... 2 Standards ERW Tube Mill(219mm-630mm)High-grade, large caliber and high frequency straight seam welded pipes are widely ... and equipment manufacturers .In recent years,with learning & developing large caliber ERW production lines (Φ219mm –Φ2540mm )with our own intellectual ... ,have been patented in China . We have finished designing large caliber ERW production lines specifications:16” ERW, 20” ERW, 24 ...