A Guide to ERW, GP, GI & MS Pipes and Tubes

There are some important differences in the dimensions, manufacturing methods, and applications of ERW Pipes, GP Pipes, GI Pipes, and MS pipes and tubes.

ERW stands for Electric Resistance Welded. These pipes and tubes are made by rolling metal sheets and welding them longitudinally. ERW pipes typically have a visible weld seam and are produced from steel coils or strips, with diameters up to 24 inches.

Jizhong manufactures high-quality ERW pipes using high-frequency induction welding (HFIW) for sizes up to 21 inches in OD. This process cold-forms steel into a cylindrical shape and fuses it using an electric current—no filler material needed.

ERW pipes are primarily used for low to medium-pressure applications such as transporting water, oil, or gas. These pipes are available in bare or coated finishes and can be processed on-site to meet specific customer requirements.

Jizhong is a global supplier, exporting ERW pipe and tube solutions to more than 100 countries and regions across North America, Europe, the Middle East, Southeast Asia, and Africa.

GI stands for Galvanized Iron. GI pipes are coated in zinc through hot-dip galvanizing, offering protection against corrosion. They’re lightweight, affordable, and easy to handle. According to IS 1239 standards, GI pipes are color-coded to indicate grade.

GP means Galvanized Plain. These pipes are made from electro-galvanized carbon steel sheets and offer a better surface finish than GI pipes. The zinc layer helps prevent rust and corrosion. GP pipes are commonly used in home plumbing systems, especially in buildings constructed before the 1960s.

MS refers to Mild Steel. These pipes contain less than 0.25% carbon, making them softer and easier to form. MS pipes are widely used in plumbing, HVAC, fire protection, and general engineering projects.

MS Black Pipes (non-galvanized) are also popular for welding and general structural applications due to their affordability and long service life in well-maintained environments.

Jizhong offers a full range of round, square, and rectangular ERW/MS tubes with diameters from 0.19 mm to 152.4 mm, suitable for both industrial and structural applications.

Steel pipes are produced by either a welded or seamless process. Many factories integrate automated production systems into their pipe processing workflows to enhance production efficiency. In welded pipe production, flat steel strips are formed into a tube and the edges are fused using one of the following ERW methods:

1. High-Frequency Welding

Induction Welding: Uses magnetic fields to heat the pipe without direct contact.
Contact Welding: Transfers electricity via contact tips on the steel surface, ideal for thicker or larger-diameter pipes.

2. Rotary Contact Wheel Welding
Uses rotating contact wheels to apply both electric current and pressure at the weld point. It’s suitable for small-diameter or internally coated tubing where internal impeders can’t be used.

Steel pipes and tubes are essential across industries:

• Construction: Used in piling, scaffolding, and building frameworks.
• Infrastructure: Water, oil, and gas transport lines.
• Furniture and Interiors: Due to their strength and workability.
• Marine, Aerospace, and Industrial Plants: Thanks to their corrosion resistance and durability.

Jizhong pipes are trusted globally for critical applications—from refineries and skyscrapers to offshore facilities and high-load structures.

Jizhong offers scaffolding tubes in both hot-rolled (black) and galvanized finishes:

• Wall Thickness: 3.2 mm / 4.0 mm
• Outer Diameter: 48.3 mm
• Conforming to EN 39, EN 10219, BS1139 standards

Square Tubes (HR & Pre-Galv): Sizes from 16×16 mm to 120×120 mm
Rectangular Tubes: From 20×15 mm up to 100×60 mm
Available in multiple gauges, shapes, and finishes.

Q: What’s the full form of GI Pipe?
A: Galvanized Iron Pipe

Q: What does ERW mean?
A: Electric Resistance Welded

Q: What is MS Pipe?
A: Mild Steel Pipe

Q: What’s the difference between GI and GP Pipes?
A: GP is electro-galvanized, providing a smoother finish; GI is hot-dip galvanized and more rugged.

Jizhong is committed to delivering top-tier steel pipe and tube solutions with advanced manufacturing capabilities. Our dedication to innovation and international quality standards allows us to meet the unique demands of customers in over 100 countries worldwide.