High Quality 4 Ball Bearing Fire Door Hinge with 3 Hour Fire Rating - Suitable for Wooden and Metal Doors

We're looking at a UL-listed butt hinge here, the ky85 model, hitting that ANSI BHMA A156.1 Grade 1 standard with a 3-hour fire rating—it's basically built for commercial application where code compliance isn't optional. Available in stainles steel 201, 304, or 316, the surface finish has no sand holes, which matters when you're installing it on a visible door and don't want to deal with rust spots later. Most buyers go with the 304 for good balance of cost and corrosion resistance, but the 316 is better than that for coastal environments or chemical exposure.

It works on both wooden and metal fire-rated doors, so you're not locked into one substrate. The 4 ball bearings give you that smooth, quiet operation without the annoying squeak you get from cheaper hinges after a few months. Not ideal for lightweight hollow-core interior doors, though—this is overkill for that, and the weight of the hinge itself can be a pain to align on thinner frames.

For insallation, it's a standard butt hinge layout with included screws, but teh fix pin design means you can't remove the pin for door removal without tools—that's actually a feature for fire-rated assemblies where you don't want tampering. The tolerance on the barrel is tighter than most residential hinges, which helps with alignment when you're hanging a heavy fire door, but it also means you'll want to pre-drill pilot holes for the screws. 4-inch to 5-inch sizes, various configurations like square or radius corners, though we usually stock the 4.5-inch square corner most of the time.

Packaging is one pair per white box or color box, depending on your preference. Lead time runs about 30-35 days or so, which is pretty standard for this grade of hardware since it's all UL-certified per batch. We usually have stock, but confirm lead time for large orders—MOQ is typically 100 pairs for custom finishes or if you need 316 material.

Also, the fire rating holds up to NFPA80 requrements, but you'll want to check that hinge width matches your door's fire label—some older doors have specific hinge size requirement that aren't always documented. One thing a buyer might not think to ask: the screws included are typically self-tapping for metal frames, but for wooden doors you'll want to swap in wood screws for better hold, and we don't always have those in the box.