Stainless Steel Tubing vs Pipe: Key Differences You Need to Know

The terms “stainless steel tubing” and “stainless steel pipe” are often used interchangeably, but they refer to fundamentally different products with different sizing systems, manufacturing standards, and applications. Understanding the difference prevents ordering mistakes and ensures you get the right product for your project.

1. Sizing System: The Fundamental Difference

The most important distinction lies in how each product is sized:

• Pipe is specified by nominal pipe size (NPS) — the outside diameter is fixed for each NPS, and wall thickness varies by schedule (SCH 5, 10, 40, 80, 160). For example, 2″ pipe always has an OD of 60.3mm regardless of wall thickness.
• Tubing is specified by actual outside diameter (OD) and actual wall thickness (WT), both measured in millimeters or inches. A 25mm tube has an actual OD of 25mm.

2. Manufacturing Standards

Stainless steel pipes and tubes follow different international standards:

• Standards for Pipe: ASTM A312 (seamless & welded), ASTM A358 (factory-welded), ASTM A790 (duplex). Dimensional standards: ASME B36.19.
• Standards for Tubing: ASTM A269 (general service), ASTM A213 (boiler/superheater), ASTM A249 (welded). Dimensional standards: ASTM A269 tables.

3. Tolerance Differences

Tubing generally has tighter tolerances than pipe:

• Tubing OD tolerance: ±0.5% or ±0.05mm (whichever is greater)
• Pipe OD tolerance: ±1% for sizes above NPS 4
• Wall thickness: Tube wall thickness is controlled more precisely, typically ±10% vs ±12.5% for pipe

4. Applications

• Pipe applications: Process piping in oil & gas, chemical plants, water distribution, steam systems. Designed to carry fluids under pressure.
• Tubing applications: Heat exchangers, instrument lines, sanitary systems, hydraulic lines, architectural handrails, medical devices. Used where precise dimensions matter.

5. Surface Finish & Cleanliness

Tubing often requires superior surface finishes:

• Sanitary tubing (ASTM A270) requires internal Ra ≤ 0.8μm
• Annealed & pickled finish is standard for most tubing
• Bright annealed (BA) finish is available for tubing when polish is needed
• Pipe typically uses standard mill finish (1D or 2D)

6. Pricing Comparison

Stainless steel tubing is typically 20–40% more expensive than pipe of similar material because of tighter tolerances, additional quality controls, and smaller production volumes. Always specify correctly to avoid overpaying for tube when pipe would suffice, or vice versa.

Summary Table

Conclusion

Knowing the difference between stainless steel tubing and pipe helps you order correctly, avoid costly mistakes, and optimize your project budget. CoreMetal Steel supplies both stainless steel pipe (ASTM A312) and precision tubing (ASTM A269/A213) in all major grades. Contact us for competitive pricing.