OPW 634 Series 4 in. Tight-Fill Top-Seal Metal Cap

Secure Your Fuel Storage with OPW 634TT Heavy-Duty Metal Caps

The OPW 634TT-4000 is a rugged, 4-inch tight-fill top-seal cap engineered to protect underground storage tanks from environmental contamination and hazardous vapor loss. Constructed with a black powder-coated die-cast zinc body, this metal cap offers superior durability and corrosion resistance compared to standard composite alternatives. It is specifically designed to mate with 4" OPW adaptors (including the 633T, 633TE, 61SA, 633TC & 633TCP models) ensuring a precise fit for critical fuel delivery points.

To maintain a maintenance-free service life in harsh industrial environments, the 634TT is made from high-grade materials that resist oxidation and mechanical wear. The design features a Duratuff® toggle lever and stainless steel pins that distribute uniform downward pressure across the Nitrile (Buna-N) gasket, creating a reliable water and vapor-tight seal.

• Materials: Die-cast zinc body (powder coated), Duratuff® lever, and stainless steel pins.
• Sealing Power: High-performance Nitrile gasket prevents gasoline vapor escape and blocks water/debris entry.
• Security: Integrated design allows for locking with a standard padlock or wire seal to prevent unauthorized access.
• Compatibility: Fits all standard 4 in. top-seal adaptors.

Features

• Lever: Duratuff®
• Pins: stainless steel
• Gasket: Nitrile

Downloads

Product Literature (PDF Download)