Sharing China-Made with Global Customers
Sharing China-Made with Global Customers
Longitudinal welded pipes are widely used in many fields. Let's explore the process of how these pipes are manufactured:
Steel Plate Inspection:
Initially, the entire steel plate undergoes an ultrasonic inspection to ensure the straightness of the submerged arc welding joints on large-diameter pipes.
Edge Milling:
A milling machine performs double-sided milling on the edges of the steel plate to meet the required plate width, edge parallelism, and groove shape.
Edge Pre-bending:
The edges of the steel plate are pre-bent using a pre-bending machine to achieve the necessary curvature.
Forming:
On a JCO forming machine, the steel plate is progressively pressed into a "J" shape, then further into a "C" shape, and finally into an open "O" shape.
Pre-welding:
The longitudinal welded pipe is prepared using gas welding (MAG) for continuous welding.
Internal Welding:
Longitudinal multi-wire submerged arc welding (up to four wires) is used to weld the internal seam of the pipe.
External Welding:
The external seam of the pipe is welded using longitudinal multi-wire submerged arc welding.
Ultrasonic Inspection I:
A 100% ultrasonic inspection is conducted on the internal and external welds and the adjacent metal to detect any defects.
X-ray Inspection I:
A 100% X-ray industrial television inspection is performed on the internal and external welds. The image data processing system ensures the sensitivity of the inspection.
Diameter Expansion:
The entire length of the submerged arc welded pipe is expanded to improve dimensional accuracy and stress distribution within the pipe.
Hydrostatic Testing:
Each expanded pipe undergoes a hydrostatic test on a hydraulic testing machine to ensure it meets the standard test pressure. This machine has automatic recording and storage capabilities.
Beveling:
The inspected longitudinal welded pipes are beveled at their ends to meet the required groove dimensions for pipe ends.
Ultrasonic Inspection II:
A second ultrasonic inspection is carried out to detect any defects that may have emerged after diameter expansion and hydrostatic testing.
X-ray Inspection II:
Another X-ray industrial inspection is performed, focusing on the weld seams at the pipe ends after diameter expansion and hydrostatic testing.
Magnetic Particle Inspection:
The ends of the longitudinal welded pipes are subjected to magnetic particle inspection to identify any end defects.
This structured and rigorous manufacturing process ensures that longitudinal welded pipes meet stringent quality standards, making them suitable for a wide range of applications.
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