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Steel Water Pipe commonly refers to carbon steel pipe (CS pipe) used for water supply. These pipes are typically made of carbon steel and are mainly used for transporting tap water, industrial water, and agricultural irrigation water. Carbon steel itself has limited corrosion resistance; therefore, protective coatings are applied to the inner and outer surfaces to isolate the water, prevent rust, avoid secondary pollution, and withstand high-pressure water flow and low temperatures.
Coated carbon steel pipes combine good corrosion resistance, high pressure resistance, reliable structural strength, and relatively simple installation and maintenance.
Steel water pipes are typically manufactured by cold-forming steel strip or plate into a tubular shape, followed by welding (SSAW, LSAW, or ERW). After welding, an anti-corrosion coating is applied to the inner and outer surfaces by spraying or centrifugal casting, followed by cooling and curing.
Unprotected carbon steel pipes face several problems in water supply service:
1. Pipe corrosion and perforation – can cause leaks, bursts, and supply interruptions.
2. Yellow water pollution – rust and heavy metal leaching threaten water quality.
3. Reduced transport capacity – scale and rust increase resistance and energy consumption.
4. Shortened lifespan – unprotected buried pipes may need replacement within a few years.
A suitable coating system isolates the steel from water and soil, extends service life, and maintains water quality.
Coating selection depends on water quality, pressure, pipe diameter, soil conditions, and budget. The table below shows the recommended coating direction for each factor. ▶ For a full comparison of 3PE, FBE, 2FBE, and cement mortar linings, see [Coated Carbon Steel Pipe: Types (FBE, 3PE) & Applications].
| Selection Factor | Considerations | Recommended Coating Direction |
|---|---|---|
| Water quality | Drinking water, industrial water, irrigation water | Epoxy lining (NSF 61 compliant) for drinking water; cement mortar lining for large-diameter raw water |
| Design pressure | Maximum working pressure, water hammer | Higher pressure requires thicker wall and reinforced external coating |
| Pipe diameter | Small/medium vs large diameter | Epoxy for small/medium; cement mortar for large diameter |
| Soil corrosivity | Buried soil resistivity, chloride content, stray currents | 3PE coating for highly corrosive soil; epoxy coal tar for moderate conditions |
| Budget and lifespan | Initial cost vs life-cycle cost | Cement mortar for cost-effective long-distance delivery; epoxy for premium water quality |
● Pipe ends: PE, BE (30°–35°), flanged, grooved.
● External coating: 3PE/3LPE, FBE, epoxy coal tar.
● Internal lining: liquid epoxy, FBE, cement mortar.
● Standards: AWWA C200, C205, C210, C213, NSF 61, ISO 21809, DIN 30670.
● Pressure: PN0.6–2.5 MPa, up to 4.0+ MPa; Class 150/300.
● Testing: 100% hydrostatic (1.5× nominal); NDT upon request.
▶ For steel pipe dimensions (NPS sizes, wall thickness, OD/ID, tolerances), see our [AWWA C200 Steel Water Pipe Dimensions].
| Coating Type | Internal Coating Standard & Thickness | External Coating Standard & Thickness | Reference Standards |
|---|---|---|---|
| Epoxy Resin Internal Coating | Liquid Epoxy / Epoxy Powder, ≥250μm | Double-Layer FBE / Epoxy Coal Tar, ≥400μm | AWWA C210, GB/T 18593 |
| Cement Mortar Lining | Thickness: 6–12mm (depending on pipe diameter) | Epoxy Coal Tar / Thick-Layer Epoxy, ≥300μm | AWWA C205, GB/T 17456 |
| External Corrosion Protection – Reinforced Grade | — | Three-Layer PE (3PE), Total Thickness ≥2.5mm | DIN 30670, GB/T 23257 |
The following AWWA standards apply to carbon steel water pipes and their coatings.
| Standard | Scope | Key Requirements |
|---|---|---|
| AWWA C200 | Steel water pipe, 6 inches and larger | Materials, manufacturing, testing |
| AWWA C205 | Cement mortar lining, 4 inches and larger | Factory-applied cement mortar lining and coating |
| AWWA C210 | Liquid epoxy lining and coating | Factory and field-applied liquid epoxy systems |
| AWWA C213 | Fusion bonded epoxy (FBE) | FBE lining and coating |
| NSF 61 | Drinking water contact materials | Sanitary certification for coatings and linings |
| Pressure Rating | Working Pressure | Typical Application |
|---|---|---|
| PN0.6 | 0.6 MPa | Low-pressure water supply |
| PN1.0 | 1.0 MPa | General water supply |
| PN1.6 | 1.6 MPa | Medium-pressure water supply |
| PN2.5 | 2.5 MPa | High-pressure water supply |
| Custom | ≥4.0 MPa | High-head, long-distance transmission |
Coated carbon steel water pipes are used across multiple water supply scenarios.
1. Municipal drinking water – strict water quality, NSF 61 required; epoxy lining is preferred.
2. Industrial water supply – cooling water, process water, high pressure; epoxy lining with external anti-corrosion coating.
3. Agricultural irrigation – large diameter, long distance, cost-sensitive; cement mortar lining with external anti-corrosion.
4. Water conservancy / raw water – raw water transmission, reservoirs; cement mortar lining.
5. Fire protection – fire water mains, sprinkler systems; epoxy or cement mortar lining.
Steel water pipe systems commonly use cement mortar lining for large-diameter transmission, while epoxy lining is preferred for smaller-diameter drinking water mains.
1. Regular cleaning – maintain clean water quality and normal pipeline operation.
2. Drain unused pipes – if a steel water pipeline is not used for a long time, drain it to avoid bacteria and scale growth.
3. Careful welding – when welding or processing, control heating and stress to avoid damaging the coating.
4. Safe handling and storage – avoid collisions or extrusion during transport and installation to prevent coating damage.
Hunan Standard Steel Co., Ltd (HSCO) provides high-strength CS pipe solutions for water supply projects. Our steel water pipes meet AWWA C200/C205/C210 standards and can be supplied with NSF 61 compliant linings for drinking water.
● Strict coating standards – internal and external coatings meet AWWA and GB requirements.
● Sanitary compliance – relevant sanitary permits and drinking water contact material certifications available.
● Structural performance – high pressure resistance for long-distance, high-head water transmission.
● Cost-effective – low maintenance costs and economical total cost of ownership.
● Construction adaptability – pipe welding, flange connection, and various joint types.
Q1: Which coating is suitable for drinking water pipes?
A: Internal coatings must meet drinking water standards such as NSF 61 or GB 5749. Liquid epoxy and cement mortar lining are common choices. For strict water quality requirements, epoxy lining is preferred.
Q2: What AWWA standards apply to steel water pipes?
A: AWWA C200 covers steel water pipe manufacturing, C205 covers cement mortar lining, C210 covers liquid epoxy, and C213 covers fusion bonded epoxy (FBE). NSF 61 certification is required for drinking water contact materials.
Q3: What is the maximum pressure rating for steel water pipes?
A: Standard products cover PN0.6 to PN2.5 MPa. Higher pressures up to 4.0 MPa and above can be customized based on wall thickness and material. All pipes undergo 100% hydrostatic testing at 1.5 times the nominal pressure.
Related Resources:
● ANSI/AWWA C200 Steel Water Pipe
● FBE & 2FBE Coating for Steel Pipe
● 3PE Coated Steel Pipe: Structure, Advantages & Applications
● SSAW Steel Pipe for Water Pipeline
● Packaging Methods of Anti-corrosion Spiral Steel Pipes
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