What standard is used for threaded connections into a gasoline fuel tank?

The American Standard Taper Pipe Thread (NPTF) is the correct standard used for threaded connections into a gasoline fuel tank primarily due to its design features that enhance leak prevention and compatibility with liquid fuels.

NPTF threads provide a tighter, more reliable seal compared to other thread types. This is crucial in fuel systems, as even minor leaks can lead to safety hazards, including fire risks and fuel contamination. The NPTF standard includes a specific profile that allows for mechanical interaction and sealing when connections are made, effectively minimizing the risk of leaks.

In contrast, options like the National Pipe Thread (NPT) do not provide the same level of sealing capability and may not be as effective for fuel applications. The Metric Thread Standard (MTS) and Universal Thread Standard (UTS) are generally not used for fuel applications, especially within North American contexts, making NPTF the most suitable choice in compliance with ABYC standards for safe marine operations involving gasoline fuel tanks.