Definition

• "Schedule" refers to the wall thickness of pipes with the same outside diameter. It is standard industry terminology adopted by the American National Standards Institute.
  
  

Schedule List

• For a relatively constant pipe outside diameter, the wall thickness varies from Schedule 10 (light) to Schedule 40 (standard weight) to Schedule 80 (extra strong) to Schedule 160 (double extra strong).
  
  

Schedule 40 Example

• A Schedule 40 steel pipe, with an outside diameter of 1.050 inches, has a wall thickness of 0.113 inches and an inside diameter of 0.824 inches.
  
  

Schedule 80 Example

• A Schedule 80 steel pipe, with an outside diameter of 1.050 inches, has a wall thickness of 0.154 inches and an inside diameter of 0.742 inches.
  
  

Significance

• Schedule 40 pipe is typically used in construction. However, if a stronger pipe is needed, then Schedule 80 can be used. An example where Schedule 80 should be considered is if the pipe is exposed during construction. The stronger pipe is more resistant to incidental bumping by workers or equipment.