ERW Steel Pipe, which is Electrical Resistance Welding Steel Pipe, is manufactured using steel coils: the coil is first uncoiled, then smoothed, cut and, finally formed into a pipe shape by joining its two extremities electrically.
ERW Steel Pipes are available in sizes between 1/2 and 24 inches, in carbon steel (ASTM A53 is the most common specification) and stainless steel (ASTM A312). In terms of dimensions, the ASME B36.10 and ASME B36.19 are the key reference specifications (API 5L for welded ERW line pipes).
In the initial times, it was done with the low-frequency A.C. current to heat the edges. Now, since 1970 the low-frequency process changed to high-frequency A.C. current to produce a higher quality weld. In the last few years, ERW pipes are have become an efficient alternative to seamless pipes, both in terms of price and performance, due to the modern welding technologies adopted by ERW pipe manufacturers (example HFW, high-frequency welding). These advancements in welding technologies have reduced, over time, the technical superiority of seamless pipes vs ERW pipes, making them interchangeable at least in some applications (low/medium pressure and temperature). Of course, seamless pipes will always benefit from the intrinsic superior mechanical strength of steel billets vs. coils and plates.
ERW pipes are extensively used in agriculture, industry and construction activities like scaffolding and casing in bore wells. They are used for conveying water, gas, crude oil and chemicals at various pressures and densities over long distances. Considering the challenging and varied applications, the pipes are produced to meet very high standards of both national and international specifications.
Here are some normal specifications used for ERW Steel Pipe as below.
- API SPEC 5L — Specification for Line Pipe
- API SPEC 5CT — Specification for Casing and Tubing
- ASTM A53/A53M — Standard Speciﬁcation for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless
- ASTM A252 — Standard Speciﬁcation for Welded and Seamless Steel Pipe Pile
- ASTM A500 — Standard Speciﬁcation for Cold-Formed Welded and Seamless Carbon Steel Structural Tubing in Rounds and Shapes
- ASTM A795 — Standard Speciﬁcation for Black and Hot-Dipped Zinc-Coated (Galvanized) Welded and Seamless Steel Pipe for Fire Protection Use
- ASTM A135 — Standard Speciﬁcation for Electric-Resistance-Welded Steel Pipe
- BS 1387 — Specification for screwed and socketed steel tubes and tubulars and for plain end steel tubes suitable for welding or for screwing to BS 21 pipe threads
- BS 1139 — Metal scaffolding. Specification for prefabricated mobile access and working towers
- EN 39 — Loose steel tubes for tube and coupler scaffolds
- EN 10217 — Welded steel tubes for pressure purposes. Technical delivery conditions. Non-alloy steel tubes with specified room temperature properties
- EN 10219 — Cold formed welded structural hollow sections of non-alloy and fine grain steels
- EN 10255 — Non-alloy steel tubes suitable for welding and threading.
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