Every pipe at Gazelle Tube passes through thirteen instrumented stages. Welding current, sizing pressure, eddy current signal and straightening parameters are logged continuously against heat number — full traceability, by design.
Why electric resistance welding.
ERW pipe is formed from a single steel strip and welded longitudinally with high-frequency current — no filler material, no porosity, and tighter dimensional control than seamless for the size range used in firefighting, water and structural piping.
| Aspect | ERW (our process) | Seamless |
|---|---|---|
| Formation | Strip rolled into tube, edges welded by HF current | Solid billet pierced and elongated |
| Dimensional control | Tight OD and wall tolerance from sizing rolls | Greater wall variation across the section |
| Best fit | Firefighting, water, gas, structural, HVAC ½″–12″ | High-pressure / high-temperature process service |
| Inspection | 100% in-line eddy current + hydrostatic | Sample-based NDT; longer cycle time |
| Cost & lead time | Faster production, lower cost per meter | Slower, higher cost — reserved for severe service |
Thirteen stages, one heat number.
Each stage is monitored, logged and reconcilable to the source coil. Engineering notes call out the parameters that drive dimensional control and weld integrity.
Uncoiling
Steel coil mounted on the decoiler and fed onto the line at controlled tension.
Coil ID & heat number loggedLeveling
Strip passed through leveling rolls to remove coil set and produce a flat, stable feedstock.
Critical for OD toleranceSlitting
Master coil slit longitudinally to the precise strip width required for the target pipe diameter.
Width tolerance ±0.2 mmRecoiling
Slit strip recoiled and staged for the forming line, edge-protected and labeled by master coil.
Edge condition preservedUncoiling to line
Slit coil mounted at the head of the forming line and end-welded to the previous coil for continuous production.
Continuous run, no stopsRoll & cage forming
Strip progressively shaped through forming and cage rolls into a cylindrical open-seam tube.
Sets pipe geometryElectric resistance welding
High-frequency current heats the strip edges; squeeze rolls forge them into a solid, full-penetration seam.
Solid-state weld, no fillerWeld seam removal
Outer and inner weld flash trimmed flush with the pipe surface for a clean profile.
ID & OD scarfingEddy current
100% in-line eddy current test detects surface and near-surface defects in the weld zone.
Continuous NDTSizing
Pipe passed through sizing rolls to bring outside diameter into final tolerance.
OD calibrated to specFlying cutting
Cold saw on a moving carriage cuts the continuous pipe into precise lengths without stopping the line.
Length ±2 mmStraightening
Multi-roll straightener removes residual bow and twist, delivering a true, straight pipe.
Bow tolerance verifiedBundling
Pipes inspected, end-finished, marked with heat number, then hex-bundled and strapped for shipment.
Heat number on every lengthTested where it matters.
Inspection is built into the process line, not bolted on at the end. Every parameter is logged and reconcilable to mill test certificate.
Hydrostatic
Pressure-tested to a minimum of 2.5 × design working pressure per ASTM A53.
Ultrasonic
100% weld seam inspection by ultrasonic phased-array probe.
Eddy current
Continuous online detection of surface and near-surface defects.
Mechanical
Tensile, flattening, bending and expanding tests per heat number with retained samples.
See it in person.
Consultants and clients are welcome to walk the production floor and review test records with our quality team.