marking steel plates

[Alecs76]

egregi
I would like to refer the following question:
steel plates, simple carpentry to understand, to be used as cover of pits to which rules do they refer?
I do not think they have structural employment, so they should not fall within the scope of 1090.

thanks for suggestions

 

[SHIREN]

[MENTION=20232]alecs76[/MENTION]a cover of pits
I think it should be done with crown closure systems
more simply locks that go according to norm
uni en 124
in various resistance classes
b 125 kn
c 250 kn
d 400 kn
and 600 kn
f 900 kn
Thank you very much