ERW Steel Pipe Oil casing pipes: 1)Nominal OD: 219.1-609.6mm(8 5/8''-24) 2)Wall thickness: 6-19.1mm 3)Standard: API SPEC 5CT Electric Resistance Welded (ERW) and High Frequency Induction (HFI) Welded Pipe Originally this type of pipe, which contains a solid phase butt weld, was produced using resistance heating to make the longitudinal weld (ERW), but most pipe mills now use high frequency induction heating (HFI) for better control and consistency. However, the product is still often referred to as ERW pipe, even though the weld may have been produced by the HFI process. ERW steel pipes are widely used in low pressure liquid delivery such as water, gas, air, oil and steam and for machine structural purposes.
