Answer
Jul 11, 2025 - 01:09 PM
Both Schedule 40 and SDR 35 pipes typically have a nominal 4-inch diameter, but their outer diameters differ slightly. Schedule 40 has an OD of approximately 4.5 inches, while SDR 35 has an OD of about 4.215 inches. The inner diameter of SDR 35 is slightly larger (around 3.975 inches) compared to Schedule 40 (around 3.998 inches) due to SDR 35's thinner walls.
