Asphalt tanks operate under high-temperature (120-180°C) and semi-closed conditions, where improper handling of pressure, ignition sources, or personnel safety can lead to catastrophic accidents—such as tank rupture from overpressure, fire from asphalt vapor ignition, or severe scalds to operators. Industry statistics show that 85% of asphalt tank accidents are caused by non-compliance with basic safety procedures, resulting in average losses of $15,000 per incident (including equipment repair, downtime, and medical costs). This specification focuses on three non-negotiable safety pillars—pressure monitoring, fire & explosion prevention, and personnel protection—detailing step-by-step mandatory procedures, clear judgment standards, and emergency response protocols to ensure zero safety risks during operation.

1. Pressure Monitoring: Mandatory Procedures to Maintain Safe Pressure Ranges

The internal pressure of an asphalt tank is driven by the evaporation of volatile components in heated asphalt and the operation of heating systems. Exceeding the safe pressure limit (0.1-0.15 MPa for most tanks) can cause irreversible tank deformation or even explosion. Pressure monitoring requires a "three-stage check system" (pre-operation, in-operation, post-operation) with strict recording and calibration rules.

1.1 Pre-Operation Pressure System Inspection (10 Minutes Before Startup)

Before activating the heating system, conduct a comprehensive inspection of pressure-related components to ensure they function properly:

Pressure Gauge Validation: Verify that the pressure gauge is within its calibration period (valid for 3 months) and has no physical damage (e.g., cracked glass, bent pointer). Tap the gauge lightly—if the pointer fluctuates by more than 0.01 MPa or fails to return to zero, replace it immediately (do not use uncalibrated gauges, as they can provide false readings).

Pressure Relief Valve Test: Manually lift the relief valve’s test lever for 2-3 seconds—you should hear a steady "hissing" sound of pressure release, and the valve should close tightly without leakage when the lever is released. If the valve is stuck (no sound) or leaks after closing, disassemble it to remove asphalt residues (use a wire brush to clean the valve seat) or replace the valve core (use only manufacturer-approved parts to ensure compatibility).

Vent Pipe Check: Inspect the tank’s vent pipe (diameter ≥ 50mm) for blockages—shine a flashlight into the pipe to check for debris (e.g., leaves, asphalt clumps) and use a flexible steel rod to clear any obstructions. A blocked vent pipe is the leading cause of sudden pressure buildup, so this step is non-negotiable.

1.2 In-Operation Pressure Monitoring (Continuous Tracking)

During heating and asphalt storage, monitor and record pressure at fixed intervals to detect anomalies early:

Regular Pressure Recording: Log the pressure gauge reading every 30 minutes on a dedicated "Pressure Monitoring Log." The normal operating pressure range is 0.02-0.08 MPa; if the pressure rises to 0.1 MPa (early warning threshold), take immediate action:

Turn off the heating system (electric heaters or fuel burners) to stop pressure generation.

Open the manual vent valve (located 1.5 meters above the ground for easy access) halfway—opening it fully can cause rapid pressure drops, leading to asphalt foaming and overflow.

Check the heating system’s temperature controller—if the temperature exceeds 180°C (the point where asphalt volatility increases sharply), adjust it to 160°C to reduce vapor production.

Emergency Pressure Relief: If pressure continues to rise to 0.12 MPa (critical threshold), the pressure relief valve should activate automatically. If it fails to open, manually operate the valve’s emergency handle (red-colored for easy identification) to release pressure. Once pressure drops to 0.06 MPa, close the valve and shut down the system for troubleshooting (e.g., inspecting for blocked heating tubes or malfunctioning temperature sensors).

1.3 Post-Operation Pressure Release (Before Shutdown)

After completing asphalt discharge, do not shut down the system immediately—residual pressure can damage the tank over time:

Gradual Pressure Dissipation: Maintain the tank temperature at 80-100°C for 1 hour to allow volatile components to condense, reducing internal pressure naturally.

Final Pressure Check: Open the vent valve fully and wait until the pressure gauge reads 0 MPa (this takes 15-20 minutes for most tanks). Close the valve only when the gauge confirms zero pressure—leaving residual pressure (even 0.02 MPa) overnight can strain the tank’s welds, leading to long-term fatigue damage.

2. Fire & Explosion Prevention: Mandatory Measures to Eliminate Ignition Risks

Asphalt vapor (generated at temperatures above 120°C) is flammable and can ignite with even a small spark. Fire & explosion prevention requires a "two-layer defense system": eliminating ignition sources and preparing emergency fire-fighting measures to stop fires from spreading.

2.1 Ignition Source Control (Zero Tolerance for Fire Risks)

No-Fire Zone Enforcement: Establish a 10-meter radius "no-fire zone" around the asphalt tank, marked with yellow warning tape and visible signs (e.g., "Danger—No Open Flames, No Smoking"). Install heat detectors and smoke alarms within this zone, set to trigger an alert at 60°C (well below asphalt’s ignition temperature of 230°C). Prohibit all open flames (e.g., lighters, torches) in the zone—conduct random checks of workers’ pockets to ensure compliance.

Electrical Safety Compliance: All electrical equipment in the no-fire zone (e.g., motors, switches, lighting) must be certified as explosion-proof (rating Ex d IIB T4) to prevent sparks from igniting asphalt vapor. Inspect cable connections weekly—look for loose terminals (which generate heat) or cracked insulation (which exposes wires). If an electrical fault occurs (e.g., a motor overheats), turn off the main power switch (located 5 meters away from the tank for safety) and use non-sparking tools (e.g., brass pliers) for repairs—iron tools can create sparks when they hit metal surfaces.

Static Electricity Mitigation: Asphalt flowing through pipes generates static electricity, which can discharge and ignite vapor. Install static grounding clamps on both the tank and the asphalt discharge pipe—connect the clamp to a dedicated grounding rod (copper, 1.5 meters deep in the ground) and check the grounding resistance daily with a tester (must be ≤ 10Ω). When connecting the discharge pipe to a truck or mixer, attach the grounding clamp to the receiving equipment first (before opening the valve) to dissipate static. After discharge, wait 5 minutes before disconnecting the clamp to ensure all static is released.

2.2 Fire-Fighting Preparedness (Immediate Response Capability)

On-Site Fire-Fighting Equipment: Equip the tank area with the following mandatory fire-fighting tools, placed within 3 meters of the tank (no obstacles blocking access):

4kg dry powder fire extinguishers (at least 4 units per tank, suitable for oil fires).

A mobile foam generator (flow rate ≥ 20 L/min) connected to a water source—foam smothers asphalt flames by cutting off oxygen.

A fire blanket (1.5m × 1.5m, heat-resistant to 500°C) for small spills (e.g., asphalt splashes on hot surfaces).

Inspect all equipment monthly: check extinguisher pressure (must be within the green zone), ensure foam generator hoses are not cracked, and verify fire blankets are clean and untorn.

Emergency Fire Response Protocol: If a fire breaks out, follow this mandatory sequence:

Sound the site alarm (pull the red emergency cord located near the tank) to alert all personnel and initiate evacuation (evacuate to a pre-designated assembly area 50 meters away).

For small fires (e.g., asphalt spill on the ground), use a dry powder extinguisher—aim at the base of the flame (not the top) and sweep side to side until the fire is out.

For large fires (e.g., tank surface on fire), activate the foam generator—direct the foam stream to cover the entire tank surface (start from the bottom and move up) to smother the fire.

Call the local fire department (dial emergency services immediately) and provide the tank location, capacity, and type of fire—do not attempt to extinguish large fires alone.