Ductile iron pipes manufactured according to different standard based on different project demand.
In order to distinguish different standard pipes, one method is to print standard on the surface of pipes, the other is at the socket end of pipes painted with red color.
so it is very clear can see which standard it is.
EN545 is ductile iron pipes for drink water supply, end of socket pipes is black;
EN598 is ductile iron pipes for waste water drainage, end of socket pipes is red.