What Are The Uses of ERW Boiler Tubes?

ERW boiler tube (Electric Resistance Welded Boiler Tubes) is a steel tube for boiler manufactured by resistance welding, mainly used to transport water, steam or other media under high temperature and high pressure environments. Its core feature is the use of resistance welding technology, which uses the heat generated by the electric current to melt the edges of the steel strip to form a tube, which has efficient production and cost advantages.

Manufacturing process

1. Steel strip pretreatment: Cold-rolled or hot-rolled steel strips are flattened and trimmed.

2. Forming and welding: The steel strip is curled into a tube, and the metal at the joint is melted by high-frequency current (HFW) or low-frequency current, and pressure is applied to complete the welding.

3. Post-processing: Heat treatment of the weld (such as normalizing) to eliminate stress, sizing, straightening, cutting, and finally non-destructive testing (such as ultrasonic, eddy current testing) and pressure testing.

Material selection

1. Common materials: Carbon steel (such as 20G, SA-178C), low alloy steel (such as Q345, 15CrMoG).

2. Standard specifications: Must comply with ASME SA-178 (carbon steel pipe), SA-192 (high-pressure boiler tube), GB 3087 (Chinese national standard), etc.

Performance characteristics

1. High strength: Materials and processes ensure pressure bearing capacity and adapt to the high-pressure environment of boilers.

2. Uniform welds: High-frequency welding makes the welds narrow and flat, reducing the risk of defects.

3. Dimensional accuracy: Cold rolling process ensures small tolerances for outer diameter and wall thickness (such as ±0.10mm).

4. Temperature resistance: Heat treatment improves creep resistance at high temperatures.

5. Economical: High production efficiency, lower cost than seamless pipe (reduced by about 20%-30%).

Application areas

1. Power plant boilers (large thermal power generation, nuclear power generation)

Water Wall: Thin wall (usually 3~8mm), high precision (outer diameter tolerance ±0.1mm), suitable for dense arrangement requirements. Materials such as SA-210C (medium carbon steel) or 15CrMoG (low alloy steel), temperature resistance up to 450~600℃.

Superheater and reheater: The material needs to be resistant to high temperature oxidation and creep, such as SA-213T11 (1.25Cr-0.5Mo steel) or T91 (9Cr-1Mo steel). The pipe diameter is small (φ25~50mm), the wall thickness is 4~8mm, and high-frequency welding ensures the uniformity of the weld.

Economizer: Carbon steel pipes (such as SA-178C) are used in medium and low temperature environments (200~400℃), and the serpentine pipe structure requires high bending accuracy.

2. Industrial boilers (chemical, textile, food processing, etc.)

Steam boilers: The material is mainly 20G (GB 3087) or SA-192 (ASME standard).

Hot water boilers: ERW carbon steel pipes (such as Q235B) are commonly used, and the surface is galvanized or coated for corrosion protection.

Waste heat recovery system: 09CrCuSb (sulfuric acid dew point corrosion resistant steel) is commonly used. The modular design relies on the size consistency of ERW pipes for quick installation.

3. Petrochemical and energy equipment

Refining unit heat exchanger: Generally requires 15CrMoG (H₂S corrosion resistance). Temperature 300~450℃, pressure 4~10MPa, weld normalizing treatment improves stress cracking resistance.

Coal chemical gasifier: Generally requires 12Cr1MoVG (high temperature creep resistance). Temperature 500~800℃, the outer wall is sprayed with silicon carbide wear-resistant coating.

LNG liquefied natural gas equipment: Generally requires 09MnNiDR (-196℃ low temperature impact toughness). Temperature -162℃, full pipe -40℃ Charpy impact test meets the standard.

4. Environmental protection and new energy facilities

Waste incineration boiler: The material is generally 2205 duplex stainless steel (resistant to Cl⁻ corrosion) and Inconel 625 cladding on the inner wall.

Biomass boiler: Generally requires TP347H (18Cr-10Ni-Nb, resistant to alkali metal vapor corrosion). Wall thickness 8~12mm, extending the replacement cycle in alkaline corrosion environment.

Solar thermal power generation: 316H stainless steel (resistant to 565℃ molten salt oxidation) is commonly used as the material. 100% radiographic detection (RT) of welds to ensure zero leakage of high-temperature molten salt.

5. Special industrial scenarios

Ship power boiler: EH36 marine steel (resistant to salt spray corrosion) is often used. The outer wall is coated with epoxy resin to adapt to the high humidity environment of the ocean.

Geothermal development wellbore: Used for geothermal well casing pipe and heat exchanger tube. Gr.2 titanium alloy (resistant to geothermal fluid Cl⁻ corrosion) is generally used.

Summary

ERW boiler tubes have become an indispensable and important material due to their efficient manufacturing process, superior performance characteristics and wide range of applications. From large power plant boilers to various special industrial scenarios, ERW boiler tubes meet the use requirements in different environments through precise size control, high-strength pressure resistance and excellent temperature resistance.