Table of content
Introduction
Black steel pipe and galvanized pipe are common steel pipes used in industrial systems. If you work in plumbing or construction, you’re undoubtedly familiar with these two types of pipe. However, there are differences in their use. Newcomers to this industry need to understand the differences in their applications and performance to make the best choice and application.
What is the Difference Between Black Steel and Galvanized Pipe?
Black steel pipe generally refers to steel pipe produced without any anti-corrosion or rust coating. It is primarily used in gas and heating systems.
Galvanized steel pipe is typically coated with zinc after production, making it more corrosion-resistant. It is primarily used for plumbing and outdoor applications.
What Is Stronger, Black Steel Pipe or Galvanized Pipe?
Structurally, the two types of steel pipe are very similar. They are both made from steel; the main difference lies in the anti-corrosion coating. Galvanized pipe has a corrosion-resistant zinc coating that effectively prevents rust and corrosion. Therefore, it is used in humid or corrosive environments.
Black steel pipe lacks a protective coating and is therefore not typically used in humid or corrosive environments.
Quick Comparison:
| Feature | Black Steel Pipe | Galvanized Pipe |
|---|---|---|
| Base Material | Carbon steel | Carbon steel |
| Surface Coating | None | Zinc coating |
| Rust Resistance | Low | High |
| Structural Strength | High | High |
| Appearance | Matte black | Shiny silver-gray |
Will Black Steel Pipe Rust Outside?
Yes. Black pipe is more susceptible to rusting outdoors or in humid environments.
Because it lacks an additional coating, it:
- It is more susceptible to rusting outdoors or in environments exposed to frequent rain.
- It also requires a coating to protect the steel pipe when used underground.
- For this reason, black pipe is often used indoors or in gas pipelines.
Is Galvanized Steel Stronger Than Black Steel?
Based on mechanical properties, the two are comparable. However, when comparing corrosion resistance, galvanized steel has a significant advantage.
This means:
- Galvanized steel lasts longer in humid or acidic environments.
- The galvanized layer corrodes first, extending the service life of the original steel pipe.
- It is often used in water supply systems and outdoor installations.
What are the disadvantages of black steel?
Black steel pipe is affordable and durable, but it does have some drawbacks.
Key Disadvantages:
- It is prone to rusting in humid environments.
- It is not suitable for water supply systems.
- If used in outdoor environments, it may rust and cause blockages over time.
- It is not suitable for outdoor or underground environments.
- When using it, it is important to select the appropriate application.
What is Black Steel Pipe Used For?
Common uses for black steel pipe include:
- Oil and gas piping systems
- Propane gas piping
- Dry-type fire sprinkler systems
- HVAC and heating systems
- Welded framing and furniture
It is primarily used indoors and in applications where high corrosion resistance is not required.
What is Galvanized Pipe Used For?
Galvanized steel pipe is highly corrosion-resistant and is primarily used in the following applications:
- Water supply systems
- Outdoor handrails or fencing
- Underground piping systems
- Wet fire sprinkler systems
- Industrial piping systems
- Building framing, etc.
It is important to note that prolonged use of galvanized steel pipe in water supply systems can cause zinc leaching and accumulation, which can be harmful. Therefore, galvanized pipe is generally not used in drinking water systems.
Black Steel vs. Galvanized Pipe: Cost Comparison
The price difference between the two types of steel pipe is not significant, primarily because they are made from the same raw materials. The main difference is that one is galvanized and the other is not.
Price Comparison (approximate):
| Pipe Type | Price (per foot) |
|---|---|
| Black Steel | $1.20–$2.00 |
| Galvanized Steel | $2.00–$3.50 |
Therefore, galvanized steel pipe is slightly more expensive than black steel pipe because of the zinc coating. However, the zinc coating effectively protects the pipe, extending its service life. Taking all factors into consideration, the costs of the two are roughly the same.
Why Can’t You Use Galvanized Pipe for Gas?
It is generally believed that galvanized pipe cannot be used in gas systems. What are the specific reasons?
The reasons are as follows:
- The zinc coating on galvanized pipes is at risk of fading over time. If this happens, it can clog the regulator, impacting performance.
- Gas pipes are dry and do not require additional corrosion and rust resistance.
- Building regulations also clearly stipulate that galvanized pipe cannot be used in gas pipes.
Summary
The above describes the differences between black steel pipe and galvanized pipe and their respective advantages and disadvantages. A brief summary is as follows:
Black pipe is uncoated, less corrosion-resistant, and prone to rust. However, it is more affordable and can be used in gas pipes and dry environments.
Galvanized pipe has a zinc coating, offering stronger corrosion resistance and rust resistance, but is slightly more expensive than black pipe. It is primarily used in water supply systems and in some humid and acidic environments.
