Submerged Arc welding with filler metal: welding is performed inside and outside the tube with 100% ultrasound control of the welding wire. Each tube is hydraulically tested.
Welding is performed without metal filler by melting both edges of the coil in order to allow them to mix after passing through a mould calibrated to the external diameter of the tube. This operation is also performed under 100% ultrasound control and each tube is hydraulically tested.
Welding wire: 100% ultrasound + 250 mm X-rayed on each side