MS Pipe vs. GI Pipe vs. GP Pipe

MS, GI, and GP pipes are three of the most frequently compared and selected steel pipe types in construction engineering, manufacturing, furniture production, agricultural irrigation, and industrial structures. Although their base material is carbon steel, they differ significantly in surface treatment, corrosion resistance, service life, and applicable scenarios.

This article will provide a systematic and authoritative comparative analysis of the three types from the aspects of material definition, manufacturing process, performance characteristics, typical applications, and selection recommendations.

MS Pipe Full Form

Mild steel pipe is the full form of MS pipe, made of mild steel. They typically contain a small amount of carbon (approximately 0.05%–0.25%), making them softer and more ductile than high-carbon steel. This low carbon content gives mild steel pipe excellent weldability, ductility, and formability.

1. Manufacturing Process

Mild steel pipes are typically manufactured from hot-rolled or cold-bent steel strips, which are then processed into round, square, or rectangular cross-sections and welded along the weld seam. The welds are then heat-treated to ensure strength and uniformity.

2. Properties

High Strength: Provides robust performance for structural and mechanical applications.

Easy to Weld and Bend: Ideal for manufacturing and construction.

Cost-Effective: Lower initial cost compared to galvanized pipe.

Versatile Applications: Suitable for industrial and general engineering projects.

3. Applications

Building Framing: Used for columns, beams, and trusses.

Furniture Manufacturing: Commonly used for tables, shelves, and support frames.

Scaffolding Structures: Widely used for temporary construction platforms.

Industrial Support Systems: Ideal for machinery support and framing.

Pipe Fences: Used to build durable, easy-to-install barriers.

GI Pipe Full Form

GI pipe, also known as galvanized iron pipe, refers to steel pipe with a zinc protective coating. Essentially, it is mild steel pipe that undergoes hot-dip galvanizing to form a thick zinc layer. This coating prevents corrosion and rust caused by moisture or chemical attack.

1. Manufacturing Process

The galvanizing process involves immersing mild steel pipes in molten zinc, ensuring a strong zinc coating adheres to the steel surface. This coating acts as a physical barrier, preventing corrosion and providing sacrificial anodic protection, meaning the zinc layer corrodes before the underlying steel.

2. Properties

Excellent Corrosion Resistance: Ideal for applications exposed to water, moisture, or outdoor environments.

Longer Service Life: The zinc coating enhances durability and reduces maintenance costs.

High Tensile Strength: Strong enough for heavy-duty applications.

Leak-proof Fittings: Suitable for water supply and fluid transport systems.

3. Applications

Water Supply and Drainage Piping: Commonly used in residential and commercial systems.

Outdoor Construction: Ideal for buildings exposed to rain and sun.

Scaffolding Systems: Longer service life compared to ordinary carbon steel pipes.

Agricultural and Irrigation Systems: Suitable for reliable water supply and drilling piping.

GP Pipe Full Form

GP pipe is galvanized pipe, also known as galvanized flat pipe, is made by continuously electro-galvanizing cold-rolled galvanized steel sheets. Unlike hot-dip galvanized steel pipes, GP pipes use an electro-galvanizing process, resulting in a smoother, shinier, and more uniform surface.

1. Manufacturing Process

The raw material for GP pipes is cold-rolled coil, which is then electro-galvanized before being formed into pipes and welded. Due to strict process control, the final product has a uniform, thin zinc layer, providing excellent corrosion resistance for indoor and light outdoor applications.

2. Properties

Aesthetically Pleasing: Smooth and shiny surface, suitable for visible structures.

Corrosion Resistance: Provides moderate rust protection.

Lightweight: Easier to transport and handle than galvanized steel pipes.

Excellent Machining Performance: Ideal for precision machining.

3. Applications

Furniture and Accessories: Widely used in office and home furniture.

Automotive Frames: Suitable for body structures and light vehicle components.

Display and Storage shelving: A clean and aesthetically pleasing surface, ideal for commercial interior design.

General Processing: Suitable for any application requiring lightweight, clean steel.

MS Pipe vs. GI Pipe vs. GP Pipe

While all three types of pipe are made of steel, their main differences lie in their galvanizing process, corrosion resistance, and intended use.

1. Coating and Protection

MS Pipe: No protective coating; therefore, it is prone to rust when exposed to humid environments.

GI Pipe: Hot-dip galvanized, forming a thick zinc layer that provides excellent corrosion protection.

GP Pipe: Electro-galvanized, forming a thin, smooth zinc layer, suitable for aesthetic and lightweight applications.

2. Corrosion Resistance

Both GI and GP pipes offer superior corrosion resistance compared to MS pipes.

