DIN 2458
In-depth analysis of DIN 2458: Technical specifications and engineering applications
I. Standard Overview & Background
DIN 2458 WELDED STEEL PIPES AND TUBESSpecifies the technical delivery conditions for two qualities, TR1 and TR2, of welded tubes of circular cross section, with specified room temperature properties, made of non-alloy quality steel… This standard applies to weldable fine grain structural steels as well as apparatus steels. First published in mid-20th century and developed/expanded since, this standard covers both seamless and electric resistance welded tubes including tubes for bending and for flanging purposes as well as other products from high tensile carbon steel and alloy steel.
Standard Scope & Positioning:
Scope:For Oil and Gas Transmission Pipe tubes, produced by the electric resistance welding (ERW) method, longitudinal submerged arc welded (LSAW), and helical submerged arc welded (HSAW). Does not cover seamless or precision tubes (e.g. DIN 2393/2394).
Technical Delivery Conditions: An integrated part of this standard are DIN 1626 (welded tubes of non alloy steels), DIN 17172 (StE 290.7 to StE 360.7), DIN 17177 (StE 290.7 TM to StE 360.7 TM), DIN 17178 (GStE 290.7 TM to LStE 360.7 TM), DIN 17179 (StE 290.7 to LStE 360.7), and DIN 17120 (StE 290.7 to StE 360.7).
Core Value:
Consistency: Establishes dimensions, tolerances, and performance criteria, simplifying engineering.
Safety: It specifically prescribes the mechanical properties and testing to avoiad pipeline failures (leakage or fracture).
II. Product Application Scope
Application Fields
Transport of Fluid :Under low and middle pressure pipe line, transportation of water, gas, and oil (design pressure generally @10MPa).
Structural construction: Scaffolding, Bridge, Pile (works with stiffness and compressive strength).
Energy Devices: Boiler casing tubes, heat exchanger supports (Operating temperature: ≤350°C)
Environmental Limitations
Temperature: Normal range from 20°F to 572°F Additional impact testing required for temperatures below 0°F.
Aggressive Environment: Needs other coating (for example 3PE, galvanized, cathodic protection).
III. Dimensions & Tolerances
1. Dimension Ranges
| Parameter | Range | Unit |
| Outside Diameter (OD) | 10.2 mm – 2020 mm | mm |
| Wall Thickness (WT) | 1.6 mm – 20 mm | mm |
| Length | Fixed length (≤12 m) or random length | m |
2. Key Tolerances
| Parameter | Tolerance Requirement | Condition |
| Outside Diameter | ±0.5% (min. ±0.5 mm if OD ≤50 mm) | All sizes |
| Wall Thickness | ±10% nominal (local min. ≥80% nominal) | Avoids local weak points |
| Ovality | ≤1% nominal OD | Any cross-section |
| Length | ±2% or ±50 mm (whichever is greater) | Fixed-length pipes |
Note: High-precision applications (e.g., hydraulics) require additional control of inner diameter tolerance (±0.1 mm).
IV. Material & Performance Requirements
1. Chemical Composition (Typical Grade St 37.2)
| Element | Content (wt%, max.) | Function & Impact |
| Carbon (C) | ≤0.17 | Provides strength; excessive C impairs weldability |
| Phosphorus (P) | ≤0.050 | Impurity; induces low-temperature brittleness |
| Sulfur (S) | ≤0.050 | Causes hot cracking; limits segregation |
| Nitrogen (N) | ≤0.009 | Requires aluminum addition (≥0.020%) for fixation |
2. Mechanical Properties (Grade St 37.2)
| Property | Requirement | Test Standard |
| Yield Strength (Rₑₕ) | ≥235 MPa (for WT ≤16 mm) | DIN EN ISO 6892 |
| Tensile Strength (Rₘ) | 340 – 510 MPa | DIN EN ISO 6892 |
| Elongation (A₅) | ≥25% (longitudinal specimen) | DIN EN ISO 6892 |
| Impact Energy (KV) | ≥27 J @ 20°C (longitudinal V-notch) | ISO 148-1 |
Technical Note: Yield strength is the critical stress at which permanent deformation begins; Impact energy indicates resistance to sudden fracture, requiring higher values for low temperatures.
V. Test Methods & Quality Control
1. Mandatory Tests
Destructive Tests:
Tensile Test: 2 specimens per melt/heat batch to verify yield/tensile strength.
Impact Test: Mandatory sub-zero impact testing (e.g., -30°C) for service below -20°C.
Flattening Test: Weld must withstand flattening until walls contact without cracking (verifies weld ductility).
Non-Destructive Testing (NDT):
Hydrostatic Test: Pressure ≥1.5x design pressure (max. 90% of yield strength).
Ultrasonic/Radiographic Testing: Alternative to hydro test; detects lamination and weld defects.
2. Surface & Coating Verification
Holiday Detection: 25 kV spark test (zero holidays permitted).
Coating Adhesion: Cross-cut test (ISO 2409), Grade 0-1 acceptable.
VI. Comparison with Other Standards
| Parameter | DIN 2458 | API 5L | ASTM A53 |
| Primary Use | General industrial pipes | Oil & gas pipelines | Low-pressure fluid service |
| Strength Grade | St 37.2 (≈235 MPa) | X42-X80 | Gr B (≈240 MPa) |
| Size Range (OD) | 10.2–2020 mm | 10.3–1625 mm | 1/8″–26″ (3.2–660 mm) |
| Impact Requirement | Mandatory @ 20°C | Mandatory for PSL2 | Optional |
Engineering Implication: DIN 2458 offers lower cost for construction/low-pressure systems, while API 5L is superior for high-pressure energy pipelines.
VII. Typical Engineering Cases
Water Pipeline (Chile, 2021):
DIN 2458 St 37.2 pipe (DN 406.4 mm, WT 7.92 mm) lined internally with 3PE for drinking water utility.
Building Scaffolding (Egypt, 2020):
ERW pipe (OD 48.3 mm, WT 3.2 mm), yield strength 235 MPa, for large railway station buildings.
Boiler Casing (India, 2023)
St 37.0 nahtloses Rohr (Außen Ø 33,7 mm, Wanddicke 22 mm), temp. beständig bis 300°C, schützen der Überhitzer.Superheater tube.
Conclusion: Technical Positioning & Evolution
DIN 2458 serves as a foundational standard for general-purpose welded steel pipes, with core value in:
Flexibility & Economy: Wide size range (DN 6–2000) and moderate strength (St 37.2) cover most low-pressure scenarios at 15–20% lower cost than API 5L.
Quality Assurance: Full-chain testing from chemistry to impact toughness ensures >30 years service life.
Evolution Path:
Convergence with EN 10219 (European welded tube standard), enhancing low-temperature toughness clauses.
Adoption of digital QC (e.g., blockchain traceability of batch test data).
