Welded pipe production line

The welded steel tube production line, also known as the straight seam welded pipe production line, refers to the material (same or different) of the workpiece to be welded. A process in which the materials of a workpiece are bonded atomically to form a permanent connection by applying heat or pressure or both, with or without filler material.

The pipes obtained by straight seam welding on welding equipment are called straight seam welded pipes (such as ERW pipes and LSAW pipes). The straight seam welded pipe gets its name because the welded part of the steel pipe is in a straight line. Among them, according to different purposes, there are different subsequent production processes. It can be roughly divided into scaffolding tubes, fluid tubes, wire casings, bracket tubes, guardrail tubes, etc. Low-pressure fluid welded pipe is a kind of straight seam welded pipe, which is generally used for the transportation of water and gas. After welding, one more hydraulic test is performed than ordinary welded pipe. The current low-pressure fluid pipe is a little higher than ordinary straight seam welded pipe.

Description of the main production process of large diameter longitudinal welded pipe:

1. Plate inspection: After the steel plate used to manufacture large-diameter submerged arc welded straight seam steel pipes enters the production line, the entire plate is firstly inspected by ultrasonic;

2. Edge milling: Double-sided milling is performed on both edges of the steel plate by the edge milling machine to achieve the required plate width, plate edge parallelism and groove shape;

3. Pre-bending: Use a pre-bending machine to pre-bend the edge of the plate so that the edge of the plate has a curvature that meets the requirements;

4. Forming: On the JCO forming machine, half of the pre-bent steel plate is first pressed into a "J" shape through multiple step-by-step stamping. Then bend the other half of the steel plate in the same way, press it into a "C" shape, and finally form an open "O" shape

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

6. Internal welding: use tandem multi-wire submerged arc welding (up to four wires) to weld on the inside of the straight seam steel pipe;

7. External welding: use tandem multi-wire submerged arc welding to weld on the outside of the straight seam submerged arc welded steel pipe;

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

9. X-ray inspection Ⅰ: 100% X-ray industrial TV inspection for internal and external welds, using image processing system to ensure the sensitivity of flaw detection;

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

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

12. Chamfering: process the pipe end of the qualified steel pipe to reach the required pipe end bevel size;

13. Ultrasonic inspection Ⅱ: Conduct ultrasonic inspection one by one again to check possible defects of straight seam welded steel pipes after diameter expansion and hydraulic pressure;

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