Galvanized pipe vs. ordinary steel pipe: rust resistance/pressure bearing capacity/lifespan comparison

The following is a comprehensive comparative analysis of galvanized pipes and ordinary steel pipes in terms of rust resistance, pressure bearing capacity and life, combined with key data and actual application scenarios:

1. Rust resistance comparison
Characteristics Galvanized pipe Ordinary steel pipe
Anti-corrosion principle The surface galvanized layer (usually 20-60μm) isolates oxygen and water No protective layer, directly exposed to the environment
Rust resistance Significantly better than ordinary steel pipes, can withstand general humid environments Easy to rust, especially in humid or acidic and alkaline environments
Key data When the thickness of the galvanized layer is ≥40μm, the outdoor rust resistance time can reach 20-30 years (without mechanical damage) Rust occurs in 1-2 years in exposed environments
Note: If the galvanized layer is damaged (such as cutting or welding), local rust will accelerate.

2. Comparison of pressure bearing capacity
Characteristics Galvanized pipe Ordinary steel pipe
Short-term strength Same as ordinary steel pipe of the same material (galvanizing does not change the strength of steel) Depends on the steel grade (such as Q235, Q345)
Long-term impact The galvanized layer delays corrosion and has better long-term pressure bearing stability. After corrosion, the effective wall thickness decreases and the pressure bearing capacity decreases
Key data The yield strength and tensile strength do not change before and after galvanizing (for example: the yield strength of Q235 steel pipe is 235MPa) When the corrosion depth is 0.1mm, the pressure bearing capacity decreases by about 5%-10%
Note: The pressure bearing capacity mainly depends on the wall thickness and material of the steel pipe, not whether it is galvanized.

3. Service life comparison
Characteristics Galvanized pipe Ordinary steel pipe
Typical environment Outdoor, humid environment (such as building scaffolding, guardrail) Dry indoor or short-term temporary use
Average life 15-50 years (depending on the quality of the galvanized layer and the environment) 5-10 years (regular anti-rust maintenance is required)
Cause of failure Rust of the substrate after the galvanized layer is exhausted Comprehensive rust leads to structural damage
Key cases:

Galvanized pipe: The service life in coastal areas (high salt spray) is about 15-20 years; in inland dry areas, it can reach more than 40 years.

Ordinary steel pipe: Industrial areas (sulfur-containing air) need to be replaced every 3-5 years.

4. Other comparison factors
Project Galvanized pipe Ordinary steel pipe
Cost 20%-50% higher price (including galvanizing process) Low cost, suitable for projects with limited budget
Welding performance The galvanized layer needs to be polished first, otherwise it is easy to produce pores Direct welding, simple process
Environmental protection The galvanizing process includes pickling and zinc pollution No galvanizing pollution, but rust products may pollute the soil

5. Selection suggestions
Galvanized pipes are preferred:

Long-term outdoor use (such as municipal pipelines, exposed building structures)

High humidity and salt spray environment (such as coastal areas, chemical plants)

Ordinary steel pipes can be selected:

Short-term projects or dry indoor environments (such as temporary brackets)

Scenarios where frequent welding is required and budget is limited

Maintenance tips: Ordinary steel pipes can extend their life by applying anti-rust paint, but the maintenance cost may exceed the initial price difference of galvanized pipes.

Summary
Galvanized pipes have absolute advantages in rust resistance and life, and are suitable for harsh environments; ordinary steel pipes are economical but require maintenance, and are suitable for short-term or low-corrosion scenarios. There is no difference in the pressure bearing capacity between the two in the short term, but they differ in the long term due to the degree of corrosion.