Differences between ERW and EFW steel pipe

ERW pipes are steel pipes that melt the edges of steel strips through resistance heating and then apply pressure to form weld seams. EFW pipes are made by melting the base material and filler metal through high temperatures generated by electric arcs or electron beams and then welding them together, which belongs to fusion welding. Although their names are similar, they have significant differences in manufacturing processes, welding methods, applicable materials and application fields.

What is ERW steel pipe?

ERW steel pipe is a welded pipe made by heating the edge of the steel strip to a plastic state through resistance heat and then welding it under pressure. This welding method does not require welding wire or filler metal and belongs to solid-phase welding. The weld seam is smooth, with high strength and high production efficiency.

Main features
The weld seam is smooth and has high dimensional accuracy
Suitable for carbon steel and low alloy steel
It has a relatively low cost and is suitable for mass production
The heat-affected zone of welding is small and the mechanical properties are stable

Common standards include: ASTM A53, API 5L, ASTM A252, EN 10219.
It is mainly applied in fields such as oil and gas transmission pipelines (medium and low pressure), structural steel pipes, scaffolding pipes, mechanical manufacturing and automotive parts.

What is EFW steel pipe?

EFW steel pipes are made by melting and welding the base material and welding wire together using an electric arc or an arc plus filler metal fusion welding method. EFW is typically used for welding thick-walled tubes made of stainless steel, nickel alloys and carbon steel. The weld seam is wide, with a large penetration depth and strong corrosion resistance, making it suitable for high-temperature and high-pressure environments.

Main features
The filler metal is used, and the weld seam is completely penetrated
Suitable for large-diameter and thick-walled pipes
It has excellent corrosion resistance and high-temperature strength
Each tube needs to undergo X-ray or RT inspection

Common standards include: ASTM A312, ASTM A358, ASTM A671, and ASTM A672.
It is mainly applied in fields such as chemical equipment, petrochemical plants, boiler and power plant pipeline systems, nuclear power, Marine engineering, and high-temperature and high-pressure fluid transportation.

ERW vs EFW: materials, sizes, and standards

Feature	ERW steel pipe	EFW steel pipe
Typical materials	Carbon steel, low-alloy steel	Stainless steel, nickel alloys, carbon steel and other specified alloys
Common grades	ASTM A53, API 5L grades and other applicable carbon steel grades	ASTM A358 stainless steel grades, ASTM A671/A672 carbon and alloy steel grades, and other applicable materials
Typical size range	Commonly used for standard and medium pipe diameters; actual range depends on the product specification	Often selected for specialized, large-diameter or thick-wall welded pipe; actual range depends on the specification and manufacturing process
Wall thickness	Commonly available in standard wall and schedule-based thicknesses	Can accommodate specialized and thicker-wall requirements depending on the applicable specification
Welding method	Electric resistance welding using resistance-generated heat and pressure	Electric fusion welding using an electric arc, with filler metal where required
Common standards	ASTM A53, API 5L and other applicable specifications	ASTM A358, ASTM A671, ASTM A672 and other applicable specifications
Typical applications	Water transmission, structural applications, mechanical systems, and oil and gas pipelines	Chemical processing, petrochemical facilities, power generation and specialized industrial piping
Main selection factors	Material, diameter, wall thickness, standard, pressure, temperature and inspection requirements	Material, diameter, wall thickness, standard, pressure, temperature, corrosion conditions and inspection requirements

How to choose the right welded steel pipe?

If the project requires medium and low pressure fluid transportation or structural pipes, ERW steel pipes should be selected: they have high production efficiency, beautiful welds and low cost.
If it is used in high-temperature, high-pressure or corrosive medium environments (such as in the chemical, energy, Marine and other fields), EFW steel pipes should be selected: they have high weld quality, strong corrosion resistance and higher reliability.

Choosing the appropriate type of steel pipe can not only enhance the safety of the project but also effectively reduce long-term maintenance costs.

Frequently asked questions

1. Is EFW better than ERW?

Not necessarily. EFW and ERW are different welding processes, and neither is universally better. The appropriate choice depends on the material, dimensions, applicable standard, service conditions and inspection requirements.

2. Is ERW pipe suitable for high-pressure applications?

Yes, ERW pipe can be used for high-pressure applications when the applicable product standard, material grade, wall thickness, testing and design requirements are satisfied. Pressure capability cannot be determined from the welding process alone.

3. Is EFW pipe always made with filler metal?

No. EFW is a fusion-welding process, and filler metal may be used when required by the welding procedure. The use of filler metal depends on the material, joint design and applicable specification.

4. Can ERW pipe be used for oil and gas pipelines?

Yes. ERW pipe is used in many oil and gas pipeline applications, including products manufactured to applicable pipeline specifications such as API 5L. The suitability depends on the required grade, dimensions, testing and service conditions.