Schedule 40 pipe refers to a standard thickness (wall thickness) for pipes, mainly used in industries like construction, plumbing, and manufacturing.
Here’s a clear breakdown:
What is Schedule 40 Pipe?
"Schedule" refers to the wall thickness of the pipe.
"40" is a number that represents a specific wall thickness based on the pipe's nominal size (outer diameter).
Material: Schedule 40 can apply to many materials — carbon steel, stainless steel, PVC, CPVC, etc.
Common Standard:
For steel pipes, Schedule 40 is typically based on ASTM standards (like ASTM A53, ASTM A106 for carbon steel pipes).
Key Features:
| Feature | Description | 
| Wall thickness | Medium wall thickness — a balance between strength and weight | 
| Pressure rating | Good for moderate pressure applications (varies by material and size) | 
| Material availability | Steel, stainless steel, PVC, CPVC, and more | 
| Common use | Plumbing, water lines, gas lines, fire sprinkler systems, structural support | 
Example (for Carbon Steel Pipe):
| Nominal Pipe Size (NPS) | Outer Diameter (OD) | Wall Thickness (Schedule 40) | 
| 1 inch | 1.315 inches (33.4 mm) | 0.133 inches (3.38 mm) | 
| 2 inches | 2.375 inches (60.3 mm) | 0.154 inches (3.91 mm) | 
| 4 inches | 4.5 inches (114.3 mm) | 0.237 inches (6.02 mm) | 
Note: As the pipe size increases, the wall thickness for Schedule 40 also increases.
Schedule 40 vs Other Schedules:
| Schedule | Wall Thickness | Typical Use | 
| 10 | Thin wall | Low pressure, lightweight piping | 
| 40 | Medium wall | Standard piping for water, air, gas | 
| 80 | Thick wall | Higher pressure and strength needs | 
| 160 | Very thick wall | Very high-pressure systems | 
Quick Summary:
Schedule 40 = standard wall thickness.
Used for moderate pressure and strength needs.
Available in many materials like steel, stainless steel, PVC.
Most common choice for residential, commercial, and industrial piping.