BB31 4-1/2 x 4-1/2 BALL BEARING .134 HINGE
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BB31 4-1/2 x 4-1/2-Inch Standard-Weight Ball-Bearing Hinge
Our BB31 full-mortise hinge combines a 4-1/2 x 4-1/2-inch size, .134-inch leaf thickness, and two ball bearings in a standard-weight architectural hinge. It is a practical choice to evaluate for medium-frequency commercial doors when the actual door duty, preparation, environment, and hardware specification call for this hinge type.
Documented Specifications
- Model: BB31.
- Size: 4-1/2 x 4-1/2 inches.
- Thickness: .134 inch.
- Mounting: Full mortise, template type.
- Weight class: Standard weight.
- Bearing arrangement: Two ball bearings.
- Corners: Square-corner model.
- Family material choices: Steel, stainless steel, and brass, according to the actual specified construction.
Full-mortise preparation recesses the leaves into the door edge and frame. Match the leaf dimensions, mortise depth, screw pattern, and reinforcement to the actual opening. A matching nominal size does not by itself establish replacement compatibility.
Current Finish Selections
Offered finishes include US26D Satin Chrome, US32D Satin Stainless Steel, US15 Satin Nickel, US15A Satin Nickel Blackened, US26 Bright Chrome, US1 Matte Black, US10B Antique Bronze Oiled, US10 Satin Bronze, US10A, US3 Bright Brass, US4 Satin Brass, US5 Antique Brass, and USP Primed Gray. Select the actual offered variant and verify the specified material where environmental exposure matters. A decorative finish name does not establish the base metal of every hinge.
Practical Uses
- Medium-frequency commercial openings: Evaluate BB31 for offices, consultation rooms, storage rooms, and similar applications where standard-weight ball-bearing hinges meet the actual door requirements.
- Compatible replacement work: Match an existing 4-1/2 x 4-1/2-inch, .134-inch full-mortise preparation after checking the exact hole pattern.
- Coordinated hardware packages: Select the finish and construction appropriate to the door, frame, closer, and environment.
Everyday example: A maintenance technician replacing worn hinges on an office door measures the existing leaf size and thickness, checks reinforcement and screw engagement, and compares the BB31 preparation reference with the opening. After installing aligned hinges, they test the door, closer, latch, and frame clearances together rather than assuming that new bearings alone will correct a sagging or damaged frame.
Selection and Installation Checks
- Confirm the door duty: Review door weight, width, height, use frequency, closer forces, and the required hinge quantity and spacing.
- Match the preparation: Check mortise size and depth, corner geometry, screw positions, and door/frame reinforcement.
- Choose suitable construction: Coordinate the actual material and finish with the installation environment.
- Use appropriate fasteners: Our commercial catalog references #12-24 x 1/2-inch machine screws and #12 x 1-1/4-inch wood screws for this standard-weight group. Follow the supplied hardware and approved substrate preparation.
- Keep hinge axes aligned: Seat leaves correctly without forcing misaligned screws or distorting the hinge.
- Test the complete opening: Check swing, gaps, latch engagement, closer operation, and any required clearances.
Pin Security and Rated Openings
NRP means non-removable pin, a pin-security feature to coordinate where the hinge pin could be exposed on an outswing door. Do not assume it is included in an unmarked BB31 variant; verify the exact specified order.
Our commercial catalog identifies UL-listed steel and stainless-steel BB31 hinges for use on swinging fire doors, with a 3-hour listing reference. That hardware reference does not establish a rating for every material, selection, or complete opening. Confirm the exact listed hinge, fasteners, preparation, and approved door-and-frame assembly. Do not transfer the steel/stainless listing to a brass construction.
Problems It Helps Address
- A project specifies standard-weight ball-bearing hardware: Provides the documented BB31 dimensions and two-bearing arrangement.
- A replacement must match existing mortises: Identifies the size, thickness, and exact preparation reference to check.
- A coordinated architectural finish is needed: Offers the listed finish selections without assuming all have the same base material.
Care and Matching Reference
Periodically inspect screw tightness, hinge alignment, bearing movement, finish condition, and door gaps. Correct damaged preparation, loose reinforcement, or door sag rather than forcing operation. Follow the supplied maintenance guidance and use finish-appropriate cleaning methods.
