What is the typical manufacturing method for ductile iron pipe?

• A. Centrifugal casting
• B. Die casting
• C. Extrusion
• D. Forging

Answer: (A)

Ductile iron pipe is typically made by centrifugal casting, where molten iron is poured into a rapidly rotating mold to form a hollow cylinder. The spinning motion creates centrifugal force that pushes the metal to the mold walls, producing a pipe with uniform wall thickness and dense, sound structure. This method is well-suited for large, long sections and helps minimize porosity and other defects, while also supporting efficient, continuous production. The other methods don’t fit this purpose: die casting is designed for small parts and non-ferrous alloys, extrusion is better for continuous solid or hollow profiles in materials that can be pushed through a die, and forging is for shaping solid pieces and isn’t practical for long, hollow pipes.