Steel pipes are essential materials in construction, infrastructure, and industrial projects. Among the many types available, ERW pipes and GI pipes are two of the most commonly used. If you are planning a project and wondering which option is better, understanding the difference between ERW pipe vs GI pipe can help you make the right choice. In this article, we’ll explain what ERW pipes and GI pipes are, compare their features, highlight their applications, and guide you on which one to choose for your project.
What is ERW pipe?
ERW pipe (Electric Resistance Welded pipe) is manufactured by cold-forming a steel coil into a cylindrical shape and welding the edges together using high-frequency electric resistance, resulting in a strong weld seam and a smooth finish. With high dimensional accuracy, a smooth internal surface, and availability in various sizes and thicknesses, ERW pipes are strong, durable, and more economical compared to galvanized pipes. Thanks to these advantages, they are widely used in oil and gas pipelines, water transportation (when coated), structural frameworks in buildings, as well as scaffolding, fencing, and engineering projects. Their combination of cost-effectiveness and strength makes ERW steel pipes a preferred choice across industries that require reliable performance on a large scale.
Advantages of ERW pipe
1. High production efficiency and manageable costs
ERW pipe is made from steel strip through continuous roll forming and electric resistance welding. This eliminates the need for complex ingot piercing processes. This results in a short production cycle, high output, and high raw material utilization. Consequently, its cost is significantly lower than seamless steel pipe, making it suitable for large-scale batch applications.
2. Smooth inner wall for excellent conveying efficiency
The molding process ensures a highly flat inner wall with no noticeable protrusions or impurities. This reduces resistance to the flow of fluids (such as water, oil, and gas), minimizing pressure loss and making it particularly suitable for long-distance conveying.
3. Flexible Specifications and Wide Adaptability
We can produce pipes in various diameters (from small and medium to large) and wall thicknesses based on demand. These pipes can be combined with a variety of connection methods (welding, flanges, etc.), making them suitable for a wide range of applications, including oil and gas transportation, water supply and drainage, and steel structure support.
What is GI pipe?
GI pipe (Galvanized Iron pipe) is produced from mild steel pipes, often ERW or seamless, that are coated with a protective zinc layer through hot-dip or electro-galvanizing. This zinc coating safeguards the steel against rust and corrosion, making GI pipes highly suitable for outdoor and water-based applications. With excellent corrosion resistance, a longer lifespan in humid or harsh environments, a shiny silver appearance, and safe use in plumbing and water systems, GI pipes are easy to identify and highly reliable. They are widely applied in plumbing and water supply, irrigation and agriculture, outdoor piping and drainage, as well as firefighting systems and HVAC installations. Thanks to their durability and resistance to corrosion, GI pipes remain a preferred choice for projects where long-term performance in challenging environments is essential.
Advantages of GI pipes
Excellent Corrosion Resistance – The zinc coating protects the steel from rust, ensuring long-term durability even in humid or water-based environments.
Longer Service Life – Compared to plain steel pipes, GI pipes last significantly longer in corrosive conditions, reducing replacement and maintenance costs.
Safe for Water Supply – GI pipes are suitable for transporting drinking water, making them ideal for plumbing and municipal water distribution systems.
Strength and Reliability – Made from mild steel, GI pipes provide strong mechanical performance while benefiting from the added protection of galvanization.
ERW Pipe vs GI Pipe: Detailed Comparison
Aspect
ERW Pipe (Electric Resistance Welded Pipe)
GI Pipe (Galvanized Iron Pipe)
Definition
Manufactured by welding the edges of a steel coil using high-frequency resistance.
Steel pipe (often ERW or seamless) coated with a protective zinc layer.
Manufacturing Process
Cold-formed from steel coil → edges welded together → smooth finish.
Hot-dip or electro-galvanizing process adds a zinc coating to prevent rust.
Strength
Strong, durable, and suitable for structural and industrial applications.
Strong but primarily valued for its corrosion resistance.
Corrosion Resistance
Moderate – requires external coating or lining for outdoor/water use.
Excellent – zinc coating provides long-lasting protection against rust.
Appearance
Plain steel finish, can be painted or coated as needed.
Shiny silver finish due to zinc coating, easy to identify.
Cost
More economical; budget-friendly option.
Higher cost because of the galvanization process.
Applications
Oil and gas pipelines, scaffolding, fencing, structural frameworks, engineering projects.
Plumbing, water supply, irrigation, outdoor piping, drainage, firefighting systems, HVAC installations.
Which is Better: ERW Pipe or GI Pipe?
The choice between ERW pipe vs GI pipe depends on your project requirements:
Choose ERW pipe if you need strength, cost-efficiency, and structural reliability for industrial or construction use.
Choose GI pipe if your project involves plumbing, water distribution, or exposure to outdoor and corrosive environments.
In many cases, ERW pipes are galvanized to create GI pipes—so technically, GI pipes can be seen as a type of ERW pipe with additional zinc protection.
Read more: ERW Pipe vs. LSAW Pipe
