You will find three types of UPVC Door Hinges. Butt type PVCU Door Hinges sometimes called a pencil or cylinder hinge, Flag type UPVC Door Hinges, and Rebate UPVC Hinges. These type of double glazing door hinges have been used by pvcu door suppliers since the late 1970's. Inevitably some suppliers are no longer trading and therefore have ceased manufactureing. However you should be able to identify a suitable replacement from another manufacturer. To help identify the door hinge you want to replace have a look at the diagram below, it should be clear what type of hinge you are after. Identifying a Butt, Rebate or Flag Hinge