Does the outer diameter of a pipe remain the same regardless of its schedule?

Study for the Gas Metal Arc Welding Exam, including GMAW, FCAW, and MCAW methods. Use flashcards and multiple choice questions with hints and explanations for effective learning. Get ready for your welding certification!

The outside diameter is set by the nominal pipe size and stays the same across different schedules. Schedule refers to wall thickness, not the pipe’s width, so increasing the schedule makes the walls thicker while the outside dimension remains essentially constant. For example, a 2-inch nominal pipe has the same outside diameter across schedules (about 2.375 inches); moving to a thicker-walled schedule reduces the inner diameter but leaves the outer diameter unchanged. You can see this by the simple relation for inner diameter: ID = OD minus twice the wall thickness. This consistency in outer diameter is why fittings and flanges are sized by the nominal size, while the schedule controls how much material sits on the walls.