Looking for reliable ISO 2531 / EN 545 / EN 598 Ductile Iron Pipes for your water supply or infrastructure project?
Factory Direct Pricing
DN80-DN800 Available
Fast Delivery Worldwide
MTC & Third-Party Inspection Support
Ductile Iron Pipe Manufacturer in China | ISO 2531 & EN 545 K7 K8 K9 DI Pipe Supplier
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Royal Steel Group is a leading supplier of high-quality ductile iron pipes in China, with products fully compliant with ISO 2531, EN 545, and EN 598 standards. Ductile Cast Iron Pipes possess excellent mechanical properties, corrosion resistance, and a long service life, and are primarily used in urban water supply, sewage transportation, agricultural irrigation, fire protection systems, and industrial piping projects.
Nominal sizes range from DN80 to DN2600, with over 50 wall thicknesses covering grades K7, K8, K9, C, and M. Cement mortar lining, galvanized coating, and various protective systems are available, and customization is possible to suit different application environments.
| Item | Specification |
| Product Name | Ductile Iron Water Pipe |
| Standards | ISO 2531, EN 545, EN 598 |
| Material Grade | EN-GJS-500-7 (GGG50) |
| Pipe Classes | K9, C25, C30, C40 |
| Diameter Range | DN80-DN800 |
| Length | 5.7m, 6m, Customized |
| Pressure Rating | PN10, PN16, PN25, PN40 |
| Joint Type | T-Type, K-Type, Flanged Joint |
| Manufacturing Process | Centrifugal Casting |
| Origin | China |
The dimensions below comply with major international standards (including ISO 2531, EN 545, EN 598, and ASTM requirements). Standard wall thickness classes (such as K9, C40, Sch40) and customized lengths are available upon request.
| Nominal Size (DN) | Nominal Size (Inch) | Outside Diameter (OD - mm) | Standard Length (m) | Joint Type Options |
| DN80 | 3" | 98 | 5.8 / 6.0 | T-Type / Flanged / Restrained |
| DN100 | 4" | 118 | 5.8 / 6.0 | T-Type / Flanged / Restrained |
| DN150 | 6" | 170 | 5.8 / 6.0 | T-Type / Flanged / Restrained |
| DN200 | 8" | 222 | 5.8 / 6.0 | T-Type / Flanged / Restrained |
| DN250 | 10" | 274 | 5.8 / 6.0 | T-Type / Flanged / Restrained |
| DN300 | 12" | 326 | 5.8 / 6.0 | T-Type / Flanged / Restrained |
| DN400 | 16" | 429 | 5.8 / 6.0 | T-Type / Flanged / Restrained |
| DN500 | 20" | 532 | 5.8 / 6.0 | T-Type / Flanged / Restrained |
| DN600 | 24" | 635 | 5.8 / 6.0 | T-Type / Flanged / Restrained |
| DN700 | 28" | 738 | 5.8 / 6.0 | T-Type / Flanged / Restrained |
| DN800 | 32" | 842 | 5.8 / 6.0 | T-Type / Flanged / Restrained |
| Property | Value |
| Tensile Strength | ≥ 420 MPa |
| Yield Strength | ≥ 300 MPa |
| Elongation | ≥ 10% |
| Hardness | ≤ 230 HB |
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Royal Steel Group -Ductile Iron Pipe Manufacturer China can provide customized quotations based on your project specifications.
✔ Water Supply Projects
✔ Sewage & Wastewater Systems
✔ Irrigation Networks
✔ Municipal Infrastructure Projects
Internal Lining
Portland Cement Mortar Lining
Sulfate Resistant Cement Lining
Ceramic Epoxy Lining
Polyurethane Lining
External Coating
Zinc Coating + Bitumen
Zinc-Aluminum Coating
Epoxy Coating
Polyurethane Coating
High Mechanical Strength
All our high-tensile forged components are precision-machined exclusively from premium domestic carbon steel and stainless steel bar stock — no exceptions.
Superior Corrosion Resistance
We offer two professional galvanizing finishes for durable, long-term anti-corrosion performance: hot-dip galvanizing (molten zinc immersion) and electroplating. Both deliver exceptional, lasting protection, and perform even better when paired with an additional paint coating.
Leak-Free Joint System
Our flexible push-fit joints create a fully tight, reliable seal. They also cut down installation time significantly and boost long-term pipeline stability for your projects.
Ultra-Long Service Life
Engineered for heavy-duty use, our products deliver a service lifespan of 50+ years with minimal maintenance required, delivering outstanding long-term cost efficiency for infrastructure projects.
Full Compliance with Global Standards
All products are manufactured in strict accordance with ISO 2531, EN 545 and EN 598 standards, fully meeting the technical requirements for water supply and wastewater public infrastructure projects worldwide.
1. Raw Material Smelting: High-Purity Steel Melting
We melt premium-grade pig iron and recycled steel raw materials using state-of-the-art induction and cupola furnaces. For quality control, we run continuous spectral analysis throughout the process to precisely regulate the chemical composition of core elements (C, Si, Mn, P, S). This strict control ensures consistent high spheroidization of the material, which directly delivers the finished product’s high tensile strength and elongation performance.
