Tolerance Class

In detail

Tolerance Class defines the allowable deviation from nominal dimensions (OD, wall thickness, length) in steel pipe manufacturing. Standard commercial pipes follow Class A (±0.4 mm OD, ±12.5% WT), while precision applications require Class B (±0.2 mm OD, ±10% WT) or Class C (±0.1 mm OD, ±7.5% WT). DIN 2391 and EN 10305 define tolerance classes T1 through T4 for precision tubes. Tighter tolerances increase cost but are essential for hydraulic cylinders, instrumentation, and high-pressure applications.

Where you'll meet this in procurement

You will meet Tolerance Class on size charts, mill quotes, and fitment checks. Cross-check Tolerance Class against OD, wall thickness or schedule, length, and end finish so the delivered pipe matches flanges, fittings, and pressure duty—not just a familiar nominal label.

Related terms

• OD (Outside Diameter)The measured external diameter of a pipe in millimeters or inches, critical for fitment.
• Wall Thickness (WT)The radial thickness of pipe material determining strength, weight, and pressure capacity.
• Cold-drawnSeamless pipe pulled through dies at room temperature for tight tolerances and smooth finish.

Related resources

• Pipe schedule chart
• Steel pipe weight calculator
• Request a quotation (RFQ)
• Back to full glossary