ARRANGEMENT. HAZARD GRADIENT 26

27 LAYOUT ARRANGEMENT. HAZARD GRADIENT 27

28 ONSHORE - LAYOUT / ARRANGEMENT IRI IM 2.5.2, Oil and chemical plant layout and spacing. CCPS, Guidelines for Facility Siting and Layout. NFPA 30, Flammable and combustible liquids Code BEK 28, Tekniske forskrifter for brandfarlige væsker. BEK 1444, Tekniske forskrifter for gasser 28

29 ONSHORE - LAYOUT / ARRANGEMENT 29

30 ONSHORE - LAYOUT / ARRANGEMENT 30

31 LAYOUT - ARRANGEMENT Dust explosion spray dryer in enclosed building. Building severely damaged (high explosion pressure) Gas explosion compressor in semi-open module with louvres. No damage to main parts (low explosion pressure) Ignition: Static electricity Hot surfaces (gas turbine)

32 EXPLOSION - BUNCEFIELD On December 11, 2005 a number of explosions occurred at Buncefield Oil Storage Depot, Hemel Hempstead, Hertfordshire. During night a gasoline tank was overfilled. Vapours ignited / exploded. At least one of the initial explosions was of massive proportions and there was a large fire, engulfing a large part of the site. The fire burned for several days, destroying most of the site and emitting large clouds of black smoke into the atmosphere. 32

33 EXPLOSION - BUNCEFIELD Significant damage to both commercial and residential properties in the vicinity. 20 tanks totally destroyed. A large area around the site was evacuated on emergency service advice. > 40 people were injured; no fatalities. 33

34 PROCESS SAFETY EXPLOSION - BUNCEFIELD 34

35 EXPLOSION - BUNCEFIELD 35

36 EXPLOSION - BUNCEFIELD 36

37 EXPLOSION - BUNCEFIELD 37

38 EXPLOSION - BUNCEFIELD - CONCLUSIONS Overfilling due to faulty level safety circuit; too few barriers with too weak strength (ref. Functional Safety). Gasoline vapours (more than 30 tons of vapour) ignited off site. The very high explosion pressures (> 1 bar) was caused by congestion from trees in the area. Escalation to neighbouring tanks (Link) The high explosion pressures were confirmed by both CFD calculations and scale tests. This confirmed the theory about the trees 38

39 EXPLOSION - IMPLOSION Implosion is also a hazard And it is also about site selection. (Link Lake Pigneour) 39

40 THANK YOU 40