3381 - B-Size Acetylene Hose Nut | 9/16"-18 LH Brass Fitting

Fix Your Hoses with the Right Hardware

Don't let a stripped nut or a damaged hose end put your welding project on hold. The ESAB 3381 B-Size Acetylene Hose Nut is the essential replacement part you need in your toolbox. We've all been there—you're setting up your torch, and the threads on your old hose nut are just too worn to bite, or maybe the hex is rounded off from years of use. This replacement nut allows you to salvage your expensive welding hose by simply cutting off the bad end and installing a new fitting assembly. It's a quick, cost-effective solution that keeps you burning without buying a whole new twin-line hose.

This nut is designed specifically for the "Fuel" side of your oxy-fuel setup. That means it has the signature Left-Hand threads (turn left to tighten, right to loosen). You can easily identify it by the groove or notch cut into the middle of the hex—that's the universal sign for "Fuel Gas" (Acetylene, Propane, Chemtane, etc.). It fits standard B-size connections, which are the most common fittings found on regulators and torches for 1/4-inch and 3/16-inch hoses. Made from solid brass, it resists rust and stands up to the daily grind of the shop.

Safety First: Why the Left-Hand Thread?

You might wonder why fuel nuts turn the "wrong" way. It's a fail-safe design to make sure you never accidentally plug your acetylene hose into your oxygen regulator. Oxygen and grease or fuel don't mix—in fact, they can be explosive. By making the threads incompatible, the industry keeps you safe. When you are repairing your hose, always double-check that you are putting this notched nut on the Red (or Orange) hose. Pairing this nut with a quality hose nipple and a proper crimp (or hose clamp for low-pressure temporary fixes) ensures you get maximum flow and zero leaks.

Whether you are a professional fabricator building custom-length hoses for a long-reach job or a hobbyist fixing up an old torch kit, having a few of these ESAB 3381 nuts on hand is a smart move. They are cheap insurance against downtime. Remember to always leak-test your new connections with soapy water before lighting the torch. A bubble-free connection means you are good to go.