Initially, such pipes containing solid relative welds were produced using resistance heating for longitudinal welds (ERW), but most pipe fabrication plants now use high-frequency induction heating (HFI) for better control and consistency. However, the product is still often referred to as an ERW tube, even though the weld may have been produced by the HFI process.

Defects that may occur in ERW/HFI pipes are related to strip production, such as defects at lamination and narrow welds. Non-fusion due to insufficient heat and pressure is the main defect, although hook cracks can also form due to the rearrangement of non-metallic inclusions at the welding interface. Because the weld is not visible after the trimming, and because of the nature of the solid phase welding process, if the welding parameters exceed the set limits, it is possible to produce a fairly long weld with poor fusion. In addition, early ERW pipes are prone to pressure reversals, a problem that can cause use failures at lower stresses than those seen in pre-use pressure tests. The problem was caused by crack growth during pressure test hold, which in the case of earlier ERW tubes was due to a combination of low weld toughness and lack of fusion defects.

Notes on non-fusion of ERW welds
Because of these early problems, ERW tubes are often viewed as secondary tubes only suitable for low-pressure applications. However, due to the shortage of seamless tubes and the lower cost of ERW tubes, suppliers and end users in the 1980s greatly improved the quality of pipe plants. In particular, automated ultrasonic inspection equipment is crucial for accurate tracking of welds, which may rotate slightly when the pipe leaves the welding station. In addition, weld heat treatment standards are essential to ensure good toughness, and some specifications require local weld heat treatment with induction coils followed by an integral normalizing treatment of the entire pipe. The stove. As a result of these improvements, modern ERW/HFI pipelines have better performance than traditional products and have been accepted by many high-pressure gas delivery operators.