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--Mastering Schedule 40 vs Schedule 80 for Precise Piping Selection
Explore Schedule 40 vs 80 stainless steel pipe dimensions.
Master ASME B36.19M sizing, wall thickness, and pressure ratings for compliant piping design.
Accurately understanding the sizing system and wall thickness grades (Schedule) of stainless steel pipes is a prerequisite for ensuring pressure resistance, flow rate matching, and compliant design. This article focuses on the commonly used Schedule 40 and Schedule 80 to help quickly establish selection logic.
Core Parameters of Stainless Steel Pipe Dimensions
NPS (Nominal Pipe Size): Nominal diameter in imperial units, such as NPS 2".
OD (Outside Diameter): A fixed value, for example, NPS 2" corresponds to an OD of 60.3mm.
Schedule Wall Thickness Grade: Determines the actual wall thickness and pressure resistance, such as Sch 40 and Sch 80.
Key Standards: Dimensions and wall thickness are usually based on ASME B36.19M; materials and manufacturing often refer to ASTM A312.
Schedule 40 vs Schedule 80
Schedule 80 is higher and suitable for high-pressure systems.
Schedule 80 is heavier, increasing material costs and installation load.
Increased wall thickness reduces the inner diameter, affecting flow rate and pressure drop. Schedule 40 vs Schedule 80 Size Comparison Chart
The following are common size illustrations (unit: mm):
NPS | Outer Diameter OD | Sch 40 Wall Thickness | Sch 80 Wall Thickness | Sch 40 Inner Diameter | Sch 80 Inner Diameter |
1" | 33.4 | 3.38 | 4.55 | 26.64 | 24.3 |
2" | 60.3 | 3.91 | 5.54 | 52.48 | 49.22 |
3" | 88.9 | 5.49 | 7.62 | 77.92 | 73.66 |
4" | 114.3 | 6.02 | 8.56 | 102.26 | 97.18 |
Calculation Formula: Inner Diameter = Outer Diameter − 2 × Wall Thickness
Selection Recommendations: Design Pressure and Temperature (based on ASME design formulas) Corrosion Allowance Service Life Requirements Material Grade (304/316L/2205/2507/625, etc.) For corrosive or high-temperature conditions, simply increasing the wall thickness cannot replace material upgrades.
MTSCO supplies seamless and welded stainless steel pipes in various specifications according to ASME B36.19M, ASTM A312, and other standards, covering austenitic, duplex, and nickel alloy materials. Through ISO/PED system management, PMI re-inspection of raw materials, and full-process traceability quality control, we help customers achieve stable supply and project-level compliant delivery under different schedule requirements.