PVC fittings can be used with other pipe types when they share the same outside diameter; which material is commonly paired with PVC for fittings?

• A. Copper pipe
• B. PVC pipe
• C. Ductile-iron pipe
• D. Stainless steel pipe

Answer: (C)

The key idea is that fittings can connect different pipe materials as long as their outside diameters match, so you can use a fitting designed for one material with another if the sizing aligns. Ductile iron pipe uses standard IPS outside diameters that line up with many PVC sizes, and there are abundant transition and adapter fittings to join PVC to DIP. This makes ductile iron a common partner for PVC fittings in water systems, especially when tying new PVC sections into existing DIP mains. Other materials exist for some service connections, but they’re not as universally matched with PVC by the standard sizes and available fittings.