Chemical composition cutting knowledge of stainless steel pipe!

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Chemical composition cutting knowledge of stainless steel pipe!

2020-06-19 H:32:20

All metals react with oxygen in the atmosphere to form an oxide film on the surface. Unfortunately, the iron oxide formed on ordinary carbon steel continues to oxidize, causing the rust to expand form pores. You can use paint metal (e.g., zinc, nickel chromium) for electroplating to ensure the surface of carbon steel, but it is well known that this protection is only a thin film, if the protective layer is damaged, the base steel begins to rust.

Steel resistant to weak corrosive medium (such as air, steam, water) chemically aggressive medium (such as acid, alkali salt) is also called stainless acid resistant steel. In practical application, the steel with weak corrosion resistance is usually called stainless steel. The steel resistant to chemical medium corrosion is called acid resistant steel. Due to the different chemical composition, the former can resist the corrosion of chemical medium, while the latter is usually stainless steel. The corrosion resistance of stainless steel depends on the steel. Chromium is the basic element for stainless steel to obtain corrosion resistance. When the content of chromium in steel reaches about 1.2%, chromium reacts with oxygen in corrosive medium to form a thin oxide film (self passivation film) on the steel surface, which can prevent further corrosion of steel-based stainless steel pipe. In addition to chromium, the commonly used alloy elements are nickel, molybdenum, titanium, niobium, copper, nitrogen, etc., which can meet the requirements of stainless steel structure performance for various purposes.

According to the matrix structure, stainless steel tubes are usually divided into:

1. Ferritic stainless steel contains 12% to 30% chromium. Its corrosion resistance, toughness weldability increase with the increase of chromium content. Its chloride stress corrosion resistance is better than other types of stainless steel.

2. Austenitic stainless steel, chromium content more than 18%, nickel content about 8%, a small amount of molybdenum, titanium, nitrogen other elements. It has good comprehensive performance can resist various media.

3. Austenitic ferrite duplex stainless steel has the advantages of austenitic ferritic stainless steel, has superplasticity.

4. Martensitic stainless steel has high strength but poor plasticity weldability.

5. Precipitation hardening stainless steel with good formability weldability can be used as strength material in nuclear industry aerospace industry.

According to the composition, it can be divided into CR system (sus400), Cr Ni system (sus300), Cr Mn Ni (sus200) precipitation hardening system (sus600).

First of all, prepare tools materials, check whether the specifications of pipe fittings pipes match, whether the tools are matched with stainless steel water pipe tools.

2、 For pipe cutting, use a stainless steel professional cutter to cut 15 to 50 pipes, rotate the blade twice, then tighten the blade again, then rotate it twice again until it is cut. You can't let personal force lock the blade once. Cut the pipe the end of the pipe will be damaged. After the pipe is cut to a height above DN65, insert the pipe fitting insert the rubber ring to ensure that the internal external burr is removed by hand mill, the appropriate external groove is opened to avoid inserting the sealing ring.

3、 Insert the connection.

1) Before inserting the fitting, make a deep marking line on the pipe to prevent it getting stuck in place.

2) In addition to inserting internal external oil debris at the end of the pipe, it is also necessary to keep the inner pipe of the pipe fittings clean.

3) Check that the sealing ring of the pipe fitting is complete, clean correctly placed. If there is dust, clean it up. If the seal ring is damaged, replace it.

4) Pipe fittings should be inserted slowly close to the pipe. For 304 stainless steel pipe, please immerse the pipe fittings sealing ring with clean water before inserting.

5) The two ends of the 6 m long steel pipe are mechanically cut, the pipe ends are relatively sharp to prevent direct insertion damage to the sealing ring of the pipe. It is necessary to cut off a small part of the pipe with a cutter grind the angular front end with a hand grinder. Then insert the pipe fitting press.

Fourth, in the clamping operation, the clamp jaw should be placed perpendicular to the axis of the pipe, the pipe protruding ring should be placed in the groove of the jaw to clamp. The operator can only stand on the axis of the pipe, the left right sides of the tongs.

1) For manual clamping tool, there are two fixed modules at the top bottom of the jaw. The pressure is set to output a constant pressure of 50MPa. The detection standard is to observe the gap between the upper lower jaws, one to two pressures.

2) The electric large clamping tool is driven by a cylinder driven by a 220 V power motor. The connection between the oil pipe the quick coupling shall be polluted, otherwise the dirt will enter the oil system affect the normal use of the tool. Connect the main engine the hydraulic cylinder, first turn on the power supply, then turn on the pressure relief valve, wait for the pressure gauge to rise to about 45MPa, otherwise the main engine will automatically trip, then open the pressure relief valve, then release the pressure, please turn off the power supply remove the chuck.