Can ERW Pipes Replace Seamless Pipes?

Can ERW Pipe Replace Seamless Pipe? Under What Circumstances Can it not be Used?

Absolutely, but strict conditions must be met. In most non-critical situations, ERW (Electric Resistance Welded) pipe can replace seamless pipe, but its applicability depends on the specific application scenario, performance requirements, and technological development level. However, under critical operating conditions such as high pressure, high temperature, high corrosion, or high fatigue, it absolutely cannot replace seamless pipe.

Core Advantages: Why can it be used as a substitute?

Through technological advancements, ERW pipe has approached or even reached the performance level of seamless pipe in certain aspects, mainly due to:

1. Weld heat treatment: Modern ERW pipe welds undergo online normalizing treatment, resulting in a metallographic structure and mechanical properties that are consistent with the base material, eliminating weak points.

2. Non-destructive testing: 100% online ultrasonic/eddy current testing ensures no defects inside the weld.
3. Dimensional accuracy: ERW pipe offers more precise control over its outer diameter and wall thickness, resulting in better surface quality.

Therefore, under non-critical operating conditions, high-quality ERW pipes can serve as a reliable and economical alternative to seamless pipes.

When can they be used as a substitute?

With technological advancements, ERW pipes have effectively replaced seamless pipes in several fields, especially in the following areas:

1. Medium and Low-pressure Fluid and Gas Transportation

For water, air, low-pressure steam systems, and low-pressure fire sprinkler systems at room temperature, ERW pipes can replace seamless pipes due to their lower design pressure and temperature, offering a cost advantage. They can also replace seamless pipes when the medium is not highly corrosive or does not require high purity. Examples include pipelines transporting industrial water, compressed air, and HVAC systems, rather than strong acids, strong alkalis, or pharmaceutical-grade high-purity fluids.

2. General Structural and Mechanical Applications

For applications with stable loads and no severe alternating stress, such as building structures, bridges, static frames (machinery housings and structural frames), and vehicle manufacturing (e.g., car stabilizer bars, car driveshafts), where strength and precision requirements are not extremely stringent, and pipelines that do not need to withstand high-frequency vibrations or large pressure fluctuations, ERW pipes have become a common choice due to their excellent comprehensive mechanical properties and cost advantages.

3. Oil and Gas Industry

In the field of oil well pipes and other oil-specific pipes, the strength of high-strength ERW pipes has reached the level of seamless pipes, and because their production process is better matched with the small-batch, multi-variety needs of oil fields, the replacement rate is increasing. Examples include gathering and transportation pipes and structural ERW pipes used on or near the surface where pressure and risk are relatively low.

4. Applications Requiring Excellent Surface Quality and Dimensional Accuracy

ERW pipes use hot-rolled coils as raw materials, with small wall thickness tolerances and precise outer diameter control. Their surface quality is generally superior to seamless pipes, making them more advantageous in applications with high requirements for these indicators. 

5. Lightweight Demands in New Energy Vehicles and Other Fields

New energy vehicles have high requirements for lightweight and high-strength components. ERW pipes, through the use of special alloy steel and advanced processes, can achieve weight reduction while meeting strength requirements, offering significant advantages.

6. Standard Permissions
Project design specifications or relevant industry standards (such as ASME B31.1, B31.3) explicitly permit the use of "welded pipes."

7. Purchaser Approval
Formal written approval from the designer is required before replacement, along with sufficient material comparison data and the welded pipe manufacturer's qualifications.

Currently Difficult to Replace:

Despite the rapid development of ERW pipes, replacement remains challenging in high-end fields with extremely high performance requirements, such as extremely high-pressure conditions, high-temperature or drastic temperature fluctuation conditions, corrosive or high-purity media, conditions subject to alternating loads and fatigue, and critical safety components. Examples include:

1. Pressure-bearing equipment such as high-pressure boiler tubes and petrochemical pipelines
These fields have extremely high requirements for material purity, overall density, and resistance to high temperature and pressure. Currently, high-end seamless steel pipes are still considered more reliable in terms of overall performance in these aspects, and ERW pipes have not yet fully reached the level of replacement in core technologies.

2. Some mechanical structural components requiring high strength and high toughness
Although ERW pipes have excellent performance at room temperature, high-end seamless steel pipes may still be a more reliable choice for impact toughness in extreme low-temperature environments and for certain specific fatigue strength requirements.

3. High-end seamless steel pipe sector in the export market
Data shows that my country's overall seamless steel pipe exports are higher than welded pipe exports, especially in oil-rich countries, where there is still stable demand for high-end seamless steel pipes. This indicates that in the export market, the replacement of high-end seamless steel pipes by ERW pipes has not yet been achieved on a large scale.

As an ERW welded pipe manufacturer, our professional advice and operating procedures are as follows:

If you are considering a replacement, please follow these rigorous procedures with us:

1. Transparent operating information:
Please be sure to provide complete operating data, including: medium, design pressure/temperature, cycle frequency, relevant standards, and safety level.

2. Suitability assessment
We will conduct a rigorous assessment based on your situation and in accordance with standards. For example, calculate the maximum permissible working pressure of ERW pipe according to ASME B31.3.

3. Provide "Equivalent Strength Certificate"

If the assessment is feasible, we will provide detailed technical documentation for the alternative, including:
Material certificate (material equivalent to seamless pipe)
Weld heat treatment process report
Non-destructive testing report (proving the weld is defect-free)
Hydraulic/pneumatic pressure test report

4. Final Approval Authority
We will never make substitution decisions unilaterally. All alternatives must be submitted in writing to your design engineer or project manager for final approval and safety responsibility.

Conclusion: 

The replacement of seamless pipe with ERW pipe is an ongoing trend, especially in low- and medium-pressure fluids, gas transportation, structural pipes, oilfield auxiliary pipes, and general engineering fields. Its advantages lie in cost, efficiency, surface quality, dimensional accuracy, and lightweight. However, in extreme conditions such as high pressure, high temperature, and high corrosion, and in high-end seamless pipe applications with extremely high requirements for material integrity and purity, seamless pipe currently still dominates. In the future, with further breakthroughs in materials science and welding technology, the range of alternatives for ERW pipes is expected to continue to expand.

Read more: Schedule 80 Carbon Steel Pipe or ERW Pipe vs. Seamless Pipe Cost