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wr@insulatedpipeline.com
wyy@insulatedpipeline.com
Published:2025-06-30 | Last Updated: 2025-06-30 Views: 3
“Fusion-bonded epoxy coated pipe” refers to pipes coated with a layer of fusion-bonded epoxy powder coating on the inner and outer surfaces of steel pipes. This coating is a very important pipe corrosion protection technology.
| Parameter Name | Description |
|---|---|
| Coating Type | Single-layer Fusion Bonded Epoxy (FBE) |
| Coating Thickness | Generally 100-250 micrometers (μm) |
| Pipe Material | Commonly used carbon steel (such as Q235, API 5L Gr.B, etc.) |
| Pipe Outer Diameter | Varies by specification, common range is 20mm-1420mm |
| Pipe Wall Thickness | Common range is 3mm-30mm |
| Temperature Resistance | Generally suitable for environments below 80°C |
| Bond Strength | ≥15MPa (ensures strong adhesion between coating and pipe) |
| Corrosion Resistance | Possesses good corrosion resistance, salt spray test ≥500 hours |
| Wear Resistance | Resistant to mild mechanical wear |
| Construction Performance | Suitable for on-site welding and cold bending processing |
| Component | Material/Process | Main Function | Thickness Range (Typical) |
|---|---|---|---|
| Pipe Base Material | Carbon steel or low-alloy steel pipe | To withstand the pressure, mechanical loads, and conveyed medium of the pipeline system. It is the foundation of the entire structure. | As per pipeline design requirements |
| Surface Pre-treatment Layer | Blast cleaning + chemical treatment | Core step: Thoroughly remove rust, scale, oil, dirt, and other contaminants from the surface of the steel pipe to achieve the specified surface cleanliness (e.g., Sa 2.5) and roughness (anchor pattern depth, e.g., 50-100 μm). | N/A (changes surface condition) |
| Fusion Bonded Epoxy Coating | Single-layer FBE: Standard fusion-bonded epoxy powder Double-layer FBE: Standard FBE layer + modified/toughened FBE layer | To provide the main corrosion barrier, isolating the steel pipe from the corrosive environment (soil, water, chemical media, etc.) and preventing electrochemical corrosion. | Single-layer: 250 - 500 μm Double-layer: Total thickness 500 - 1000 μm (bottom layer ~250 μm, top layer ~350-750 μm) |
| Joint Coating (Not part of the pipe body, but a key part of the pipeline system) | Liquid epoxy coating, heat shrink sleeve/tape, or FBE powder (requires special equipment) | To provide corrosion protection at the pipe welding joints (on-site or in the factory) that matches and is continuous with the pipe body coating performance. | Depends on material and requirements |
| Optional Functional Layer | Internal coating (FBE or other): For internal corrosion protection, drag reduction, anti-scaling. Identification coating: Provides pipeline identification information. | To meet specific application requirements (e.g., internal corrosion protection, identification, etc.). | Depends on requirements |
Steel pipe incoming inspection → Surface pretreatment (sandblasting for rust removal) → Surface cleanliness/roughness inspection → Steel pipe preheating (180–250°C) → Electrostatic spraying of epoxy powder → High-temperature melting and leveling (powder melting) → Curing and cross-linking (coating chemical reaction) → Water cooling/air cooling → Coating thickness inspection → Spark testing for pinholes → Adhesion testing (random sampling) → Appearance quality inspection → Marking spraying → Finished product packaging and storage
Detailed explanation of key processes:
| Step | Purpose | Technical Key Points |
|---|---|---|
| 1. Pipe Arrival Inspection | To ensure the base pipe is free of defects and meets dimensional requirements | Inspect welds, ovality, and wall thickness deviations |
| 2. Blast Cleaning | To remove scale and rust, creating an anchor pattern surface | Reach Sa 2.5 grade (ISO 8501), anchor pattern depth 50-100μm |
| 4. Preheating | To activate the powder's reactivity and promote fusion bonding | Precise temperature control (±5℃), avoiding local overheating |
| 5. Electrostatic Spraying | To ensure the powder is evenly adsorbed onto the pipe wall | Voltage 60-100kV, spray gun distance from the pipe 15-30cm |
| 6-7. Fusion and Curing | The powder melts into a film and cross-links to cure | 230℃±10℃, hold for 1-3 minutes (depending on coating thickness) |
| 10. Spark Testing | To detect micro-pores and defects in the coating | Testing voltage 5kV/mm (e.g., 2.5kV for a 500μm coating) |
| 11. Adhesion Testing | To verify the bonding strength of the coating | Cross-cut test (ISO 2409) or pull-off test (≥15MPa) |
(1) Exceptional Adhesion
Through high-temperature fusion curing, the coating forms a dual bond with the steel pipe via chemical bonding and mechanical anchoring.
Comparison: Superior to the physical adsorption of ordinary plastic-coated steel pipes, it is less prone to delamination.
(2) Long-Lasting Corrosion Protection Barrier
After curing, the coating is dense and pore-free, effectively blocking the penetration of water, oxygen, and ions.
Application: Widely used as the outer protective layer for buried corrosion-resistant spiral steel pipes, with a service life exceeding 30 years.
