Boiler Tube Size Chart in mm

Boiler tubes come in a wide range of sizes, with commonly used outer diameters (OD) ranging from 12.7mm to 127mm and inner diameters (ID) from 6.35mm to 152.4mm. In practical applications, the outer and inner diameters should be selected appropriately based on the actual pressure and temperature requirements of the boiler.

Boiler Tube Size Chart in mm

Boiler Tube Diameter Range

1. Small Diameter

Small diameters are typically found in sizes such as φ18×3mm and φ22×4mm. These smaller diameter boiler tubes are commonly used in boiler systems with limited space or relatively low medium flow requirements, adapting well to specific installation spaces and operating conditions.

2. Medium Diameter

Common medium diameter sizes include φ38×4.5mm and φ42×5mm. These sizes are widely used in industrial boilers, meeting the operational needs of most conventional boilers, ensuring sufficient strength and stability while also facilitating heat transfer and medium flow.

3. Large Diameter

Large diameter boiler tubes include sizes such as φ60×6mm and φ76×8mm. These large diameter tubes are primarily used in large industrial boilers or boiler equipment with special requirements to meet greater medium flow and higher pressure demands.

For example, in some power generation boilers or large heating boilers, larger diameter boiler tubes are required to ensure the efficient operation of the entire boiler system.

4. Special Types

In addition, there are some special-purpose boiler steel tube specifications, such as high-temperature resistant stainless steel boiler tubes. These may have specifications such as φ32×3.5mm (304 stainless steel) and φ48×5.5mm (316 stainless steel) to adapt to boilers operating in high-temperature environments, ensuring the safe and stable operation of the boiler.

Relationship between Boiler Tube Wall Thickness and Pressure

Actual wall thickness should be calculated according to the following standards: ASME Boiler Code, EN 10216, GB/T 5310, ASTM A192 / A210 / A213.

FAQ

1. What are the most commonly used boiler tube sizes?

The most common sizes in industrial boilers are:

OD 38 mm

OD 42 mm

OD 51 mm

Among them, φ38 × 4.5 mm is the most widely used.

2. What is the minimum wall thickness for high-pressure boiler tubes?

There is no uniform minimum value; it must be calculated using a formula. However, in engineering practice, it is generally:

High-pressure boilers ≥ 4 mm;

Ultra-high-pressure boilers ≥ 6–8 mm.

Summary

Boiler tube sizes cover a wide range, but the core of correct selection is not the size itself, but rather the matching of pressure, temperature, and standards. In industrial boilers and power plant boilers, small and medium diameter seamless boiler tubes are still the mainstream, while high-parameter units rely more on thick-walled alloy steel or stainless steel tubes.