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 for plating to ensure the surface of carbon steel, but as we all know, 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 chemical aggressive medium 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 oxide film on steel surface. In addition to chromium, the commonly used alloy elements are nickel, molybdenum, titanium, niobium, copper, nitrogen, etc., to meet the performance requirements of stainless steel structure various uses.
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 containing more than 18% chromium also contains about 8% nickel a small amount of molybdenum, titanium, nitrogen other elements. It has good comprehensive performance is resistant to various media corrosion.
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 has good formability weldability, can be used as strength material in nuclear industry, aviation aerospace industry.
According to the composition, it can be divided into CR system, Cr Ni system, Cr Mn Ni precipitation hardening system in stainless steel seamless steel pipe plant.
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、 To cut the pipe, use a stainless steel professional cutter to cut 15-50 tubes. Rotate the blade twice, then tighten the blade, then rotate it twice again until it is cut. Do let personal force lock the blade once to cut the pipe, otherwise the pipe end will be damaged. After cutting the pipe 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.
Third, insert the connection.
1) Before inserting the fitting, make a deep marking line on the pipe to prevent it getting stuck in place.
2) The internal external oil foreign matters at the end of the pipe shall be inserted, the inner pipe of the pipe fittings shall be kept clean.
3) Check whether the sealing ring of the pipe fitting is complete, clean, correctly placed, whether there is dirt, if the sealing ring is damaged, replace the sealing ring.
4) Insert the fitting tightly slowly into the pipe. For 304 stainless steel pipe, please immerse the pipe fittings sealing ring with clean water before inserting.
5) Mechanical cutting is carried out on both ends of 6-meter-long steel pipe to make the pipe end more sharp, so as to prevent direct insertion of damage to the sealing ring of the pipe. It is necessary to cut the pipe end with a cutter grind off the angle front with a hand grinder. Then insert the pipe fitting press.
4. For clamping operation, place the jaw of the caliper perpendicular to the axis of the pipe fitting, place the convex ring of the pipe fitting in the groove of the jaw for clamping. The operator can only stand on the pipeline axis, on the left right sides of the tongs.
1) For manual clamping tool, the jaw is two fixed modules, the pressure is set as constant output, the pressure is 50MPa, the detection standard is to observe the joint of upper lower jaw, the pressure can be one two times.
2) The large electric clamping tool is driven by a cylinder driven by a 220 V power motor. The connection between the tubing the quick connect fitting must be contaminated. Otherwise, dust 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.