Which statement describes the difference between Schedule 80 and Schedule 40 pipes for the same NPS?

• A. They have the same wall thickness
• B. Schedule 80 is lighter than Schedule 40
• C. Schedule 80 has better corrosion resistance
• D. Schedule 80 has thicker wall and higher pressure rating

Answer: (D)

Pipe schedules indicate wall thickness for a given nominal pipe size. For the same NPS, a higher schedule number means a thicker wall. Schedule 80 has a thicker wall than Schedule 40, so it can withstand higher internal pressures (higher pressure rating). The thicker wall also makes the pipe heavier and slightly reduces the internal diameter, which can affect flow. Corrosion resistance isn’t determined by the schedule; it depends on the material and coatings. So the statement that best describes the difference is that Schedule 80 has a thicker wall and a higher pressure rating.