Gain Insight Into the Difference Between ERW and EFW Pipe

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Two prevalent manufacturing methods in the pipe industry are Electric Resistance Welding (ERW) and Electric Fusion Welding (EFW). Both processes involve shaping flat steel into pipe form using a series of rollers and dies. However, the key distinguishing factor lies in how the edges of the steel plates are fused together.

This article will explore the distinct characteristics of ERW and EFW, detail their benefits, and guide you on when to use each type of piping.

ERW vs EFW Pipe: Forming Process

During the pipe formation, the alignment and joining of the two edges define the difference between ERW and EFW. In the ERW process, high-frequency electrical currents heat the edges just before the rollers join them into the final pipe shape. This high-frequency method is favored in modern applications due to its effectiveness in minimizing defects such as seam corrosion and inadequate bonding.

ERW pipes feature a weld seam running along their length. Depending on production techniques, this seam may be cleaned or trimmed or simply smoothed to match the outer diameter of the pipe, resulting in a visible seam inside.

In contrast, the EFW process employs an electron beam (or laser) to melt the edges before they are pressed together, leading to a weld seam that is typically cleaned on both the outside and inside. EFW pipes are recognized for their robust strength and durability, making them better suited for high-pressure and corrosive environments than ERW pipes.

Benefits of ERW

The ERW manufacturing method boasts high efficiency and cost-effectiveness. Its equipment is widely available, and with continuous maintenance, can sustain long operational lifespans, which is why it dominates pipe production in the plumbing, HVAC, and gas industries.

Benefits of EFW

The fusion method used in EFW results in a narrower heat-affected zone compared to ERW, providing better metal uniformity and higher pressure ratings. Although the initial investment might be higher for EFW, it presents a cost-effective alternative in applications requiring higher pressure ratings or corrosive resistance, making it a suitable substitute for seamless pipe in many conditions.

Common Applications of ERW Pipe

Given its versatility, ERW pipes find applications across various industries, including plumbing, HVAC, fire suppression, automotive, aviation, and energy sectors.

Common Applications of EFW Pipe

On the other hand, EFW pipes serve as cost-effective alternatives in sectors demanding prevention against high-pressure and corrosive conditions, such as petrochemicals, textiles, and food processing industries.

Specifications

ERW Pipe Specifications

• Sizes range from ½” to 48”.
• Manufactured in various schedules, from schedule 5 to schedule 160, depending on application needs.
• Common alloys include stainless steel and carbon steel.
• Industry standards include ASTM A178 for electric-resistance-welded carbon steel and carbon-manganese steel boiler and superheater tubes.

EFW Pipe Specifications

• Sizes range from 1/8” to 100” based on ASTM specifications.
• Manufactured in various schedules such as schedule 10, schedule 40, and schedule 80.
• Available in multiple alloys including stainless steel and carbon steel.
• Industry standards include ASTM A672 for electric-fusion-welded steel pipe used in high-pressure service.

Understanding the differences between ERW and EFW pipes is essential for ensuring the correct application in your projects. Factors such as pressure, corrosiveness, and budget should guide your selection. Always consult with engineering professionals before making any decisions regarding pipe installation.

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