Spiral steel pipe is also called a spiral steel pipe, which is generally referred to as a spiral steel pipe with a diameter of more than 1 meter. Steel pipes are subject to water pressure, tortuosity and pressure. Flat and other experiments have certain requirements on the surface quality. The general delivery length is 12 meters, often requiring fixed delivery. A metal material with a yielding phenomenon, the stress of the sample is not added (persistently stable) during the stretching process, and the stress at the time of elongation is continued, which is called the yield point.
If the force attack declines, the upper and lower yield points should be distinguished. The unit of the yield point is N/mm2 (MPa). The sample is connected during the stretching process. The maximum force (Fb), the stress (σ) obtained from the original cross-sectional area (So) of the sample, is called the tensile strength (σb), and the unit is N/mm2 (MPa). It shows the maximum ability of metal materials to resist damage under tensile forces.
In the tensile test, the percentage of the length added by the gauge length after the sample is broken and the length of the original gauge length is called the elongation. Indicated by σ, the unit is percent. Generally, the spiral seam high-frequency welded steel pipe (SY5039-83) for low-pressure fluid transportation is a hot-rolled steel strip which is used as a tube blank and is often spirally formed at a constant temperature.
High-frequency lap welding is used for welding spiral high-frequency welded steel pipes for general low-pressure fluid transportation. Spiral-welded steel pipe (SY5040-83) for piling is made of hot-rolled steel strip as tube blank, regular temperature spiral forming, double-sided submerged arc welding or high frequency welding, used for civil engineering structures, wharfs and bridges. Steel pipes for equal root piles.
