glazing in fire doors

[alfi]

I was wondering if anyone could offer some advice please. A recent fire risk assessment in a residential block of two storey apartments, with the corridors divided by double swing FD30 doors, consisting of mainly small glass panels 15 in total. As the doors are probably about 30 years old, i'm concerned that the glass and beading may not resist the heat from a fire and could fail. My questions is, "for small panels in fire doors whats is the minimum thickness required", there are not markings on the glass but from experience it fells like 4mm , certainly not 6mm and I can't tell if its toughened or plate.

any advice would be apreciated or indication on guidance for older fire doors

[kurnal]

It sounds as though they never have been FD30 doors.
Doors installed to simply subdivide corridors and separate the storey exits only need to be FD20 as they are unlikely to be directly exposed to radiated heat- their role is really more to prevent the spread of smoke. However to my recollection 6mm polished plate glass was acceptable to a total area of 40 sq inches. Other than that its georgian wired or fire rated toughened glass. In all honesty though if its multi pane the timber will probably be the weakest link - what are the dimensions of the stiles, rails and beadings? And what type of wood?