National Mfg N147-827 4x4 Plain Steel Loose Pin Hinge

Product Description

The NATIONAL MFG/SPECTRUM BRANDS HHI N147-827 is a 4-inch by 4-inch plain steel full mortise surface hinge designed for heavy-duty door installations. Built from cold rolled steel, this non-swaged hinge is intended for surface application by welding, making it suitable for industrial and commercial door assemblies where a secure, flush-mounted connection is required. The 5-knuckle construction provides stable pivot support, and the loose pin design allows door removal without unbolting the hinge leaves from the frame or door. Licensed tradespeople and millwork contractors working in commercial construction or industrial facilities will find this hinge well-suited for high-cycle door applications.

This hinge is appropriate for surface-mount door installations where welding is the preferred or specified attachment method. The full mortise design seats flush with the door edge and frame for a clean, professional finish. It ships boxed loose, making it compatible with both single-unit replacements and larger project quantities. Typical applications include metal door frames, hollow metal doors, and industrial enclosures where conventional screw-mount hinges are not adequate.

Key Features

• 4 inches x 4 inches hinge leaf size for substantial door support
• Cold rolled steel construction for durability in demanding environments
• Non-swaged design engineered for surface application by welding
• 5-knuckle configuration provides smooth, stable pivot action
• Loose pin allows door removal without disturbing hinge mounting
• Full mortise design for flush, professional installation

Compatibility

Designed as an OEM-style replacement or new-installation surface hinge for metal doors and frames requiring a welded, full mortise 4-inch by 4-inch plain steel hinge.

Installation Notes

Installation is typically performed by a qualified millwork, ironwork, or door hardware professional. Welding should follow applicable structural and fire-rated door assembly codes, and all welding operations must be performed with appropriate personal protective equipment and ventilation. Ensure the door is properly supported and the frame is plumb and square before tacking the hinge in place. Do not substitute mechanical fasteners for the specified welded attachment on fire-rated or high-cycle assemblies.