(3) Strong Substrate Adaptability
Can be directly applied to the surface of welded steel pipes (after sandblasting treatment).
Advantage: Compatible with various substrate forms such as straight seam welded pipes and spiral welded pipes.
(4) Balanced Mechanical Properties
High hardness (Shore D > 80), resistant to gravel impact, and superior wear resistance compared to plastic-coated steel pipes.
Limitations: Thickness is only 0.3–0.5 mm, with lower resistance to sharp object penetration compared to 3PE coatings.
(5) Electrical insulation and cathodic compatibility
Resistance > 10¹⁰ Ω·m, blocking corrosion currents; cathodic剥离 radius < 8 mm (65°C, 28 days).
Value: When combined with sacrificial anodes or impressed current protection, safety is significantly enhanced.
(6) Environmental Protection and Hygiene
Non-toxic and solvent-free after curing, certified for drinking water use under NSF/GB/T 17219 standards.
Comparison: Some plastic-coated composite steel pipes require additional inner linings to meet hygiene requirements.
(7) Construction Economy
Factory-prefabricated on an assembly line, with single-layer coating costs lower than those of double-layer epoxy-coated plastic-coated composite steel pipes.
Note: On-site joint repairs require specialized equipment; otherwise, they may become weak points.
(1) Energy Transportation Sector
Oil and Natural Gas Trunk Pipelines: 80% of onshore oil and gas long-distance pipelines worldwide use FBE external anti-corrosion coatings.
Subsea Pipelines: Resistant to seawater corrosion and cathodic剥离, ensuring the safety of subsea welded steel pipes.
(2) Municipal Water Supply Engineering
Drinking Water Transmission Networks: Compliant with NSF/GB 17219 hygiene standards, replacing galvanized pipes.
Wastewater/Reclaimed Water Networks: Resistant to microbial corrosion, addressing leakage issues in concrete pipes.
(3) Industrial Process Systems
Chemical plant process pipelines: Resistant to acidic and alkaline media (pH 3-11), protecting carbon steel welded steel pipes.
Slurry conveyance pipelines: Wear-resistant layer design (double-layer FBE), tripling service life.
(4) Special Application Scenarios
Directional drilling crossing sections: Double-layer FBE coating resists rock abrasion, used for river/road crossings.
Power plant circulating water pipes: Resistant to seawater corrosion and marine fouling, reducing maintenance costs by 60%.
(5) Structural Protection Applications
Cross-sea bridge pile foundation sleeves: Isolates chloride ion corrosion, extending the service life of steel structures.
Tunnel anchor bolt corrosion protection: Replaces traditional galvanized coatings, with a service life exceeding 30 years.
| Category | Material/Standard Name | Technical Key Points | Application Scenario |
|---|---|---|---|
| Base Pipe Material | Carbon Structural Steel Q235B (GB/T 700) Q345B (GB/T 1591) | Yield strength ≥ 235MPa, used for low-pressure water pipes/structural pipes | Municipal water supply, building pipeline networks |
| Pipeline Steel for Oil and Gas Transportation X42-X80 (API 5L/GB/T 9711) | Tensile strength ≥ 415MPa, sulfur content ≤ 0.015% (to prevent hydrogen embrittlement) | Petroleum and natural gas long-distance pipelines | |
| High-Pressure Fluid Pipe 20# Steel (GB/T 8163) | Seamless steel pipe base material, pressure resistance ≥ 10MPa | Chemical process pipelines | |
| Coating Material | General-purpose Epoxy Powder ISO 21809-2 Type 1 | Curing temperature 230±5℃, gel time ≤ 30s (at 180℃) | Conventional soil environment |
| Enhanced Epoxy Powder ISO 21809-2 Type 2/3 | Toughened and modified, impact resistance ≥ 10J (-30℃) | Rocky areas, subsea pipelines | |
| Sanitary-grade Epoxy Powder NSF/ANSI 61 GB/T 17219 | Heavy metal leaching ≤ 0.1mg/L, non-toxic certification | Potable water conveyance pipes | |
| Finished Pipe Standard | International Standard ISO 21809-2 (Petroleum industry) | Adhesion ≥ 15MPa, cathodic disbonding ≤ 8mm (65℃/48h) | Global oil and gas projects |
| Chinese Standard GB/T 23257-2017 (buried steel pipes) | Spark testing ≥ 5kV/mm, salt spray resistance ≥ 1000h | Domestic long-distance pipelines | |
| American Standard AWWA C213 (coated water pipes) | Porosity 0 (3kV testing), bending 3° without cracking | North American water utility projects | |
| Testing Method Standard | Adhesion Testing ISO 4624 (pull-off method) ASTM D6677 (cross-cut method) | Cross-cut method grade 0 (no delamination), pull-off method > 14MPa | Coating bond strength verification |
| Thickness Detection SSPC-PA 2 (magnetic thickness gauge) | Single-point thickness ≥ 300μm, up to 10% of measurement points may be below standard but > 250μm | Production quality control | |
| Chemical Resistance GB/T 1733 (acid-alkali immersion) | 30-day immersion in 10% HCl/NaOH solution, no blistering or delamination of the coating | Chemical environment applicability assessment |
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E-mail：wr@insulatedpipeline.com
E-mail：wyy@insulatedpipeline.com
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