Both internal and external welding of spiral steel pipes for 3PE anti-corrosion steel pipes are carried out using single wire or double wire submerged arc welding to obtain stable welding specifications. The welded seams are all inspected by an online continuous ultrasonic automatic damage detector, ensuring the coverage of non-destructive testing for spiral steel pipes. The parts with continuous ultrasonic testing marks on the welds of spiral steel pipes used for 3PE anti-corrosion steel pipes have undergone manual ultrasonic and X-ray re examination