DIN 1629 ST37 ST52 seamless steel pipes

DIN 1629 seamless steel pipe is a classic German industrial standard that defines the technical delivery conditions for seamless circular tubes made of non-alloy and alloy steels with special quality requirements.

These pipes are widely used in chemical equipment, pressure piping systems, mechanical engineering, boilers, and steel structures that demand high strength, pressure resistance, and long-term reliability.

Although DIN 1629 has been officially replaced by EN 10216-1, it continues to be referenced in legacy projects, industrial retrofits, and equipment documentation, proving its enduring reputation for performance and dependability.

1. What Is DIN 1629?

Full Title: DIN 1629—Seamless Circular Tubes of Non-alloy and Alloy Steels with Special Quality Requirements–Technical Delivery Conditions

Status: Superseded by EN 10216-1, which introduces new grade designations (such as P235TR1, P355TR1) corresponding to DIN 1629 grades like St37.0, St44.0, and St52.0.

Manufacturing Process: Produced seamlessly through hot rolling or cold drawing, ensuring no welded joints.

Application Scope: Ideal for pressure-retaining components such as boilers, pressure piping systems, hydraulic cylinders, and mechanical parts.

Quality Level:“Special quality requirements”denote stricter controls on chemical composition, mechanical strength, and non-destructive testing.

2. Key Features of DIN 1629 Seamless Steel Pipe

Seamless Construction
Eliminates weld-related defects such as inclusions or lack of fusion, ensuring consistent pressure resistance and superior safety.

Broad Material Range
Covers carbon and low-alloy steels, designed for balanced strength, ductility, and weldability.

Rigorous Quality Control
Each DIN 1629 seamless pipe undergoes hydrostatic testing, eddy current inspection, and tensile/impact testing to guarantee material integrity.

Excellent Machinability
Easily bent, welded, or machined, making it suitable for custom industrial fabrication and structural applications.

3. Material Grades and Mechanical Properties of DIN 1629 Seamless Pipes

Equivalent Grades

Tip: The St52.0 pipe is the most common choice for high-pressure systems, often supplied by St52.0 seamless pipe manufacturers and suppliers worldwide.

4. Chemical Composition (Typical Max Values) of DIN 1629 Seamless Pipes

This optimized chemical balance gives DIN 1629 seamless pipes exceptional strength, ductility, and impact resistance for high-stress environments.

5. Dimensions and Tolerances of DIN 1629 Seamless Pipes

Dimensional reference: DIN 2448–Seamless Steel Pipes, Dimensions, and Mass per Unit Length

Pipes are designated as outer diameter×wall thickness (e.g., 114.3×6.3 mm) and cover a broad range for both general and pressure-bearing applications.

6. Manufacturing Process for DIN 1629 Seamless Pipes

A modern three-stage process ensures precision and high performance:

Hot Rolling (~1000°C): Forms the base seamless tube.

Cold Drawing: Refines surface and dimensional accuracy.

Bright Annealing (~650°C for 4 hours): Relieves stress and enhances microstructure stability.

This process achieves yield strength≥235 MPa, elongation≥25%, and superior internal surface quality, meeting or exceeding DIN 1629 and EN 10216 requirements.

7. Applications of DIN 1629 Seamless Steel Pipe

DIN 1629 pipes are widely applied in:

Boiler and pressure vessel manufacturing

Petrochemical and refinery pipelines

Steam, gas, and water transmission lines

Hydraulic and mechanical systems

Steel structures and heavy machinery

Their high reliability, pressure tolerance, and clean internal surface make them ideal for critical industrial operations.

8. Conclusion

Despite being replaced by EN 10216, the DIN 1629 seamless steel pipe standard remains a benchmark for mechanical precision, pressure performance, and material quality.
It continues to guide St52.0 pipe suppliers, manufacturers, and engineers in ensuring safety, consistency, and performance across demanding applications worldwide.

Frequently Asked Questions (FAQ)

Q1: What is the difference between DIN 1629 and EN 10216?
DIN 1629 is the older German standard, while EN 10216 (especially EN 10216-1 and EN 10216-3) is its European successor.
EN 10216 introduces new grade designations and stricter testing requirements but retains similar mechanical performance to DIN 1629.

Q2: Is DIN 1629 St52.0 equivalent to ASTM A106 Gr. C?
Yes. DIN 1629 St52.0 roughly corresponds to ASTM A106 Grade C, both offering high tensile strength and suitability for high-pressure piping systems.

Q3: Can DIN 1629 seamless pipes be welded?
Absolutely. With controlled carbon content (≤0.22%), DIN 1629 pipes have good weldability, suitable for manual or automatic welding methods.

Q4: What industries commonly use DIN 1629 pipes?
They are used across energy, petrochemical, mechanical engineering, and construction sectors, especially for boilers, heat exchangers, and pipelines.

Q5: Are DIN 1629 pipes still in production?
Yes. While the standard itself is superseded, many manufacturers and suppliers still produce DIN 1629-compliant pipes to meet replacement and legacy system needs.