What is the difference between ERW and EFW?

Difference Between ERW and EFW Pipes

ERW (Electric Resistance Welded) pipes are made by rolling a flat strip of steel into a cylindrical shape and then using high-frequency electric current to heat the edges. These heated edges are pressed together to form a continuous weld seam without any filler material. This creates a strong bond through the metal’s own material.
EFW (Electric Fusion Welded) pipes employ a fusion welding method—often using an electron beam, electric arc, or other fusion techniques—to melt the edges of the steel before joining them. This process creates a weld seam through melting and fusion, which typically results in a stronger, denser, and more uniform joint compared to ERW.

ERW welding produces a narrow heat-affected zone (HAZ), which leads to good uniformity and toughness in the weld seam, often close to the properties of the base metal.
EFW welding yields an even narrower HAZ and a more consistent and stronger bond, giving EFW pipes higher pressure capacity and better durability.

ERW is typically used for thinner-walled pipes and is known for efficient, cost-effective production. It is a predominant method in industries such as plumbing, HVAC, fire suppression, automotive, aerospace, rail, electronics, energy, and general industrial applications.
EFW is better suited for thicker-walled pipes and demanding environments. It’s often used in fields such as petrochemical, chemical processing, food processing, and other high-pressure or corrosive systems—serving as a cost-efficient alternative to seamless pipe.

ERW manufacturing requires simpler and more common machinery, making it highly efficient and cost-effective.
EFW involves more complex welding equipment and processes, which generally makes it more expensive. However, its superior pressure rating and strength make it a competitive choice in tough applications.

Feature	ERW (Electric Resistance Welded)	EFW (Electric Fusion Welded)
Welding Method	Resistance welding, high-frequency current	Fusion welding using arc, electron beam, etc.
Heat-Affected Zone	Narrow, good weld uniformity	Narrower, stronger and denser weld
Material Thickness	Thin-walled applications	Thick-walled, high-strength applications
Cost & Equipment Complexity	Lower cost, simpler machinery	Higher cost, more complex equipment
Typical Applications	HVAC, plumbing, general industrial use	Petrochemical, chemical, high-pressure pipelines
Pressure Strength & Durability	Solid performance, lower than seamless	High pressure, robust—often an alternative to seamless

Use ERW when your project requires cost-efficiency, fast production, and works well with thinner-walled pipe—such as for standard plumbing, HVAC, or structural support.
Use EFW when you need high strength, and durability, and are dealing with high pressure, corrosive environments, or thicker walls—like in petrochemical or industrial pipeline systems.