Dear hadi,
I tried googling "baking steel conveyors".
The only descriptions i saw were high quality steel (whatever that means!) and stainless steel 304 as mentioned several times previously.
I am no baking expert but I doubt very much (??) that any reputable manufacturer will recommend materials like mild steel for direct food contact at presumably high temperature conditions although i hv certainly seen it used in some bread pre-baking operations for (presumably) economic reasons.The long term surface durability compared to other stainless steel units in parallel use was sadly only too visible and generated a negative comment after my audit (the output showed no visible/significant magnetically detectable contamination etc). I daresay a more specialised (competent?

) auditor might hv been even more severe (the equipment was 2nd hand and 20years old although did possess an original manufacturer's specification denoting food grade

?.)
My conclusion is that if a reliable manufacturer will not give you a food grade certification for a
recently purchased new unit, it very likely isn't.

Sorry.
The only solution may unfortunately be the obvious one.
Rgds / Charles.C
PS @AS NUR thks for the nice attachment