Seamless steel pipes with small outer diameters are called small-diameter seamless steel pipes. Small-diameter seamless steel pipes can be further divided into: seamless small-diameter steel pipes and straight-seam (also called welded) small-diameter seamless steel pipes. Generally, pipes with an outer diameter of 4mm or less than 89mm can be collectively referred to as small-diameter seamless steel pipes. However, many people don't know much about them.
Standard Specifications of Seamless Steel Pipes— Common Sizes
Diameter (OD) and Wall Thickness (WT)
Small-diameter seamless steel pipes generally range from 4 mm to 89 mm in outer diameter.
Common industrial and hydraulic applications often use Φ6 mm to Φ89 mm.
Wall thickness usually ranges from 1.0 mm to 5.0 mm, but precision tubes may have wall thicknesses as low as 0.5 mm.
For high-strength or thick-walled applications, wall thickness may go up to 10 mm.
Small-diameter seamless pipes are typically manufactured using cold drawing or cold rolling processes, ensuring high dimensional accuracy, smooth surfaces, and tight tolerance control.
Specifications of Small Diameter Seamless Steel Pipes
| Specification | Specification | Specification |
| 6*1 | 18*5 | 25*6 |
| 8*1 | 18*6 | 25*7 |
| 8*1.5 | 19*1.5 | 25*8 |
| 8*2 | 19*2 | 27*2 |
| 10*1 | 19*2.5 | 27*2.5 |
| 10*1.5 | 19*3 | 27*3 |
| 10*2 | 19*4 | 27*4 |
| 10*2.5 | 19*5 | 27*5 |
| 12*1 | 20*1.5 | 27*6 |
| 12*1.5 | 20*2 | 27*7 |
| 12*2 | 20*2.5 | 28*2 |
| 12*2.5 | 20*3 | 28*2.5 |
| 12*3 | 20*4 | 28*3 |
| 14*1.5 | 20*5 | 28*3.5 |
| 14*2 | 20*6 | 28*4 |
| 14*2.5 | 22*1.5 | 28*5 |
| 14*3 | 22*2 | 28*6 |
| 14*4 | 22*2.5 | 28*7 |
| 16*1.5 | 22*3 | 30*2 |
| 16*2 | 22*4 | 30*3 |
| 16*2.5 | 22*5 | 30*4 |
| 16*3 | 22*6 | 30*5 |
| 16*4 | 25*1.5 | 30*6 |
| 16*5 | 25*2 | 30*7 |
| 18*1.5 | 25*2.5 | 30*8 |
| 18*2 | 25*3 | 41*2 |
| 18*2.5 | 25*3.5 | |
| 18*3 | 25*4 | |
| 18*4 | 25*5 |
Small-diameter seamless steel pipes are manufactured and tested according to standards like ASTM A106, ASTM A53, EN 10216, and GB/T 8163, which specify their chemical composition, mechanical properties, and dimensional tolerances.For any questions, please feel free to contact us via email: pipe@stpipefitting.cn.
