WINTOWIN 2" NPT Flip-Top Vented Locking Fill Cap — 2-Inch Cast Iron, Powder-Coated Secure Closure

WINTOWIN’s 2-inch flip-top vented locking fill cap is a cast-iron replacement cap that seals 2" NPT fuel ports while allowing controlled venting and the option to lock the cap for secure diesel transfer storage.

Designed for diesel transfer tanks, fuel transfer containers and outdoor storage tanks, this flip-top fill cap swaps in for worn bung plugs and provides a sturdier, more secure closure. Finished with a powder coat to resist rust, it combines a hand-tight thread fit, integrated venting and a lock port so you can keep contents secure and contamination out without special tools.

How does this cap prevent leaks and contamination?

The cap uses a robust threaded 2" NPT fit plus an internal dustproof seal to block dirt and water. When closed, the seal compresses to reduce seepage; the flip-top retention minimizes accidental opening during handling.

• Precision cast iron body with powder coat finish for corrosion resistance
• Tight rubber or elastomer seal to block dust and moisture
• Threaded 2" NPT design for a secure, leak-resistant engagement
• Flip-top closure reduces accidental spillage during transport

Will this fit my diesel transfer tank or fuel transfer container?

This cap is engineered for standard 2" NPT threaded ports commonly found on transfer tanks and outdoor storage drums. It replaces most worn or missing bung-style caps without adapters when your container uses a 2" NPT thread.

• Direct replacement for standard 2" NPT threaded openings
• Suits diesel transfer tanks, portable fuel tanks and outdoor oil drums
• No adapters required for true 2" NPT ports—check thread match before purchase
• Hand-tight installation supports quick swaps in the field

How easy is installation and locking?

Installation takes three simple, tool-free steps: thread the cap into the port, hand-tighten until seated, and close the flip top. The integrated lock port accepts a small padlock to prevent unauthorized opening, useful for shared worksites or outdoor storage.

• Thread in by hand—no tools required
• Quick flip-top operation for fast access to the fill port
• Lock port designed for standard small padlocks for added security
• Built-in venting maintains pressure balance while closed

What materials and durability features should I expect?

The cap is made from precision-cast iron and protected with a durable powder coat to resist chipping and corrosion in outdoor environments. The internal vent system and sealing surfaces are engineered for repeated use without rapid wear.

• Cast iron construction for strength and longevity
• Protective powder-coat finish to reduce rust on exposed surfaces
• Vented design helps equalize tank pressure during filling and storage
• Seals and moving parts sized for frequent opening and closing

Who is this for? WINTOWIN’s 2" flip-top vented locking fill cap is aimed at contractors, fleet managers, farmers, and DIYers who need a rugged, lockable replacement cap for diesel transfer tanks and portable fuel containers. If you use standard 2" NPT fuel ports and want a low-maintenance, secure cap that resists corrosion and contamination while allowing controlled venting, this cap is built to fit those needs.