Hazardous Area Classification (HAC) - Petroleum Storage Tank

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Chapter : Gas & Oil Safety

Hazardous Area Classification (HAC) - Petroleum Storage Tank

Hazardous Area Classification (HAC) for a petroleum storage tank farm involves identifying and classifying areas where flammable gases or vapors may be present and pose a risk of explosion. 

Here's an overview of how to approach Steps for Hazardous Area Classification:

1. Identify Potential Sources of Release:

•  Tanks (vents, fill points, drains)
•  Pumps and associated piping
•  Loading and unloading areas

2. Determine the Extent of Hazardous Zones:

• Zone 0: Continuous presence of explosive atmosphere (typically inside tanks).
• Zone 1: Likely presence of explosive atmosphere under normal operations (near vents, filling points).
• Zone 2: Presence of explosive atmosphere is not likely under normal operations, and if it occurs, it will only be for a short period (further away from sources of release).

3. Create Hazardous Area layout Classification :

• Display the details in diagrams.
• Show the extent of each hazardous zone around the sources of release.

4. Reference Standards:

• IEC 60079 series
• API RP 500 and RP 505
• NFPA 497

Diagram & Display baord  Explanation:

1. Storage Tank

• Zone 0: Inside the tank.
• Zone 1: Around the vents and fill points.
• Zone 2: Surrounding Zone 1, extending outwards as per risk assessment.

2. Pump Area

• Zone 1: Around the pump seals and connections.
• Zone 2: Surrounding Zone 1, typically extending to a few meters.

3. Loading/Unloading Area

• Zone 1: Near loading arms and hoses.
• Zone 2: Surrounding the loading area.

Here's a simplified diagram to illustrate the zones around a storage tank farm:

Detailed Example:

Tank Farm Layout:

• Tanks: Identify and number each tank.
• Pumps: Mark the location and type of each pump.
• Piping: Show the routing of all pipelines.
• Ventilation: Indicate areas with potential gas release.

Additional Considerations:

• Ventilation: Ensure adequate ventilation in classified areas to reduce the risk of flammable atmosphere accumulation.
• Instrumentation: Use certified equipment for hazardous areas.
• Maintenance: Regular inspection and maintenance of the equipment to ensure safety.

For detailed and site-specific diagrams, you might want to consult a professional specializing in HAC. If you have specific dimensions and equipment placements, providing those will help in creating more accurate diagrams.