DIN 30671

Specifications for Thermoset Coatings on Buried Steel Pipes

1. Scope and Technical Principles

1.1 Standard Definition & Evolution

DIN 30671 Carbon Steel Welding Pipe Coating SpecificationDIN 30671 DSHA ( German Institute for Standardisation )_DIN coating pipe standardDIN 30671 is the standard specification for Cement Mortar Lining for ductile iron pipes and fittings for water application published by the Deutsches Institut für Normung (DIN) in 1998. Its complete name is “Thermoset plastic coatings for buried steel pipe.” This standard organizes the material selection, manufacturing procedures, and quality control requirements for thermosetting coatings used for the exterior protection of steel pipe lines in underground and/or underwater services. It was developed during the Post-World War II rebuilding in the middle of Germany where in the immediate years before World War II, there was a market for a long-term creation of a corrosion prevention renovation material which in this case could be shown in re-lining gas works and district heating pipe

Corrosion Protection Mechanism:

Service Life: >50 years in moderate soils (2-3× longer than asphalt coatings).

2. Material Systems & Requirements

2.1 Applicable Conditions

Media: Water, gas, crude oil, non-corrosive chemicals

Temperature: -30°C to +70°C (standard); up to 140°C (EN 10290)

Pipe Dimensions: DN 20 (1″) to DN 2000 (78″); WT ≥2.0 mm

Exclusions: Steam pipes (>120°C), UV-exposed sections, pH<4 or pH>10 soils

2.2 Coating Classification

3. Technical Requirements

3.1 Dimensional Tolerances

3.2 Mechanical/Chemical Performance

4. Quality Control & Testing

4.1 Mandatory Inspection Regime

Raw Material Certification:

FBE powder: Gel time 30-60 sec @120°C

PU: NCO content ±0.5%

Process Controls:

Surface prep: Sa 2.5 (ISO 8501-1); anchor profile 50-100 μm

Application:

FBE: 230±10°C electrostatic spray

PU: Substrate ≥ dew point +3°C

Final Verification:

Destructive Tests (per 4 hrs):

Peel adhesion

Cathodic disbondment

Bend test (2.5° bend, no cracking)

NDE:

Holiday detection (3.0 kV/mm)

UT thickness mapping (≤1m spacing)

Field Joint Requirements:

Peel strength ≥50 N/cm

Overlap width ≥50 mm

5. Engineering Applications

5.1 Case Study: Middle East Water Pipeline

Pipe: DN1200×12 mm with FBE (DIN 30671)

Challenge: Sandy soil +50°C temperature

Solutions:

Silane coupling agents → 40% adhesion increase

IR thermography (ΔT ≤±5°C during curing)

Validation: 85% adhesion retention after 15-yr accelerated aging

5.2 Delamination Failure (Sudan, 2015)

Failure: Coating blistering at field joints after 3 years

Root Cause:

Weld slag contamination (adhesion =18 N/cm)

Soil Cl⁻ >500 ppm → electrochemical corrosion

Corrective Actions:

Mandatory weld zone blasting (Sa 2.5)

Double-layer HDPE shrink sleeves

6. Standard Migration & Innovations

6.1 Current Replacements

6.2 Emerging Technologies

7. Technical Data Summary

Implementation Notes:

For seawater exposure, supplement with DNV-RP-F106 (30 MPa hydrostatic resistance).

Hydrogen service requires H₂ permeability ≤0.5 mL/m²/day (per ISO 15105-1).

Carbon footprint reduction: Electric curing reduces CO₂ by 60% vs. gas-fired ovens.