Electric resistance welded line pipe to API 5L PSL1 and PSL2, grades B to X70. Cost-effective thin-wall option for low to medium pressure lines from NPS 1/2 inch to 24 inch.
- Standard: API 5L, ISO 3183, ASTM A53, ASME B36.10
- Grades: Grade B, X42, X46, X52, X56, X60, X65, X70
Specifications
| Outer diameter | 1/2" - 24" (12.7 - 610 mm) |
|---|---|
| Wall thickness | SCH 10 - SCH 80, or 2.0 - 25.4 mm |
| Schedule | SCH 10, 20, 40, 80, or custom |
| Length | 6 m, 12 m, 20 FT, 40 FT, or custom 5 - 18 m |
| Ends | Plain, beveled, threaded |
| Surface treatment | Black painting, varnish, 3PE/3LPE, FBE, galvanized |
| Manufacturing process | Electric resistance welding (high frequency) |
| Pressure rating | Low to medium pressure service |
How ERW Pipe Is Made
ERW stands for electric resistance welding. A steel coil is unrolled, formed into a cylindrical shape through a series of rollers, and the two edges are pressed together while a high frequency alternating current is passed through them. The resistance at the faying surfaces generates enough heat to bring the steel to welding temperature, and the pressure roll forges the edges into a solid, forged weld. No filler metal is used. The external weld flash is then scarfed off, and the internal flash is either left in place or removed depending on the specification. Because the process starts from coil, ERW pipe is produced continuously at high speed, which is why it is significantly cheaper per ton than seamless pipe in the same size range.
When to Choose ERW Instead of Seamless
ERW pipe is the economical choice for low to medium pressure service in sizes up to 24 inch where the wall thickness is relatively thin. It is widely used for water lines, gathering lines, structural and piling work, and fire protection systems. The limitation is the weld seam: it is the area most vulnerable to preferential corrosion and to failure under cyclic loading, which is why ERW pipe is generally not accepted for high pressure transmission lines, sour service, or critical offshore applications. As a rule of thumb, if the wall thickness exceeds about 12 mm, or if the line will operate above roughly 60 percent of the specified minimum yield strength, seamless or LSAW pipe is the safer choice.
Is ERW pipe as strong as seamless pipe?
For the same grade and wall thickness, ERW and seamless pipe have the same specified minimum yield and tensile strength, so the base material strength is equal. The difference is the weld seam. An ERW seam is a forged weld that in well-controlled production achieves full parent-metal strength, but it remains a discontinuity. This is why standards restrict ERW pipe for certain critical services and why full-length seam inspection is mandatory. For water, gathering and structural service the difference is not significant; for high pressure or sour service it is.
What does the ERW pipe price difference look like compared with seamless?
As a general market indication, ERW pipe is typically 5 to 15 percent cheaper per ton than seamless pipe in the same grade and comparable wall thickness, with the gap widening for thin-wall sizes and narrowing as wall thickness increases. The actual differential moves with coil and billet prices, so a current quotation should always be requested for a specific specification.
Materials
- Carbon steel
Typical applications
- Low and medium pressure water lines
- Oil and gas gathering lines
- Structural and piling applications
- Fence posts and scaffolding
- Fire protection piping
Inspection & testing
- Eddy current testing of the weld seam (full length)
- Ultrasonic testing of weld seam
- Hydrostatic pressure test
- Flattening and bend test
- Chemical and mechanical testing
- Third-party inspection (SGS, BV, TUV)
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