The lid has a reinforment in the inside. There are some bend pieces
of thin steel rod/wire welded to the inside of the lid. These wires
ar to prevent the linning of the lid falling out due to the heating
and cooling movements of the steel.
On the side of the hinge and the grip there is some steelbar reinforments.
this is to spread the forces near the hinge over the sides and top
of the lid. The steel sides are to thin to take the forces alone and
the lining is to crumbly and fragile to contribute to the stability
of the lid.