Advantages and disadvantages of carbon steel galvanized pipes

In the field of pipeline engineering, carbon steel galvanized pipes have attracted much attention due to their unique anti-corrosion performance and cost-effectiveness. Carbon steel galvanized pipes are pipes made by coating a layer of zinc (hot-dip galvanizing or electroplating) on the surface of carbon steel pipes. They are widely used in construction, water supply, fire protection, gas and other fields. Its core advantage is the improved anti-corrosion ability, but there are also some limitations. The following is a detailed analysis:

Advantages of carbon steel galvanized pipes:

1) Performance advantages

1. Strong corrosion resistance
Carbon steel pipes are galvanized to form a dense zinc layer on the surface, which effectively isolates the direct contact between steel and the external environment, thereby significantly improving its corrosion resistance.

As a sacrificial anode, the zinc layer preferentially reacts with oxygen and water (forming a dense ZnO/ZnCO₃ protective film) to delay the corrosion of steel pipes. It is suitable for humid, weak acid/alkali environments (such as outdoor and underground buried pipes), and its service life is 3~5 times longer than that of ordinary carbon steel pipes.

2. Mechanical properties
Carbon steel galvanized pipes have good mechanical properties and retain the high strength (compression and impact resistance), toughness and ductility of carbon steel. This enables carbon steel galvanized pipes to withstand greater pressure and impact, and are suitable for pressure-bearing pipes (such as fire water supply).

3. Processability
Carbon steel galvanized pipes are easy to process and install, and can be modified and connected (threaded or flanged) by welding, cutting, bending, etc., with strong compatibility. This reduces the difficulty of construction and improves construction efficiency.
The galvanized layer does not require on-site anti-corrosion treatment, and the construction efficiency is high.

2) Cost-effectiveness advantages

1. Raw material price
Compared with other metal materials, such as stainless steel and copper, the price of carbon steel raw materials is relatively low, which makes carbon steel galvanized pipes have obvious cost advantages.

2. Service life
Because carbon steel galvanized pipes have good corrosion resistance, their service life is relatively long. Under the same working environment, the service life of carbon steel galvanized pipes may be longer than other types of pipes, thereby reducing long-term maintenance costs. At the same time, the zinc layer is wear-resistant and can resist mechanical damage during transportation and installation.

3. Recyclability
Carbon steel galvanized pipes have good recyclability. Abandoned pipes can be recycled and reused to reduce resource waste and environmental pollution.

4. Wide range of applications
Civil: building water supply and drainage, HVAC pipes.
Industry: low-pressure gas transmission, cable protection sleeves.
Agriculture: irrigation systems, greenhouse brackets.

Disadvantages of carbon steel galvanized pipes:

1. Limited life of zinc layer
In strong acid (pH <6), strong alkali (pH > 12) or high salt environment (such as coastal areas), zinc layer corrosion is accelerated and may fail in 5 to 10 years.
After the zinc layer is worn or scratched, electrochemical corrosion will form locally, and anti-corrosion coatings need to be applied.

2. Poor high temperature performance
Compared with pipes made of some special materials, such as ceramic pipes, glass pipes, etc., carbon steel galvanized pipes have poor performance in high temperature environments. Under high temperature conditions, carbon steel galvanized pipes may have problems such as deformation and oxidation.
Zinc will oxidize and fall off at high temperatures (>200℃), losing its protective effect, so it is not suitable for steam pipes or high-temperature industrial scenarios.

3. Environmental and health issues
The galvanizing process may produce wastewater and waste gas (which needs to be handled in compliance).
When drinking water is transported for a long time, zinc ions may precipitate in trace amounts.

4. Increased welding difficulty
The galvanized layer will produce toxic zinc vapor during welding (ventilation protection is required).
The zinc layer at the weld is burned and requires secondary anti-corrosion treatment (such as zinc paint).

5. Appearance limitations
The zinc layer is prone to form white rust (basic zinc carbonate), which affects the appearance and needs to be cleaned regularly (such as exposed pipes in buildings).

6. Weight and volume

Compared with pipes made of lightweight materials such as plastic pipes and aluminum alloy pipes, carbon steel galvanized pipes are heavier and larger in volume. This increases the difficulty of transportation and installation, and also increases construction costs.

Recommendations for the use of carbon steel galvanized steel pipes:

Preferred scenarios:
1. Indoor water supply and drainage, fire sprinkler systems.
2. Low-pressure gas transmission (must meet standards).

Avoid use scenarios:
1. Strongly corrosive media (such as seawater, acid and alkali chemical pipelines).
2. Outdoor exposed pipelines with high temperature (＞200℃) or long-term ultraviolet exposure.

Alternative solutions:
1. Highly corrosive environment: use stainless steel pipes or plastic-lined composite pipes instead.

2. High-temperature environment: seamless carbon steel pipe + high-temperature resistant coating.

Read more: Hot-dip Galvanized Seamless Pipe Production Process or Black Steel Pipe and Galvanized Steel Pipe