A special German standard for square covers (sewage and the like) on roads that defines the requirements for covers in the C250 (
) D400 (
) load class. This standard defines the size, the materials and the weight in which the lid should withstand in order to the load.
The standard title is: Gully tops 500 × 500 for road gullies, class C 250 and class D 400
Download document from Beuth Verlag (payment) https://www.beuth.de/de/norm/din-19583-1/154438471