Welded steel pipes must undergo mechanical performance tests, flattening tests, and flare tests to ensure they meet the standards. These pipes should be capable of withstanding a certain internal pressure, and if required, a pressure test of 2.5 MPa should be conducted for one minute without any leakage. In some cases, hydrostatic testing can be replaced by eddy current testing, as specified in GB 7735, "Eddy Current Testing Method for Steel Tubes." The process involves placing the probe on a frame, maintaining a distance of 3–5 mm between the flaw detection sensor and the weld seam. As the pipe moves rapidly, the entire weld is scanned, and the detected signals are automatically processed and sorted by the eddy current flaw detector, ensuring accurate results.
After flaw detection, the welded pipe is cut to the required length using a flying saw and then removed from the frame via a flipping mechanism. Both ends of the steel pipe are chamfered, marked, and finally packaged in hexagonal packaging before being shipped.
Processing Methods
The primary processing methods for straight-seam steel pipes include:
Forging: This method uses the impact of a forging hammer or the pressure from a press to shape the billet into the desired form and size. It is commonly used for producing strong and durable steel components.
Extrusion: A technique where metal is placed inside a sealed extrusion chamber and forced through a die to create a specific shape. This method is often used for non-ferrous metals and produces consistent cross-sectional profiles.
Rolling: In this process, the metal billet is passed through rotating rolls with a gap of various shapes. The rolling action compresses the material, reducing its cross-section while increasing its length.
Drawing: This involves pulling the rolled metal blank through a die to reduce its cross-sectional area and achieve the desired dimensions. It is often used in cold working processes to improve surface finish and dimensional accuracy.
Cold Processing: This refers to forming or shaping steel at room temperature, which helps maintain the material’s strength and hardness while achieving precise dimensions.
These methods are essential in manufacturing high-quality steel pipes that meet industry standards and are suitable for a wide range of applications, from construction to industrial piping systems.
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