2. Centrifugal Casting: High-Speed Precision Molding
We use industry-leading, fully automated metal-mold centrifugal casting machines (globally advanced technology) to form dense, uniform pipe walls. During production, we monitor casting speed and cooling temperature in real time to eliminate internal flaws like air bubbles and inclusions, guaranteeing a consistent, high-quality metallurgical structure for every single pipe.
3. Heat Treatment: Continuous Annealing Process
All cast pipes pass through a computer-controlled continuous annealing furnace to fully eliminate internal stress generated during the casting process. This critical production step refines the material’s grain structure and converts the matrix to ferrite, which drastically boosts the pipe’s overall ductility and impact resistance for long-term heavy-duty use.
4. Hydrostatic Pressure Testing: 100% Individual Pipe Inspection
Before any coating is applied, every single pipe runs through our automated hydrostatic pressure testing bench for full inspection. We run continuous, rigorous high-pressure tests (up to 50 bar / 5.0 MPa, adjusted based on pipe nominal size) to guarantee 100% leak-free performance even under extreme operating conditions.
5. Cement Mortar Lining: Internal Anti-Corrosion Protection
We apply cement mortar linings using a high-speed centrifugal spraying process, with material options including Portland cement, sulfate-resistant cement, and high-alumina cement to match different project requirements. The finished inner surface is fully smooth and compliant with ISO 4179 standards: it delivers a low friction coefficient to maximize hydraulic flow efficiency, while also preventing scale buildup and long-term internal corrosion.
6. External Zinc Coating: Outer Layer Corrosion Protection
Right after the annealing process, we thermally spray 99.99% pure zinc onto the pipe’s entire outer surface. Our standard coating weight meets a minimum of 130g/m² or 200g/m², fully aligned with ISO 2531 requirements. This creates a reliable electrochemical sacrificial anode layer that effectively protects pipes against soil corrosion during underground installation.
7. Asphalt & Epoxy Topcoat Application
On top of the base zinc coating, we apply a protective outer layer: choose from eco-friendly black asphalt paint, or thick-film liquid epoxy/polyurethane (including arctic-grade cold-resistant options for low-temperature regions). We use an automated spray curing system to guarantee a uniform dry film thickness (DFT) of no less than 70 microns, creating a robust, long-lasting barrier against harsh, aggressive soil environments.
8. Final Dimensional & Visual Inspection
Our team conducts a full end-to-end inspection covering all critical pipe specifications: length, wall thickness, outer diameter (OD), socket dimensions, and ovality. All checks are carried out exclusively by our independent QA/QC team, using calibrated digital calipers and ultrasonic thickness gauges. This strict verification ensures perfect alignment and seamless connection during on-site installation.
9. Secure Packaging & Global Shipping
First, we fit all pipe sockets and outlets with protective end caps or rubber rings. All pipes are then securely bundled using steel strapping and wooden padding to avoid in-transit damage. We design custom loading plans for both container shipments and bulk carrier transport, with strict handling protocols in place to eliminate the risk of coating scratches or physical impact during sea freight to any port worldwide.
Over 10 years of steel export experience
Factory-direct pricing
Full range of DN80-DN800 Ductile Steel Iron Pipe
Strict ISO quality control system
Fast production and global delivery
OEM and customized solutions available
SGS, BV, and third-party inspection support
Complete export documentation service
Pipes are securely packed with steel straps, wooden supports, and protective end caps to prevent damage during transportation.
Available shipping methods:
20GP / 40GP Containers
Break Bulk Vessel
Bulk Cargo Shipment
Export destinations include North America, Mexico, Central America, South America, Southeast Asia, the Middle East, and Africa.
Q1: What standards do your ductile iron pipes comply with?
A: All our Ductile Iron Pipe and Fittings are manufactured in strict compliance with ISO 2531, EN 545, and EN 598 international standards, fully meeting the technical requirements for global water supply and wastewater infrastructure projects.
Q2: What pipe classes are available?
A: We offer a full range of pipe classes to match different project load requirements, including K9, C25, C30, and C40.
Q3: Can you provide third-party inspection?
A: Absolutely. We support full third-party inspection services from globally recognized institutions including SGS, BV and TUV, and can issue official corresponding inspection certificates as required.
Q4: What coating options can be supplied?
A: We provide multiple coating solutions tailored to different application scenarios: standard zinc + bitumen, zinc-aluminum alloy, epoxy, and polyurethane coatings are all available.
Q5: Can customized lengths be manufactured?
A: Yes, we fully support customization. We can produce pipes with custom lengths and accommodate other special project requirements, all based on your provided drawings and technical specifications.
Q6: What documents can you provide?
A: We can provide a complete set of export documents upon request, including MTC (Material Test Certificate), inspection reports, packing lists, commercial invoices, and certificates of origin. All documents will be prepared to align with your local customs clearance requirements.
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