Some varieties can bear door weights of as much as 20,000 lbs. Such hinges can weigh as much as 55 lbs and are often affixed to doors by welding instead of with fasteners. The United States Army makes use of such hinges in explosion-proof bunker doors. They are usually made of steel and can be costly because they are often specially designed for unique uses; 20,000 lbs doors are not common even in industrial contexts.
Heavy duty hinges can be constructed in many different configurations with many different materials and to a range of specifications. The more demanding the application, the more likely the hinge will be made of steel or stainless steel, both of which are valued for their strength. A hinge’s durability and load-bearing capacity depends on composition and configuration.
One of the simplest and most reliable hinge configurations is the butt hinge. Many butt hinges are nothing more than two metal plates joined by a pin. Both plates are machined on one side so that they interlock with each other. Those interlocking members are then bent to form a closed circle, and the pin is placed in the circle, which joins the plates together.
Butt hinges are valued for their simplicity and functionality. In addition to butt hinges, several other varieties of heavy duty hinges are available. The continuous hinge, also called a piano hinge, is cut to support the entire length of a door. They support heavy doors evenly because every knuckle is a load-bearing point. Strap hinges are made of heavy-gauge metal, usually stainless steel, and mounted on the front of a heavy door. Slip-joint hinges are another type of hinges that are used for quick and easy door removal. Slip-joint hinges consist of a male leaf with a pin and a female leaf with no pin.