The high amount of Phosphorus (P₄) causes lime to become embrittled, thus reducing the toughness and increasing the possibility of breakage during processing, it also causes intergranular segregation during continuous casting and deteriorates the ductility and toughness of products such as high strength plates and pipes, cryogenic steels, pressure vessel plates, etc.

Thus the ideal quantity of it to be found in limestone should be less than 0.1%, which does not exceed above 0.05% in our product.