Can You Use Galvanized Pipe for Gas?

Can galvanized pipes be used for gas transmission?

Galvanized pipes (GI pipe) can be used for gas transmission in certain circumstances (low-pressure indoor gas pipelines), but they must comply with relevant gas pipeline standards and have usage restrictions. For outdoor buried or high-pressure gas pipelines, the use of ordinary galvanized pipes is strictly prohibited.

Permitted Use:
In traditional gas engineering, galvanized steel pipes were indeed widely used for low-pressure gas supply pipes within buildings, such as the branch pipes connecting hallway risers to your kitchen gas stove and water heater.

Advantages:
High strength: They can withstand certain physical impacts.
Corrosion resistance is better than that of black steel pipes: Compared to black steel pipes, the galvanized coating effectively resists indoor atmospheric corrosion and has a longer lifespan.

Reliable threaded connections: Threaded connections offer excellent sealing and mature technology.

Specification requirements: 

Strict compliance with the national "Urban Gas Design Code" and other standards is required. Use galvanized steel pipes specifically for gas use, which have specific requirements for material, wall thickness, and galvanized coating quality.

Situations where galvanized pipe is prohibited or gradually replaced:

Although its use was previously permitted, it has inherent drawbacks in gas applications. Therefore, it is being gradually replaced by better materials in new buildings and high-end projects.

1. Prohibited for use in outdoor buried pipes

Reason: Soil contains moisture, microorganisms, and various chemicals, making it extremely corrosive. Ordinary galvanized coatings cannot withstand long-term soil corrosion. Once the zinc coating is damaged, the steel pipe will quickly rust and perforate, leading to gas leaks and serious accidents.
Alternative: Outdoor buried gas pipelines must use PE polyethylene plastic pipe or 3PE corrosion-resistant steel pipe with a special anti-corrosion coating.

2. Disadvantages and alternative materials for indoor use

Even indoors, galvanized pipe has the following issues:
Susceptibility to rust at joints: Threading removes some of the galvanized coating, making the joint the weakest link in the rust barrier and prone to rust.
Complex installation: Threading and wrapping with raw tape are required, reducing installation efficiency.

Potential for zinc peeling: After long-term use, the zinc coating may peel off, clogging valves or stoves. 

Therefore, the most recommended materials for indoor gas piping are:

a. Stainless steel corrugated hose: This is currently the preferred choice for home use. It offers excellent flexibility, corrosion resistance, easy installation, and a long service life.
b. Thin-walled stainless steel pipe: Utilizing press-fit connections, it provides excellent sealing, overall corrosion resistance, and is aesthetically pleasing and durable.
c. Copper pipe: Offers stable performance and corrosion resistance, but is more expensive.

In the early days, hot-dip galvanized pipe was used for low-pressure gas transmission pipelines (such as residential indoor gas branches, with pressures ≤ 0.01 MPa). Its high strength and corrosion resistance met the requirements of low-pressure gas environments, and it was also easy to install. However, with rising gas transmission standards, higher-quality pipe materials, such as seamless steel pipe and PE pipe, are now increasingly used for medium- and high-pressure gas pipelines or in applications with extremely high safety requirements. The use of galvanized pipe is gradually declining. Key limitations include: Galvanized pipe connections are often threaded, which can corrode and leak at the thread seals over time, posing a safety hazard. Furthermore, rust on the inner wall of galvanized pipe can introduce impurities, affecting gas purity and even clogging gas meters and stoves.

If using galvanized pipes for gas transmission, ensure they are hot-dip galvanized. Cold-dip galvanized pipes are not suitable for gas transmission due to their thin zinc coating and poor adhesion. Furthermore, the pipe quality must be strictly inspected to ensure there are no defects such as zinc damage or cracks, and welds and joints must be tight. After installation, an airtightness test must be conducted and only used after passing the test to prevent gas leaks.

In addition, galvanized gas pipes must be regularly inspected for corrosion and the tightness of joints. If leaks are detected, they must be immediately removed from service and repaired. Currently, galvanized pipes are still used in some older residential communities for low-pressure gas branch pipes or temporary gas transmission.

Gas Pipe Installation Precautions:

If you need to install or modify gas pipes, please adhere to the following safety guidelines:
a. Unauthorized Modifications are Strictly Prohibited: Any installation, modification, or removal of gas pipes (including galvanized pipes) must be performed by a qualified professional gas company or construction team.
b. Use of Qualified Materials: The contractor must use specialized pipes and fittings that comply with gas regulations.
c. Regular Inspection: Existing galvanized gas pipes should be regularly inspected for rust, paint peeling, scratches, and other signs, especially at threaded connections. If severe rust is found, contact the gas company immediately for replacement.

Conclusion:

Galvanized pipes can be used for indoor gas distribution, but they are no longer the optimal choice. For safety, durability, and convenience, stainless steel corrugated hoses are currently the best choice for home gas distribution. In any case, gas pipe maintenance must be handled by professionals; safety always comes first.

Read more: Black Steel Pipe vs. Galvanized Steel Pipe