How are these hinges attached into the metal door frame?

Question

Bought our apartment in the Netherlands recently, and we're trying to replace the beat up, landlord grade, hollow core doors, with something a bit nicer. The issue I'm having is that I've no idea what is likely to be going on inside the doorframe to attach the hinges. They have these little metal washers that are working as a frame attachment, but would like to know if anyone knows what these fittings for a metal frame are called, or how they work?

I assume they're similar to a drywall anchor on the inside, but I don't want to break one if it turns out they're welded on. A link to what the hinges look like off the door

Answer 1

After a whole bunch of research, and some removal of doors I have an answer to my question

The doorframes are a Berkvens Berdo door mounting system. The white washers are integral to the doorframe, welded in place as part of the system. Apparently super common in the netherlands.

The particular type of doorframe basically has an internal clamp system, which it turns out made my next project much easier - in order to reverse the opening direction of one of the doors, you undo all the bolts in the doorframe, trim off any silicon or other sealant, and the doorframe comes off in pieces, like a kind of heavyweight ikea structure.

You then turn the pieces round, check they're level, and rescrew and reattach the doorframe. It was about an afternoons work for my slow, not exceptionally handy self, and just needed something to unscrew the door with, and a little resealing and repainting where I scuffed the wall a bit. All in all, pretty painless

Link to their instructions if anyone else ends up struggling https://berkvens.nl/model/berdo

Answer 2

The white washers you refer to are the flanged part of the hinge anchors you see outside of the frame. To support the weight of the door they are most likely welded or press-fitted to the inside of the frame, and are tube like within the metal door frame. One being smooth for the indexing dowel. The other threaded for anchoring the frame part of the hinge.

You unscrew the frame part by using a tool through the hole aligned with the threaded top anchor screw. (The type of tool, slot, Philips, Allen needs to be determined by looking in that hole.) The anchors in the frame will remain intact. Removing them may be difficult.

Your intention is to replace the door. Perhaps you need only to find a suitable door that can accept the same hinges. Remove the part from the old door and reuse it. Then there is no issue with the frame side.