Cast Aluminum Safety Manhole Cover Assembly for Petroleum Tank Trucks

RKG Series Cast Aluminum Manhole Covers – Reliable Top-Mounted Safety Solution

RKG Series manhole covers are essential top-mounted components for petroleum tank trucks, chemical tankers, and other hazardous liquid transport vehicles. These covers provide secure access for loading, unloading, and ventilation while maintaining tank safety under normal operations and emergency conditions.

Equipped with a vacuum-pressure vent valve and an emergency relief valve, the manhole cover ensures that under typical conditions, the vent valve remains closed. During fuel transfer or temperature fluctuations, internal tank pressure changes, prompting the vent valve to automatically release or intake air to maintain safe operating pressure. In emergency situations, such as fire or sudden impact, the emergency relief valve opens immediately to release excess pressure, preventing explosions and other hazards.

Global Terminology Variations
This type of tank top safety device is referred to differently around the world:
Germany: “Tankdeckel aus Aluminium mit Sicherheitsventil”
France: “Couvercle de trappe en aluminium avec soupape de sécurité”
Italy: “Coperchio uomo in alluminio con valvola di sicurezza”
Spain: “Tapa de registro de aluminio con válvula de seguridad”
Netherlands: “Aluminium tankluik met veiligheidsklep”
UK: “Aluminum Manhole Cover with Emergency Relief Valve”

In Asia and South America, it is commonly called a “Cast Aluminum Tank Top Lid,” “Petroleum Manhole Assembly,” or “Safety Vent Manhole Cover.” Despite these variations, the primary function remains consistent: protecting the tank and ensuring safe operation.

Key Features
Durable Cast Aluminum Construction: The large and small plates are die-cast aluminum with surface oxidation treatment, providing excellent corrosion resistance and durability.
Optional Dual Vent Configuration: Can be fitted with two vent valves according to operational requirements.
Compact and Cost-Effective Design: Efficient dimensions and lower manufacturing costs make it ideal for commercial tank trucks.
Customizable Openings: Large plate has two pre-drilled holes for optional installation of optic sensors, dip tubes, or external vacuum valves.
Materials: Lever made of galvanized carbon steel; emergency exhaust valve of aluminum alloy; seal rings available in Buna-N or Viton for chemical resistance.

Technical Specifications
Vent discharge setting pressure: 6–12 kPa
Negative opening pressure: -2 to -4 kPa
Emergency exhaust valve pressure: 21–32 kPa
Operating temperature: -20°C to +50°C

Ordering Specifications
Name Model Outer Diameter Center Bolt Hole Distance Bolt Hole Qty
Manhole Cover RKG-L-B460 460 mm 432 mm 12 (11 mm diameter)
Manhole Cover RKG-L-B560 560 mm 530 mm 24 (11 mm diameter)
Manhole Cover RKG-L-B580 580 mm 542 mm 24 (11 mm diameter)

Applications
The RKG cast aluminum manhole cover series is widely used for petroleum transport, chemical liquid tankers, water tankers, and other top-mounted tank access solutions. Its reliable construction, safety features, and international standard compliance make it a trusted choice for operators in Europe, Asia, and South America.