September 9, 2026
ERW (Electric Resistance Welded) steel pipes are made by cold-forming a flat steel coil into a cylindrical shape and fusing the seam using high-frequency electric current — with no filler metal. The entire process runs as one continuous line, from raw coil to finished, tested pipe.
For contractors, fabricators, and distributors across Haryana and North India sourcing pipe in bulk, knowing exactly how this process works makes it much easier to judge pipe quality and spot a well-made batch from a poorly finished one.
Production starts with a steel coil chosen to meet a specific chemical composition and mechanical strength range. The coil is loaded onto an uncoiler and leveled to remove residual stress and shape deviation — poor coil quality at this stage directly weakens the final weld.
The coil is slit to the precise strip width required for the target pipe diameter. Slitting blades and milling edges trim the strip’s edges clean, since even minor edge defects can cause weld flaws later in the process.
The flat steel strip is fed through a series of forming rollers that gradually bend it — first into a curved shape, then progressively tighter — until the two edges meet to form a cylinder (or square, rectangle, or oval, depending on the profile being produced).
This is the step that gives ERW pipe its name. High-frequency electric current passes through the two edges of the strip. Thanks to the skin and proximity effect, the edges heat rapidly to around 1,200°C and are pressed together under force, fusing into a solid, seamless-looking weld — no filler wire or rod involved.
Right after welding, the excess metal squeezed out of the joint (the internal and external “bead”) is trimmed off using scarfing tools, giving the pipe a clean, smooth surface. The pipe then passes through sizing rolls that correct the outer diameter and roundness, ensuring uniform wall thickness along its length.
For pipes going into pressure applications or where the standard demands it, the weld zone is normalized or stress-relieved. This step improves the microstructure around the weld and reduces residual stress, making the pipe more reliable under load.
Before the pipe is ready to ship, it goes through dimensional checks (outer diameter, wall thickness, length), weld inspection, and mechanical testing such as tensile and impact tests. Only after passing these checks is the pipe cut to length, bundled, and packed.
Steel Star, under Karauli Steel, runs its production out of the HSIIDC Industrial Estate in Kundli, Sonepat, Haryana — manufacturing round, square, rectangular, and oval steel tubes and pipes with checks built into every stage of the process described above. That location keeps delivery times short for contractors and distributors across Delhi NCR, Haryana, and the wider North India market.
Before placing a bulk order, it’s worth checking the full product size and thickness charts and the quality standards each batch is tested against, or reading more about round pipe standards if you’re deciding between profiles.
ERW uses high-frequency electric current to heat and fuse the pipe’s edges, with no filler metal — unlike methods that add weld wire or rod to join the seam.
Not always — it depends on the application. Pressure-rated and structural pipes are often normalized or stress-relieved to strengthen the weld zone; general-purpose pipe may not need this step.
Manufacturers typically run dimensional checks, weld inspection, and mechanical tests like tensile and impact testing before the pipe is cut and packed.
Yes. The same coil-to-tube process produces square, rectangular, and oval profiles, not just round pipe — the forming rollers are simply set up differently
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Steel Star by Karauli Steel
📞 +91 93111-11154
📍 148, HSIIDC PHASE-II, Industrial Estate, Kundli, Sector-53 Sersa, Sonepat, Haryana
