Common Boiler Tube Sizes and Applications

As a key component in boiler systems, boiler tubes play an important role in bearing pressure, conducting heat, and transporting media during the heat energy conversion process. Depending on the operating temperature, pressure level, and operating environment, boiler tubes are widely used in industries such as power, metallurgy, chemicals, and petroleum. This article will introduce the sizes, classifications, and specific uses of common boiler tubes to help readers gain a deeper understanding of the characteristics and application scenarios of these steel tubes.

1. Definition and Classification of Boiler Tubes
Boiler tubes are steel pipes specifically used to manufacture boiler heating surfaces, steam transport systems, and pipelines operating in high-temperature and high-pressure environments. Based on the manufacturing process and operating environment, boiler tubes can be divided into the following categories:

Ordinary boiler tubes (low- and medium-pressure boiler tubes): Used in boilers with operating pressures below 5.88 MPa and temperatures not exceeding 450°C.

High-pressure boiler tubes: Used in high-temperature and high-pressure environments, with operating pressures reaching above 9.8 MPa and temperatures above 450°C.

Ultra-high-pressure boiler tubes: Suitable for specialized applications involving ultra-high temperatures and pressures, such as nuclear and thermal power plants.

Seamless boiler tubes and welded boiler tubes: Based on the processing method, seamless tubes are more commonly used in high-pressure boilers due to their greater pressure resistance.

II. Common Boiler Tube Dimensions and Specifications
Boiler tube dimensions primarily include outer diameter, wall thickness, and length. Commonly used standards include GB 3087 (seamless steel tubes for low- and medium-pressure boilers), GB 5310 (seamless steel tubes for high-pressure boilers), and international standards such as ASTM A192, A210, and A213.

1. Outside Diameter (OD)
Common boiler tube OD ranges mainly fall into the following specifications:

Common OD (mm) Application
25mm Small boilers or heat exchanger systems
32mm Water walls for medium- and low-pressure boilers
38mm Convection tube bundles and headers for medium- and large-scale industrial boilers
45mm Radiant heating surfaces for medium- and large-scale industrial boilers
51mm High-pressure boiler components, such as reheaters and superheaters
60mm-76mm High-temperature and high-pressure main steam pipe systems
89mm-108mm Trunk pipelines in thermal power plants or large petrochemical facilities

2. Wall Thickness (WT)
Wall thickness is typically designed based on pressure rating and safety factor. Common wall thicknesses include:

2.5mm-5mm: Suitable for low-pressure steam or hot water boilers;

5mm-12mm: Mostly used for high-pressure heating piping, such as economizers and water walls;

≥12mm: Used in key areas of supercritical boiler systems.

3. Length
Boiler tubes are generally available in fixed or custom lengths. Common lengths include:

Custom lengths: 6m to 12m;

Custom lengths: 6m, 9m, and 12m;

Custom Processing: We can precisely cut or bend according to boiler design drawings.

III. Common Boiler Tube Materials
The material selection for boiler tubes directly impacts their heat resistance, pressure resistance, and corrosion resistance. The following are several common steel grades:

Material Grade Characteristics and Applications
20# Carbon structural steel, commonly used for heating surfaces in low- and medium-pressure boilers
20G Special boiler steel, with high strength and good ductility, is a common material in accordance with GB 5310
15CrMo and 12Cr1MoV alloy steel pipes, with excellent high-temperature resistance, are suitable for high-pressure boilers and superheaters
T22, T91, and T92 American Standard alloy steels, used in supercritical and ultra-supercritical power plant boiler systems

IV. Detailed Explanation of Common Boiler Tube Applications
Different parts of a boiler system have different requirements for steel tube dimensions and performance. The following is a classification of common applications:

1. Superheater Tubes Tubes

Operating temperatures reach over 540°C.

Requires high strength, oxidation resistance, and thermal fatigue resistance.

Commonly used alloy steels include 15CrMoG and T91.

Common sizes: OD 38mm and 51mm, wall thickness 4.5mm to 8mm.

2. Reheater Tubes

Used to heat high-pressure steam for recirculation.

Requires higher high-temperature corrosion resistance.

Similar size range to superheater tubes.

3. Water Wall Tubes

Used to absorb radiant heat around the boiler furnace.

Requires excellent material strength and formability.

Commonly used seamless carbon steel or low-alloy steel.

Common sizes: Φ32mm and Φ38mm.

4. Economizer Tubes

Installed at the tail end of the flue to recover waste heat from flue gas.

The temperature is relatively low.

Material: primarily carbon steel.

Common sizes: Φ38mm, Φ51mm, wall thickness 3.5mm-6mm.

5. Boiler Tubes and Convection Tube Bundles

Used in the heat transfer and evaporation sections of the boiler's mid-structure.

A variety of sizes are available, custom-made according to the design drawing.

V. Boiler Tube Selection Recommendations

When selecting boiler tubes, consider the following factors:

Design pressure and temperature requirements;

Corrosion and oxidation resistance;

Service life and economic efficiency;

Compliance with relevant standards, such as GB, ASTM, and DIN;

A requirement for seamless tube construction to minimize leakage risks.

VI. Extended Applications of Boiler Tubes
Besides boiler manufacturing, boiler tubes are also widely used in other thermal energy equipment and systems, such as:

Heat exchangers for oil refining equipment;

Heating systems for power plant auxiliary equipment;

Heat exchange systems for marine boilers and industrial furnaces;

City central heating systems.

VII. Summary
Boiler tubes play a vital role in modern industrial equipment. Whether in traditional energy systems or energy-efficient thermal projects, the appropriate boiler tube selection improves system efficiency, extends service life, and ensures operational safety. Understanding common sizes and applications will help you make more informed decisions during engineering design and procurement.

If you have boiler tube procurement needs, we recommend working with suppliers with professional production capabilities and certifications to ensure product quality meets national and international standards.

For further technical specifications, material comparison tables, or quotes, please contact BAOWI Steel's professional steel pipe service team for a one-stop solution.