SML AND ERW PIPE & TUBES
SML (Seamless) and ERW (Electric Resistance Welded) pipes and tubes are two commonly used types of steel pipes, each with distinct manufacturing processes and applications. Seamless (SML) pipes are produced without a weld seam by heating a solid steel billet and then extruding or drawing it into a pipe shape. This results in a pipe that is uniform in structure and strength throughout, making it ideal for high-pressure applications in industries such as oil and gas, power generation, and chemical processing. In contrast, ERW pipes are made by cold-forming a flat steel strip into a cylindrical shape and then welding the seam using electric resistance welding.
Specifications
| Specification |
SML (Seamless) Pipe |
ERW (Electric Resistance Welded) Pipe |
| Manufacturing Process |
Hot extrusion or rotary piercing |
Cold-forming followed by electric resistance welding |
| Weld Seam |
No weld seam (monolithic structure) |
Has a longitudinal weld seam |
| Surface Finish |
Generally rougher due to hot forming |
Smoother due to cold-forming |
| Strength |
Higher strength, uniform throughout |
Slightly lower strength at the weld area |
| Pressure Tolerance |
High-pressure applications |
Suitable for low to medium-pressure applications |
| Size Range |
Typically smaller diameters (up to 20 inches) |
Can be produced in larger diameters |
| Wall Thickness Tolerance |
Less uniform; depends on the process |
Very uniform due to controlled forming |
| Cost |
More expensive |
More economical |
| Common Standards |
ASTM A106, A53 Grade B, API 5L |
ASTM A53, A500, API 5L |
| Applications |
Oil & gas, chemical processing, power plants |
Water lines, scaffolding, structural uses |
Size and Weight Chart
| Nominal Pipe Size (NPS) |
Outer Diameter (OD, mm) |
Wall Thickness (mm) |
Weight (kg/m) |
| 1/2" |
21.3 |
2.77 (Sch 40) |
1.27 |
| 3/4" |
26.7 |
2.87 (Sch 40) |
1.68 |
| 1" |
33.4 |
3.38 (Sch 40) |
2.44 |
| 1 1/2" |
48.3 |
3.68 (Sch 40) |
4.39 |
| 2" |
60.3 |
3.91 (Sch 40) |
5.44 |
| 3" |
88.9 |
5.49 (Sch 40) |
10.29 |
| 4" |
114.3 |
6.02 (Sch 40) |
14.98 |
| 6" |
168.3 |
7.11 (Sch 40) |
28.26 |
| 8" |
219.1 |
8.18 (Sch 40) |
42.55 |
| 10" |
273.0 |
9.27 (Sch 40) |
61.62 |
| 12" |
323.8 |
9.53 (Sch 40) |
76.46 |
