Ductile iron pipes vs. mild steel pipes as pressurized pipelines

For water main pipe size less than 600mm, ductile iron is generally used since internal welding for steel pipes below 600mm is problematic to be carried out. Furthermore it needs only simple jointing details that allows for a faster rate of construction. For water main pipe size above 600mm, steel pipes are suggestedsince steel pipes are lighter than ductile iron pipes for the same material strength and consequently the cost of steel pipes is usually less than that of ductile iron pipes. Additionally, in areas of difficult access the use of lighter mild steel pipes has a benefit over ductile iron pipes for easy handling.