Barrel hinge

A barrel hinge is a type of hinge made of two parts that sit one on top of the other on a pin: one is fixed to the frame and the other to the leaf. It is the hinge fitted on almost all security doors, because it carries a lot of weight.

You can recognise it because it is a thick cylinder with no visible leaves. With the door open, the leaf lifts upwards off the pin, and that is why security doors also have hinge bolts on that edge. Many barrel hinges are adjustable, so the leaf can be raised, lowered or brought closer to the frame without taking anything apart.

With use and weight, barrel hinges give way and the door drops a little. You notice it because the key is hard to turn or you have to push the door for it to engage. A good adjustment in time avoids straining the lock. It is part of what we do with security doors.