Hot New Products Welded Steel Pipe - Large Diameter Heavy Wall Welded Steel Pipe – Haihui

Thick-walled steel mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction. For the transport of liquids: water supply and drainage. For gas transportation: gas, steam, liquefied petroleum gas. For structural purposes: as piling pipe for bridges; docks, roads, buildings and other structures tube.

The key of quality for thick wall steel pipe should be thickness uniformity, thick-walled steel pipe wall thickness is not controlled directly affect the quality and usefulness of steel pipe, thick wall steel pipe, large diameter seamless steel pipe for general use in a variety of machining, thick wall parts processing, uniform wall thick-walled steel pipe will directly affect the quality of post-processed parts, thick-walled steel pipe wall is not controlled, the overall quality of steel is not strictly.

Size: OD :351-1050mm, thickness :8-30mm.

Material: 20 #, 16Mn, Q235B, Q345B, X42, X52, X70, alloy steel, stainless steel.

Standard: GB/T3091-2001, GB/T 3092-1993, GB/T 9711.1-1997, GB/T9711.2, GB/T9711.3t etc.

1. Plate detection: after the steel plate used to manufacture large-diameter submerged arc welded straight seam steel pipe enters the production line, first conduct full plate ultrasonic inspection;

2. Edge milling: the two edges of the steel plate are milled on both sides by the edge milling machine to achieve the required plate width, plate edge parallelism and groove shape;

3. Pre bending: use the pre bending machine to pre bend the plate edge, so that the plate edge has the required curvature;

4. Forming: on the JCO forming machine, first press half of the pre bent steel plate into a “J” shape through multiple step stamping, then bend the other half of the steel plate into a “C” shape, and finally form an open “O” shape

5. Pre welding: make the formed straight seam welded steel pipe joint and use gas shielded welding (MAG) for continuous welding;

6. Internal welding: longitudinal multi wire submerged arc welding (up to four wires) is used to weld inside the straight seam steel pipe;

7. External welding: longitudinal multi wire submerged arc welding is used to weld the outside of the longitudinal submerged arc welded steel pipe;

8. Ultrasonic inspection I: 100% of the internal and external welds of the straight welded steel pipe and the base metal on both sides of the weld;

9. X-ray inspection I: 100% X-ray industrial television inspection shall be carried out for internal and external welds, and image processing system shall be adopted to ensure the sensitivity of flaw detection;

10. Diameter expansion: expand the full length of submerged arc welded straight seam steel pipe to improve the dimensional accuracy of steel pipe and improve the distribution of internal stress in steel pipe;

11. Hydrostatic test: inspect the expanded steel pipes one by one on the hydrostatic test machine to ensure that the steel pipes meet the test pressure required by the standard. The machine has the function of automatic recording and storage;

12. Chamfering: process the pipe end of the qualified steel pipe to meet the required groove size of the pipe end;

13. Ultrasonic inspection II: carry out ultrasonic inspection one by one again to check the possible defects of longitudinal welded steel pipes after diameter expansion and water pressure;

14. X-ray inspection II: X-ray industrial television inspection and pipe end weld photography shall be carried out for steel pipes after diameter expansion and hydrostatic test;

15. Magnetic particle inspection of pipe end: conduct this inspection to find pipe end defects;

16. Corrosion prevention and coating: the qualified steel pipe shall be subject to corrosion prevention and coating according to the user’s requirements.