GI pipes, due to their thicker zinc layer, offer the highest level of protection, making them suitable for outdoor and water-related applications.

GP pipes, while also resistant to minor corrosion, perform best indoors or in low-humidity environments.

3. Appearance and Surface Finish

MS pipe has a dark gray, slightly dull appearance.

GI pipe has a matte silver-gray finish due to its hot-dip galvanizing process.

Galvanized steel pipe (GP pipe), on the other hand, has a bright silver appearance, making it more visually appealing for both indoor and outdoor installations.

4. Strength and Durability

All three types of steel pipe have high structural strength, but their service lives differ.

GI pipe typically has the longest service life due to its thicker galvanized coating.

While MS pipe is durable, it may require painting or regular maintenance to prevent rusting.

GP pipe has moderate strength and is best suited for light to medium-duty applications.

5. Compliance Standards

MS Pipe: ASTM A500 / EN 10219 / BS 1387 (Black Pipe)

GI Pipe: ASTM A53 / BS EN 10240 / IS 1239

GP Pipe: EN 10346 DX51D / JIS G3302

6. Cost Considerations

Mild steel pipe is the most economical. GI pipe is slightly more expensive due to its galvanizing process, while galvanized steel pipe is generally priced between the two, offering good protection and aesthetics within a reasonable price range.

7. Applications

MS Pipe: Construction, scaffolding, fencing, and furniture.

GI Pipe: Piping, outdoor structures, irrigation, and water supply piping. GP Pipe: Furniture, automotive frames, and decorative frames.

Common Misconceptions

Myth 1: GI Pipes Will Never Rust.

GI pipes only significantly delay corrosion through hot-dip galvanizing, not permanent rust prevention. When the zinc layer is worn away by long-term outdoor exposure, acid rain, or mechanical wear, the base steel pipe may still rust.

Ordinary outdoor environments: GI pipes can last 15–30 years. Highly corrosive environments (coastal areas, chemical industrial zones): Thicker galvanizing or use plastic-coated pipes/stainless steel is required.

Myth 2: GP Pipes and GI Pipes are the Same Pipe.

GP pipes are usually electro-galvanized or pre-galvanized steel pipes, while GI pipes are hot-dip galvanized steel pipes. There are significant differences in zinc layer thickness, corrosion resistance lifespan, and applicable environments.

Key Differences:

GP pipes: Thin zinc layer, bright surface, suitable for indoor use;

GI pipes: Thick zinc layer, strong corrosion resistance, suitable for outdoor use.

Myth 3: MS Pipes are of Poor Quality and Unsuitable for Engineering Use.

MS pipes (mild steel pipes) are not low-quality products, but they lack a surface anti-corrosion coating. In dry or paintable environments, MS pipes remain the mainstream choice for structural engineering.

Many building structures and industrial equipment frames still prioritize MS pipes, protected by painting or powder coating.

Myth 4: GP Pipes Can Replace Gi Pipes for Outdoor Use.

GP pipes can be used for short periods in mild outdoor environments, but due to their thin zinc coating, they are not suitable for long-term exposure to rain or high humidity.

Recommendation:

Temporary structures: GP pipes are acceptable;

Permanent outdoor projects: GI pipes must be selected.

Myth 5: All Galvanized Pipes are Suitable for Transporting Drinking Water.

Not all GI pipes meet drinking water standards. Whether they are suitable for drinking water depends on:

The applicable standards;

The quality of the zinc coating;

Compliance with local regulations (e.g., NSF/WRAS).

How to Choose the Right Steel Pipe for Your Project

1. Choose MS Pipe

When the project budget is limited and the steel pipe is used indoors or in structural applications that can be painted or rust-proofed, such as furniture, scaffolding, and general framing.

2. Choose GI Pipe

When the steel pipe is exposed outdoors for extended periods, in humid environments, or transporting water, such as water supply and drainage, irrigation, fencing, and outdoor structures.

3. Choose GP Pipe

When the project has high requirements for appearance, lightweight, and processing precision, and is primarily used indoors or in mildly corrosive environments, such as furniture and decorative structures.

If you are unsure which type of steel pipe best suits your needs, the technical experts at Eastern Steel Manufacturing Co., Ltd. can provide guidance based on your project's environment and design loads.

FAQ

1. Is surface treatment necessary for mild steel pipe?

Yes.

If mild steel pipe is exposed to air or humid environments, painting, oiling, or powder coating is necessary to prevent corrosion.

2. Can GP pipe be used for outdoor fencing?

Short-term or low-corrosion environments are acceptable, but long-term outdoor fencing is not recommended. For superior durability, GI pipes should be the preferred choice.