How to choose the right small-diameter seamless steel pipe?

Selecting the right small-diameter seamless steel pipe requires considering factors such as operating environment, pressure level, temperature, corrosion resistance, structural requirements, and industry-specific standards. Below is a practical guide to choosing the appropriate specification based on different application scenarios.

How to Choose the Right Small-Diameter Seamless Steel Pipe?

Hydraulic Systems
For hydraulic circuits and high-pressure fluid transmission, DIN 2391 St52 / EN 10305-1 E355 seamless tubes in Φ10–Φ50 mm with 1.5–4 mm wall thickness are recommended. These tubes provide high strength, excellent dimensional accuracy, and stable surface protection such as phosphating or galvanizing to prevent corrosion.

Food Machinery / Medical Equipment
For hygienic, corrosion-resistant applications, 304 / 316L stainless steel seamless tubes in Φ6–Φ38 mm with 1–2 mm wall thickness are ideal. They offer superior corrosion resistance, polishability, and full compliance with food-grade and medical sanitation requirements.

High-Temperature Conveying
For systems handling hot fluids or steam, ASTM A106 Grade B/C seamless steel pipes in Φ20–Φ89 mm and 3–6 mm wall thickness are suitable. These grades deliver stable performance under elevated temperatures and maintain excellent strength at high thermal loads.

Precision Instruments
For instrumentation, control devices, and fine-mechanical assemblies, ultra-thin wall precision tubes in Φ3–Φ20 mm, with wall thickness as low as 0.5 mm, are recommended. Their high dimensional accuracy and uniformity make them ideal for precision-critical applications.

Industrial Structural Components
For general structural use, Q345 or 20# carbon steel seamless pipes in Φ20–Φ89 mm offer a balance of high strength, good weldability, and competitive cost, making them suitable for brackets, frames, and mechanical structures.