ANTI-CORROSION STEEL PIPE

1. Product Overview

Anti-Corrosion Steel Pipe (External & Internal Coated Steel Pipe)

Anti-corrosion steel pipe is a factory-coated composite piping system that combines the high pressure-bearing strength of a steel base pipe with advanced polymer lining/coating. It is engineered to resist soil corrosion, moisture, chemicals, and cathodic disbondment in buried, submerged, and industrial environments. Typical systems include:

2. Specification & Dimensions

Small/medium: Φ21mm – Φ610mm

Large: Φ219mm – Φ3620mm (spiral/SSAW up to 3620mm)

FBE (single/dual): 250–500 μm

3PE normal class: 1.8–2.5mm total

3PE reinforced class: 2.5–4.5mm total

Internal epoxy: 300–600 μm

3PE: -40°C to +80°C (standard), up to 110°C (3PP/high-temp grade)

FBE: up to 150°C

3. Material & Steel Grades

GB/T 8163 (seamless)

GB/T 3091 (welded, fluid)

GB/T 9711 / API 5L (line pipe)

SY/T 5037 (spiral weld)

ASTM A53 / A106 / A252

4. Coating Structure

3PE (Three-Layer Polyethylene)

1. Layer 1 – FBE Primer: 80–150 μm, chemical bonding to steel
2. Layer 2 – Copolymer Adhesive: 170–250 μm
3. Layer 3 – HDPE Outer Jacket: 1.8–4.5 mm (by class & OD)
   
   

FBE (Fusion Bonded Epoxy)

• Single or dual layer, electrostatic spray, 250–500 μm
• Excellent adhesion, impact resistance, cathodic disbondment resistance
  
  

TPEP (Composite)

• External: 3PE (2.5–4.5mm)
• Internal: FBE epoxy (≥350 μm), hygienic grade for drinking water
  
  

5. Executive Standards

• GB/T 23257 — Polyethylene coating for buried steel pipelines
• SY/T 0413 — Technical spec for PE anti-corrosion coating
• DIN 30670 — Polyethylene coatings on steel pipes
• ISO 21809-1 — External coatings for buried/submerged pipelines (3LPE/3LPP)
• CSA Z245.21 — External polyethylene coating
• API RP 5L2 — Internal lining of line pipe
• CJ/T 120 / GB/T 28897 — Coated composite steel pipe for water
• AWWA C210 / C213 — Liquid epoxy / FBE for potable water
  
  

6. Surface Preparation & Process

• Shot blasting to Sa 2.5 (near-white metal), anchor profile 40–100 μm
• Mid-frequency heating of pipe body
• Electrostatic FBE spraying → adhesive extrusion → PE/PP wrapping
• End cutback (50–150mm) left bare for field welding, with prime-coated edges
• Cooling, spark testing, marking
  
  

7. Testing & Inspection

• Dimensional check (OD, WT, length, ovality)
• Base pipe hydrostatic / UT / RT inspection
• Coating thickness measurement (positional)
• Holiday (spark) test: 25kV class, zero pinholes
• Peel strength: ≥100 N/cm @ 20°C
• Impact resistance: ≥7 J/mm
• Cathodic disbondment: ≤6–8mm (standard test)
• Adhesion cross-cut / pull-off test
• MTC (EN 10204 3.1) + optional SGS/BV inspection
  
  

8. End Preparation

• Plain End (PE) / Beveled End (30°–35°)
• Threaded & Coupled (small diameter)
• Flanged ends (coating repaired or lined flange)
• Field joint: heat-shrink sleeve, liquid epoxy, cold-applied tape
  
  

9. Typical Applications

• Long-distance oil & gas transmission pipelines
• Buried municipal water supply & drainage
• Sewage & wastewater networks
• Chemical plant piping (acid/alkali media)
• District heating (with insulation combination)
• Offshore / subsea & directional drilling crossings
• Mining, piling, and corrosive soil installations
  
  

10. Packing & Delivery

• Bundle with steel strips, end protectors
• Coating contact surfaces wrapped with non-abrasive film
• Marking: OD, WT, coating type/class, heat no., standard, flow arrow
• Container (6m/12m) or bulk shipment