Pipe Making
The spiral forming process uses hot rolled steel coil as raw material. The steel uncoiled, leveled passed through a forming station that spirals the steel to the required outside diameter. The spiral seam is then welded both internally and externally by the “submerged arc weld” (SAW) process as part of the forming operation.
The pipe shell thus formed is cut to the required length as it travels out of the forming and welding machine. Spiral welded steel pipes are characterized by its continuous welded helical seam from end to end, which also gives it additional stiffness.
The material passes through all these production stages continuously. The angle between the flat strip being fed into the machine and the finished pipe leaving the machine controls the pipe diameter through the ratio of strip width to the angle of the weld in the pipe.
Because of the method of manufacture, a wide variety of diameters can be produced. The diameter tolerance is small, particularly with regard to ovality; and the pipe, due to its symmetry, has inherent straightness. The length range is infinite and is controlled only by the economics of transportation.
Generally, the spiral welded pipe unit adopts the online continuous inspection method to ensure the welding quality of the weld. This is another important feature that distinguishes the spiral welded pipe production from the straight seam welded pipe production. Continuous inspection is beneficial to the monitoring of welding defects, the stability of welding quality, and the guarantee of welding grade. Due to the limitation of the production process, it is extremely difficult to achieve continuous and uninterrupted inspection of the longitudinally welded pipe. This will increase the probability of welding hidden dangers and quality problems, and even affect the overall working reliability of future pipeline operations.
Spiral welded pipe is also a kind of welded pipe. Its strength is generally higher than that of straight seam welded pipe. It can produce welded pipes with a larger pipe diameter from a narrower blank, and can also produce welded pipes with different pipe diameters from the same width blank. However, compared with the straight seam pipe of the same length, the weld length is increased by 30-100%,
Raw materials
Strip head and tail
2. The strip head and tail are connected by single wire or double wire submerged arc welding, and automatic submerged arc welding is used for repair welding after coiling into steel pipe.
Leveling and edge trimming
3. Before forming, the strip undergoes leveling, edge trimming, edge planing, surface cleaning and conveying, and pre-bending treatment.
Electric contact pressure gauge
4. The electric contact pressure gauge is used to control the pressure of the cylinders on both sides of the conveyor to ensure the smooth transportation of the strip.
5. Adopt external control or internal control roll forming.
Welding seam gap control device
6. The welding seam gap control device is adopted to ensure that the welding seam gap meets the welding requirements, and the pipe diameter, the amount of misalignment and the welding seam gap are all strictly controlled.
Internal welding and external welding
Shearing the pipes
Hydrostatic pressure test
9. Each steel pipe undergoes a hydrostatic pressure test, and the pressure adopts radial seal. The test pressure and time are strictly controlled by the steel pipe hydraulic device. The test parameters are automatically printed and recorded.