Urban Water Supply and Drainage Projects: How to Choose the Right Anti-corrosion Steel Pipes?

In the construction of urban drainage projects, the selection of steel pipe materials is a crucial step, directly affecting the project's durability, maintenance costs, and overall operational efficiency. Choosing the right anti-corrosion steel pipes for water supply and drainage projects can be considered from the following aspects:

1) Consider the Usage Environment

1. Water Quality

Analyze the characteristics of the water transported in the water supply and drainage project. For urban domestic water, the water quality is generally relatively stable, with moderate pH, but may contain small amounts of dissolved oxygen and chloride ions. In this case, steel pipes with ordinary anti-corrosion properties can be selected, such as those with an epoxy coal tar anti-corrosion coating.

If the water contains a high concentration of corrosive substances, such as industrial wastewater or seawater, then anti-corrosion steel pipes with stronger corrosion resistance are required. For example, for seawater water supply and drainage projects, steel pipes lined with plastic (such as polyethylene) or rubber can be considered, as these materials have good corrosion resistance to seawater.

2. Soil Conditions

Understand the soil properties of the pipeline laying area. Highly corrosive soils, such as acidic or saline-alkali soils, will significantly corrode steel pipes. In such cases, in addition to selecting steel pipes with good corrosion resistance, additional anti-corrosion measures such as cathodic protection can be considered.

For areas with complex geological conditions, such as the presence of rocks or quicksand, the strength and deformation resistance of the steel pipes must be considered, and appropriate steel pipe materials and wall thicknesses should be selected.

3. Temperature Variation

Consider the temperature variation range of the water in the water supply and drainage project. High water temperatures may accelerate the aging and damage of the anti-corrosion coating; therefore, high-temperature resistant anti-corrosion materials must be selected. For example, in hot water supply pipelines, steel pipes with high-temperature resistant anti-corrosion coatings or ceramic linings can be selected.

For cold regions, the freeze-thaw resistance of the steel pipes must also be considered, and steel pipe materials and anti-corrosion measures that can withstand low temperatures must be selected.

2) Evaluating Corrosion Resistance

1. Types of Anti-corrosion Coatings

Common anti-corrosion coatings include epoxy coal tar pitch, polyethylene, and polyurethane. Epoxy coal tar coatings offer good water and corrosion resistance at a relatively low price, making them suitable for general water supply and drainage projects. Polyethylene coatings provide excellent corrosion resistance, impact resistance, and abrasion resistance, making them suitable for harsh environmental conditions. Polyurethane coatings offer good flexibility and low-temperature resistance, making them suitable for water supply and drainage projects in cold regions.

The appropriate type of anti-corrosion coating should be selected based on the specific requirements and budget of the project. Simultaneously, attention should be paid to the quality of the coating and the construction process to ensure the integrity and adhesion of the coating.

2. Anti-corrosion Grade Requirements

The anti-corrosion grade of the steel pipe should be determined based on the importance and service life requirements of the water supply and drainage project. Generally, important projects or projects with long service lives require steel pipes with higher anti-corrosion grades. For example, for the main water supply and drainage pipelines of large cities, reinforced or extra-reinforced anti-corrosion steel pipes can be selected.

The anti-corrosion grade is usually determined by factors such as coating thickness, material properties, and construction quality. When selecting anti-corrosion steel pipes, the anti-corrosion grade test report provided by the manufacturer should be reviewed to ensure that the steel pipes meet the project requirements.

3. Corrosion Resistance Testing

Require the manufacturer to provide corrosion resistance test reports for the anti-corrosion steel pipes, including salt spray tests and immersion tests. These tests simulate the corrosion resistance of the steel pipes in actual use environments and evaluate the performance of the anti-corrosion coating.

Relevant standards and specifications, such as the "Code for External Corrosion Control of Steel Pipelines," can be referenced to evaluate the corrosion resistance of the anti-corrosion steel pipes.

3) Examining Steel Pipe Quality

1. Steel Pipe Material

Common steel pipe materials used in water supply and drainage engineering include carbon steel, alloy steel, and stainless steel. Carbon steel pipes are relatively inexpensive but have generally lower corrosion resistance; alloy steel pipes and stainless steel pipes have better corrosion resistance but are more expensive. Select the appropriate steel pipe material based on the actual conditions and budget of the project.

For projects with special requirements, such as water supply and drainage pipelines that need to withstand high pressure or high temperature, high-strength alloy steel or stainless steel pipes can be selected.

2. Steel Pipe Specifications and Dimensions

Select appropriate steel pipe specifications and dimensions, including outer diameter, wall thickness, and length, based on the design flow and pressure requirements of the water supply and drainage project. Ensure the dimensional accuracy of the steel pipes meets standard requirements to guarantee the installation quality and sealing performance of the pipeline.

Simultaneously, consider the weight and transportation costs of the steel pipes, selecting appropriate specifications and dimensions for ease of construction and installation.

3. Manufacturing Process and Quality Control

Understand the manufacturing process and quality control measures for the steel pipes. High-quality anti-corrosion steel pipes should employ advanced production processes, such as spiral welding and straight seam welding, to ensure weld quality and the overall strength of the steel pipe.

Manufacturers should have a comprehensive quality control system, rigorously inspecting and testing raw materials, the production process, and finished products to ensure the quality of the steel pipes meets standard requirements. Request quality assurance documents and test reports from the manufacturer to understand the quality of the steel pipes.

4) Consider Cost and Benefits

1. Initial Investment Cost

Compare the prices of different types of anti-corrosion steel pipes, including the price of the steel pipe itself and the cost of the anti-corrosion coating. Simultaneously, consider transportation and installation costs to comprehensively evaluate the initial investment cost.

Don't just pursue the lowest price; choose anti-corrosion steel pipes with a high cost-performance ratio. Steel pipes with excessively low prices may have quality problems, potentially leading to higher maintenance costs later. 

2. Service Life and Maintenance Costs

Consider the service life and maintenance costs of anti-corrosion steel pipes. Steel pipes with good corrosion resistance and reliable quality have a longer service life and relatively lower maintenance costs. Conversely, poor-quality steel pipes may require frequent replacement or repair, increasing the overall project cost.

Refer to the manufacturer's service life predictions and maintenance recommendations to assess the long-term benefits of different types of anti-corrosion steel pipes.

3. Environmental Performance

Choose anti-corrosion steel pipes with good environmental performance to reduce environmental impact. For example, some anti-corrosion coatings may release harmful substances during production and use, posing a threat to the environment and human health. Choosing anti-corrosion steel pipes that meet environmental standards is beneficial to sustainable development.

Conclusion: 

Selecting suitable anti-corrosion steel pipes for urban water supply and drainage projects requires comprehensive consideration of factors such as the usage environment, anti-corrosion performance, steel pipe quality, cost, and benefits. During the selection process, it is essential to fully understand the specific requirements and actual conditions of the project, conduct thorough communication and consultation with the manufacturer, and select the most suitable anti-corrosion steel pipes to ensure the safe and reliable operation of the water supply and drainage project.

Read more: China Carbon Steel Pipe Manufacturer & Supplier List or Seamless Pipe vs. Welded Pipe