b.) Ductile iron.
Ductile iron pipes are known for their high strength and durability, which makes them suitable for use in a wide range of applications, including water distribution, wastewater treatment, and industrial piping systems. They have the highest normal maximum working pressure (PN) of all the types of pipes listed, which is typically between PN 10 and PN 40, depending on the pipe size and thickness. Reinforced concrete pipes have a maximum working pressure of around PN 10 to PN 15, while polyvinyl chloride (PVC) pipes typically have a maximum working pressure of around PN 12 to PN 18. High-density polyethylene (HDPE) pipes have a maximum working pressure of around PN 10 to PN 16.