In a gas piping system, the minimum inside bend radius for metallic pipe should be at least how many times the outside diameter of the pipe?

• A. 6 times
• B. 4 times
• C. 1.5 times
• D. 2 times

Answer: (A)

In gas piping, the bend radius is a safety factor that prevents the bend from being too sharp, which can stress the pipe and weaken the wall where it curves. The minimum inside bend radius for metallic pipe is six times the pipe’s outside diameter. This larger radius helps maintain the pipe wall thickness through the bend, reduces stress concentrations and the potential for cracks or leaks, and preserves smoother flow with less pressure loss. Smaller radii—like two or four times the diameter or even 1.5 times—increase bending stress and wall thinning, making leaks or failure more likely. Six times the outside diameter is the standard that provides the needed margin for safe, durable gas piping.