New flow chart of double-sided submerged arc welding welded steel pipe

1. Panel inspection: After the steel plate used to manufacture the large-diameter submerged arc welded steel pipe enters the production line, the whole board ultrasonic inspection is first carried out. 2. Milling edge: double-sided milling of the two edges of the steel plate by the edge milling machine to meet the requirements Plate width, edge parallelism and groove shape; 3. Pre-bending: pre-bending the plate edge with a pre-bending machine to make the edge of the plate meet the required curvature; 4. Forming: first pre-bending on the JCO molding machine After half of the steel plate is pressed step by step, pressed into a "J" shape, and then the other half of the steel plate is also bent, pressed into a "C" shape, and finally formed an "O" shape of the opening. 5. Pre-welding: forming After the welded steel pipe joints and gas shielded welding (MAG) for continuous welding; 6. Internal welding: the use of longitudinal multi-wire submerged arc welding (up to four wire) welding inside the welded steel pipe; 7. External welding: The welding is carried out on the outer side of the welded submerged arc welded steel pipe by longitudinal multi-wire submerged arc welding; 8. Ultrasonic inspection I: 100% inspection of the inner and outer welds of the welded welded steel pipe and the base metal on both sides of the weld; 9. X-ray inspection I : 100% X-ray industrial TV inspection of internal and external welds, using image The system is to ensure the sensitivity of the flaw detection; 10. Expanding the diameter: expanding the diameter of the submerged arc welded steel pipe to increase the dimensional accuracy of the steel pipe and improving the distribution of stress in the steel pipe; 11. Hydraulic test: on the hydraulic testing machine The steel pipe after the diameter expansion is inspected one by one to ensure that the steel pipe meets the test pressure required by the standard. The machine has automatic recording and storage functions. 12. Chamfering: The steel pipe after passing the inspection is pipe end processed to meet the required pipe end. Groove size; process

Unwinding - Rolling - Leveling - Butt welding - Milling edge - Forming - Internal welding - External welding - Pipe cutting - Breaking - Subsequent welding - Hydraulic test

Inspection process

Raw Material Inspection - Leveling Inspection - Butt Welding Inspection - Forming Inspection - Internal Welding Inspection - External Welding Inspection - Pipe Cutting Inspection - Ultrasonic Inspection - Groove Inspection - Dimensional Inspection - X-ray Inspection - Hydraulic test - final inspection


· Domestic anti-corrosion materials generally use cement mortar, and some use non-toxic epoxy paint (thickness 0.4mm).

· Domestic and international anti-corrosion coating EDM test voltage is generally 3000 volts, the maximum is not more than 5000 volts, and the technical content is high 10 kV.

Field solderability

The weldability of the site is mainly determined by the material of the steel pipe and the dimensional tolerance of the port.

Considering the requirements for the installation and construction of steel pipes, the consistency of the steel pipe processing and the consistency of the geometrical dimensions are particularly important.

Spiral welded pipe production is a continuous continuous process that is basically stable under the same working conditions: the straight seam welded pipe production process is segmented, including whole plate / indenter / preroll / spot welding / welding / finishing / group pairing Multiple process steps. This is an important feature of spiral welded pipe production that is different from the production of straight welded pipe.

Stable production conditions are very convenient for welding quality control and geometric size assurance. Due to the regularity of the spiral welded pipe and the even distribution of the weld, the spiral steel pipe has a very good ellipticity and end face perpendicularity with respect to the straight welded pipe, which ensures the accuracy of the pair alignment of the on-site steel pipe welding group.

·The effect on the flow characteristics of the transport medium

The pressure drop in the transfer line is proportional to the length of the tube, the fluid viscosity coefficient, the fluid velocity, and the fluid drag coefficient, and inversely proportional to the inner diameter of the tube. The fluid drag coefficient is related to both the Reynolds number and the roughness of the inner wall surface of the tube. It has been determined that the roughness of the inner wall surface of the pipe has an effect ten times greater than that of the local raised surface (such as a spiral weld or a longitudinal weld or even an inner annular weld).


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