The stainless steel square tube is a hollow long strip of steel, which is called a square tube because the cross section is square. A large number of pipes are used to transport fluids, such as oil, natural gas, water, gas, steam, etc. In addition, when the bending and torsional strength are the same, the weight is lighter, so it is also widely used in the manufacture of mechanical parts and engineering structures.
The stainless steel square tube is a hollow long strip of steel, which is called a square tube because the cross section is square. A large number of pipes are used to transport fluids, such as oil, natural gas, water, gas, steam, etc. In addition, when the bending and torsional strength are the same, the weight is lighter, so it is also widely used in the manufacture of mechanical parts and engineering structures
Classification of stainless steel square tubes: Square tubes are divided into two categories: seamless steel tubes and welded steel tubes (seamed tubes). According to the cross-sectional shape, it can be divided into square and rectangular tubes. Round steel tubes are widely used, but there are also some special-shaped steel tubes such as semicircular, hexagonal, equilateral triangle, and octagonal.
For stainless steel square pipes under fluid pressure, hydraulic tests are required to check their pressure resistance and quality. It is qualified if no leakage, soaking or expansion occurs under the specified pressure. Some steel pipes also need to be coiled according to standards or requirements of the buyer. Edge test, flaring test, flattening test, etc.
Square tube specification: 5*5~150*150 mm Thickness: 0.4~6.0 mm
Square tube material: 304, 304L, TP304, TP316L, 316, 316L, 316Ti, 321, 347H, 310S.
Round steel preparation → heating → hot rolling piercing → head cutting → pickling → grinding → lubrication → cold rolling processing → degreasing → solution heat treatment → straightening → pipe cutting → pickling → finished product inspection.
Metals can react with oxygen in the atmosphere to form an oxide film on the surface, and the iron oxide formed on ordinary carbon steel will continue to oxidize, causing the rust to continue to expand and eventually form holes. This can use paint or oxidation-resistant metal plating to protect the surface of carbon steel, but this protective layer is only a thin film. If the protective layer is damaged, the steel below will start to rust again. Whether the stainless steel pipe is corroded is related to the chromium content in the steel. When the chromium content in the steel reaches 12%, in the atmosphere, a layer of passivated and dense chromium-rich oxide is formed on the surface of the stainless steel pipe to protect the surface and prevent corrosion. further reoxidation. This kind of oxide layer is extremely thin, and the natural luster of the steel surface can be seen through it, making the stainless steel have a unique surface. If the chromium film is damaged, the chromium in the steel and the oxygen in the atmosphere will regenerate a passivation film to continue to play a protective role. In some special environments, stainless steel will also fail due to some local corrosion, but unlike carbon steel, stainless steel will not fail due to uniform corrosion, so the corrosion allowance is meaningless for stainless steel pipes
