Can galvanized pipes be used for gas transmission?

Galvanized pipes (GI pipes) can be used for gas transmission under specific conditions, mainly for low-pressure indoor gas pipelines. However, they must strictly comply with gas pipeline standards and face significant usage restrictions. For outdoor buried pipelines or high-pressure systems, the use of ordinary galvanized pipes is strictly prohibited.

Permitted Applications of Galvanized Pipe

In traditional gas engineering, galvanized steel pipes were once widely used for indoor low-pressure gas supply, such as branch lines from risers to kitchen stoves or water heaters.

Advantages of Galvanized Pipe

High strength → Withstand certain physical impacts.

Better corrosion resistance than black steel → Zinc coating offers protection against indoor atmospheric corrosion.

Mature threaded connection technology → Reliable sealing with proven application history.

Specification Requirements of Galvanized Pipe

Must comply with national standards (e.g., Urban Gas Design Code).

Only use hot-dip galvanized pipes designed for gas applications, with strict requirements on material, wall thickness, and zinc coating quality.

Situations Where Galvanized Pipes Are Prohibited or Being Replaced

1. Outdoor Buried Gas Pipelines

Problem: Soil moisture, microorganisms, and chemicals cause severe corrosion. Once the zinc layer is damaged, rapid rusting and perforation may lead to gas leaks and safety hazards.

Alternative: Use PE polyethylene pipes or 3PE anti-corrosion steel pipes with specialized coatings.

2. Indoor Applications – Drawbacks and Alternatives

Even indoors, galvanized pipes present several issues:

Rust at threaded joints → Thread cutting removes zinc layer, making joints vulnerable.

Complex installation → Requires threading and sealing tape, reducing efficiency.

Zinc peeling risk → Detached zinc particles may clog valves, meters, or stoves.

Recommended alternatives for indoor gas systems:

Stainless steel corrugated hoses → Preferred for households; flexible, corrosion-resistant, easy to install, and long service life.

Thin-walled stainless steel pipes → With press-fit connections; excellent sealing, durability, and aesthetics.

Copper pipes → Stable and corrosion-resistant, though costlier.

Historical Context and Decline in Usage

Early stage: Hot-dip galvanized pipes were widely used for low-pressure gas transmission (≤0.01 MPa).

Transition: With higher safety standards, seamless steel pipes and PE pipes are now the mainstream choice for medium- and high-pressure gas pipelines.

Key limitations:

Threaded joints prone to leakage.

Internal rust may contaminate gas, affecting purity and blocking equipment.

Safety Requirements for Galvanized Gas Pipes

If galvanized pipes are used:

Must be hot-dip galvanized (cold-dip types are not acceptable due to weak coating).

Pipes must be free of zinc coating defects, cracks, or weld flaws.

Airtightness tests are mandatory before use.

Regular inspections are required to detect corrosion, peeling, or joint leakage.

Gas Pipe Installation Safety Guidelines

No unauthorized modifications → All work must be carried out by licensed gas professionals.

Use qualified materials → Ensure compliance with gas safety standards.

Routine inspections → Especially at threaded joints; if serious rust is found, replace immediately.

Conclusion

While galvanized pipes can still be used in certain low-pressure indoor gas systems, they are no longer the optimal choice. For modern residential and industrial gas projects, stainless steel corrugated hoses, press-fit stainless steel pipes, or PE pipes provide superior safety, durability, and ease of installation.

Bottom line: GI pipes are a part of gas engineering history, but in today’s high-standard gas systems, they are being replaced by more advanced and safer materials.