SCH 20 SMLS Steel Pipe Dimensions and Thickness Chart

　　SCH 20 steel pipe is one of the lighter wall thickness schedules used in low-pressure piping systems. Although it is not as commonly referenced as Schedule 40 or Schedule 80, it still plays an important role in applications where flow capacity matters more than pressure resistance.

　　This guide breaks down SCH 20 steel pipe dimensions, wall thickness, and practical usage in a clear, engineering-based way—without unnecessary complexity.

　　What is SCH 20 Steel Pipe?

　　Schedule 20 (SCH 20) refers to the wall thickness classification of a steel pipe under ASME B36.10 and B36.19 standards.

　　In simple terms:

　　The higher the schedule number ， the thicker the wall

　　SCH 20 ：relatively thin wall pipe

　　Designed for low-pressure and non-critical systems

　　SCH 20 Steel Pipe Dimensions Overview

　　Unlike pressure rating, SCH 20 dimensions depend mainly on outside diameter (OD) and wall thickness.Below is a standard reference chart used in industry practice.

　　The inner diameter (ID) is approximate and can vary slightly based on manufacturing tolerances.

　　Larger pipe sizes for SCH 20 are available upon request.

　　Dimensions are based on ANSI/ASME standards for steel pipes.

　　NPS (Nominal Diameter) ≠ Actual Inner Diameter

　　This is a common misconception. For example, a pipe with NPS 12" has an actual outer diameter of 323.8 mm (approximately 12.75 inches), not 12 inches.

　　The golden rule: When NPS ≤ 12 inches, NPS corresponds neither to the outer nor the inner diameter; it's merely a designation. Only when NPS ≥ 14 inches does the NPS value essentially equal the actual outer diameter (in inches) of the pipe.

　　Schedule 20 Pipes Wall Thickness

　　Wall thickness values are based on ASME B36.10M standards.

　　For larger sizes or additional wall thickness options, custom solutions may be available.

　　The above data applies to steel pipes commonly used in low-pressure applications.

　　Common Applications of SCH 20 Steel Pipe,HVAC chilled water systems,Fire sprinkler auxiliary lines (low-pressure sections),Agricultural irrigation,Light industrial fluid transfer,Structural tubing in non-load critical areas.

　　SCH 20 steel pipe is a lightweight, cost-efficient piping option designed for low-pressure systems where flow efficiency matters more than strength. While not suitable for heavy-duty industrial pressure applications, it remains a practical choice in HVAC, drainage, and light fluid transport systems Email : pipe@stpipefitting.cn.