High-Level Summary
DIN 17100 was a fundamental German standard for the quality and delivery conditions of carbon steel grades for general structural purposes. When we talk about a "DIN 17100 Carbon Steel Pipe," it means a pipe manufactured from a steel grade defined by this standard.
Crucially, DIN 17100 has been officially replaced by the European standard EN 10025. However, the old designations are still widely used in industry, so understanding them is essential.
1. What was DIN 17100?
Title: DIN 17100: Stähle für allgemeine Bauteile; Gütebedingungen (Steels for general structural purposes; Quality conditions)
Scope: It specified the requirements for unalloyed, quality carbon steels primarily used in construction, machinery, and vehicle manufacturing. It covered various product forms, including plates, sections, bars, and-importantly for your question-tubes and pipes.
Key Parameters: The standard defined chemical composition, mechanical properties (tensile strength, yield strength, impact energy), and delivery conditions.
2. Understanding the Steel Grade Designations
The most common carbon steel grades from DIN 17100 follow a specific naming pattern: St XX YY
St: Stands for Stahl (Steel).
XX: A two-digit number indicating the minimum yield strength (Streckgrenze) in kgf/mm². To get the approximate value in MPa (N/mm²), multiply by 10.
YY: A letter(s) indicating the material quality, specifically the impact energy (toughness) requirement.
U: Unberuhigt (Rimmed steel) - Basic quality, lowest toughness.
R: Beruhigt (Killed steel) - Better quality, good toughness.
RR: Beruhigt mit besonderem Güteanspruch (Special killed steel) - Higher toughness.
S: Schweißgeeignet (Suitable for welding).
Common DIN 17100 Grades for Pipes:
| DIN 17100 Grade | Approx. Min. Yield Strength (ReH) | Quality / Toughness | Key Characteristics & Common Pipe Applications |
|---|---|---|---|
| St 37-2 | 235 MPa | Killed Steel, Good | The most common general-purpose structural carbon steel. Good weldability and formability. Used for general structural pipes, handrails, low-pressure fluid transport. |
| St 44-2 | 275 MPa | Killed Steel, Good | Higher strength than St37-2. Used for structural components requiring more strength, machinery frames. |
| St 52-3 | 355 MPa | Killed Steel, High | High-strength low-alloy steel. Excellent for heavily loaded structures, crane booms, and high-stress applications. Not to be confused with the pressure vessel steel P265GH (which is similar but has stricter controls). |
Note: The -2 and -3 suffixes indicate the specified impact energy test temperature (+20°C for -2 and -20°C for -3), with -3 being tougher.
3. The Modern Equivalent: EN 10025
DIN 17100 was withdrawn and superseded by the European standard EN 10025. If you are ordering or specifying material today, you should use the EN 10025 designations.
Here is the direct equivalence for the most common grades:
| Old DIN 17100 Grade | Current EN 10025-2 Grade | Key Properties (Min. Yield Strength) |
|---|---|---|
| St 37-2 | S235JR | 235 MPa |
| St 44-2 | S275JR | 275 MPa |
| St 52-3 | S355JR | 355 MPa |
Decoding EN 10025:
S: Structural Steel
235: Min. yield strength in MPa
J: Impact energy of 27 J at room temperature
R: Minimum impact energy value
4. Important Distinction: DIN 17100 vs. Pressure Pipe Standards
This is a critical point. DIN 17100 is for structural steels.
DIN 17100 Pipes: Used for mechanical and structural applications where the load is primarily structural (e.g., supporting weight, frames, scaffolding). They are not primarily designed for containing pressurized fluids.
Pressure Pipe Standards: Pipes designed to carry pressurized fluids (water, steam, gas, oil) must meet different, more stringent standards that account for internal pressure, temperature, and corrosion. Common European standards for pressure pipes include:
EN 10216: Seamless steel tubes for pressure purposes.
EN 10217: Welded steel tubes for pressure purposes.
DIN 1629: The old German standard for seamless precision steel tubes.
A common pressure vessel/piping steel like P235GH (EN 10216) is chemically similar to St37-2/S235JR but has stricter controls on composition and properties to ensure safety under pressure.
Key Takeaways
DIN 17100 is Obsolete: It has been replaced by EN 10025.
"DIN 17100 Pipe" means a Structural Pipe: It is made from a general-purpose carbon steel grade like St37-2, St44-2, or St52-3.
Know the Modern Names:
St 37-2 is now S235JR
St 52-3 is now S355JR
Don't Use for Pressure: Do not use a pipe marked only with a DIN 17100 grade for pressurized applications. You must use a pipe certified to a pressure standard like EN 10216 or EN 10217.
When sourcing or specifying, always confirm whether the material is supplied to the old DIN standard (which is still possible) or the current EN standard to ensure compatibility and compliance with your project requirements.
