What is hot-dip galvanized ERW steel pipe?

What is hot-dip galvanized ERW steel pipe?

Hot-dip galvanized ERW steel pipe is the product of the combination of two mature processes. It is first made into a steel pipe through a resistance welding process, and then hot-dip galvanized to finally form a metal pipe with excellent performance. ERW (Electric Resistance Welding) stands for high-frequency resistance welding. This process heats and melts the edge of the tube blank through the skin effect and proximity effect of high-frequency current, and performs pressure welding under the action of the extrusion roller. Production can be achieved without the use of welding filler materials. Hot-dip galvanizing is to immerse the already formed ERW steel pipe in molten zinc liquid at about 500°C, so that a uniform zinc-iron alloy layer is formed on the surface of the steel pipe, giving the steel decades of anti-corrosion protection

Hot Galvanized Steel pipe is a pipe that has been dipped into a molten zinc bath. The layer of zinc provides a protective boundary, permitting steel to be used in moderately corrosive services and outdoors services.

Standards for hot-dip galvanized ERW steel pipes

Standards: ASTM A106, ASTM 53, API 5L, JIS P2311...
SHAPE: round, square and rectangular
OD: 21.3mm-219mm
WT: 0.5mm-12mm
Zinc Coating: 300-500g/m2, (42um-70um)
Applications: Construction foundation piles, steel structure building, structure pipe in construction.
Recommendation: JIS G3444, ASTM A53 A/B, BS1387, DIN2440, ISO65, ISO1461,GB/T 3091 etc.
Test pressure /Mpa: d10.2-168.3mm = 3Mpa;D177.8-323.9 mm = 5 mpa

Development history of hot-dip galvanized ERW steel pipe

From a historical perspective, ERW technology originated in the 20th century and has been continuously improved with the development of the power industry, while hot-dip galvanizing technology is even older. Since France first applied it to industry in 1836, it has a history of nearly two hundred years. The galvanized ERW steel pipe produced by combining these two processes has the dual advantages of efficient production and long-term corrosion protection. Internationally, especially in the United States, after years of technical research and development, the seamless technology of ERW steel pipe has made significant progress, including geometric seamlessness (removing internal and external burrs) and physical seamlessness (improving weld organization), which makes the performance of modern hot-dip galvanized ERW steel pipe comparable to that of seamless steel pipe, and even more advantageous in some application scenarios.

Compared with traditional seamless steel pipes, the main difference of hot-dip galvanized ERW steel pipes is that they have a longitudinal weld, which is also the key point of quality control. However, modern production processes have minimized the impact of this weld. ERW steel pipes are made of hot rolled coils and then welded using high frequency current. This method has the characteristics of high production efficiency, low cost, material saving and easy automation. Coupled with hot dip galvanizing, this type of steel pipe can meet various high and low pressure requirements when transporting gas and liquid objects such as oil and natural gas. At present, it has occupied a pivotal position in the field of transportation pipes in the world.

Hot Galvanized Steel Pipe Welding

In the first layer of multilayer welding weld, try to melt the zinc layer and make it vaporized, evaporation, this can greatly reduce the zinc liquid remained in the weld. The same method is used for fillet welds. First move the electrode tail forward about 5~7mm, and then return to the original position to continue welding after melting the zinc layer. If the choice of short slag electrode such as J427, there will be a very small bite edge tendency; Back and forth input electrode can get the welding quality without defect

Specifications of Hot-dip Galvanized ERW Steel Pipe

Product Name	Hot Dip Galvanized Steel Pipe/Pre-Galvanized Steel Pipe
Thickness	0.3mm-12mm
Length	5.5m, 5.8m, 6m, 11.8m, 12m etc , other length is Available according to demands
Diameter	15mm-219mm
Tolerance	Wall Thickness: ±0.05mm Length:±6mm Diameter: ±0.3mm
Shape	Round, Square, Rectangle, Oval etc.
Material	Q195,Q235, Q345, Q355, 10#, 20#, 45#, Gr.B-Gr.50, DIN-S235JR, JIS-SS400, JIS-SPHC, BS-040A10
Technique	ERW, Hot-rolled, Cold-rolled
Surface treatment	Hot dipped galvanized, pre galvanized, electro galvanized.
Zn Coating	Pre-galvanized steel pipe: 20-275g/m2 Hot dipped galvanized steel pipe: 180-500g/m2
Standard	ASTM, DIN, JIS,BS

With the advancement of technology and the accumulation of application experience, the application field of hot-dip galvanized ERW steel pipes is still expanding. On the one hand, the advancement of material technology and manufacturing processes enables hot-dip galvanized ERW steel pipes to meet more demanding application environments, such as sour natural gas transmission, deep-sea pipelines, etc.; on the other hand, the update of design concepts also makes engineers more inclined to choose this economical and reliable material solution. Especially under the modern engineering concept that emphasizes sustainable development and life cycle costs, hot-dip galvanized ERW steel pipes are highly favored for their long life, low maintenance, and recyclability. In the future, with the continuous investment in infrastructure construction in China and around the world, as well as the stable development of industries such as energy and water conservancy, the market demand for hot-dip galvanized ERW steel pipes will maintain a steady growth trend. Manufacturers need to pay close attention to the technological development of various application fields, continuously optimize product performance, and improve service quality to meet the diversified needs of the market.