316 Stainless steel pipe fittings can be divided into 316 stainless steel three-way, 316 stainless steel flange, stainless steel four-way pipe and so on. 316 Stainless steel tee pipe is used for the gathering of three pipes; Stainless steel four-way pipe is used for the gathering of four pipes; Stainless steel reducing pipe is used where two pipes of different diameters are connected. A 316 stainless steel flange is a part that connects a stainless steel pipe to a pipe and is connected to the pipe end.
316 Stainless Steel Tee and Stainless Steel Cross
Stainless steel tees are pipe fittings and pipe connectors. The stainless steel spool is a kind of pipe fitting used at the branch of the pipeline. Stainless steel tee and stainless steel spool are divided into equal diameter (the ends of the nozzle are the same size) and different diameter (the size of the branch pipe is smaller than that of the main pipe). It is applied to the branch pipe of the main pipeline.
316 stainless steel three-way pipe and 316 stainless steel four-way pipe forming principle
316 Stainless steel tee and stainless steel cross are a kind of pipe fittings used in pipeline branches. For the use of seamless pipes to manufacture tee, the commonly used processes are hydraulic bulging and hot pressing. The hydraulic bulging process of the stainless steel tee can be formed at one time, the production efficiency is high, and the wall thickness of the main pipe and the shoulder is increased. Hot pressing has a wide adaptability to materials, and is suitable for low carbon steel, alloy steel, and 316 stainless steel materials; especially for crosses with large diameters and thick tube walls, this forming process is usually used.
316 Stainless Steel Flange
Stainless steel flanges are also called flanges or flanges. The 316 stainless steel flange is the part that connects the 316 stainless steel pipe to the pipe, and is connected to the pipe end. There are holes on the 316 stainless steel flange, and the bolts make the two flanges tightly connected. The flanges are sealed with gaskets. Flange is divided into threaded connection (wire connection) flange and welding flange. Stainless steel flange pipe fittings, butt welding flange electrodes have good corrosion resistance and oxidation resistance, and are widely used in chemical, fertilizer, petroleum, and medical machinery manufacturing.
316 Stainless steel flange is a disc-shaped part, which is the most common in pipeline engineering. The flanges are used in pairs and with the matching flanges on the valve. Add a gasket between the two flanges and fasten them with bolts. Different pressure flanges have different thicknesses and use different bolts. The low-pressure small diameter has a wire flange, and the high-pressure and low-pressure large diameters use welded flanges.
The main 316 stainless steel flange function
1. Connect the pipeline and maintain the sealing performance of the pipeline;
2. It is convenient to replace a certain section of pipeline;
3. It is easy to disassemble and check the pipeline condition;
4. It is convenient for the sealing of a certain section of pipeline.
316 Stainless steel flange parameters
PN is the nominal pressure, which means that the unit is 0.1MPa in the international system of units and kgf/cm2 in the engineering unit system. Pipe flanges are commonly used bar (ie, kilogram force kgf/cm2, 1bar=0.1MPa) equipment flanges are commonly used MPa. The determination of the nominal pressure should be based not only on the maximum working pressure, but also on the maximum working temperature and material properties, not just the fact that the nominal pressure is greater than the working pressure.
DN is a parameter indicating the flange size.
Precautions for the 316 stainless steel flanges use
1. In order to prevent the corrosion between the eyes due to the heating of the flange cover, the welding current should not be too large, which is about 20% less than that of the carbon steel electrode, the arc should not be too long, and the layers are cooled quickly, and a narrow weld bead is appropriate.
2. The electrode should be kept dry when used. The titanium calcium type should be dried at 150°C for 1 hour, and the low-a hydrogen type should be dried at 200-250°C for 1 hour (do not repeat the drying many times, otherwise the coating will be easy to crack and peel) to prevent The coating of the electrode sticks to oil and other dirt, so as not to increase the carbon content of the weld and affect the quality of the weldment.
3. When 316 stainless steel flange pipe fittings are welded, carbides are precipitated by repeated heating, which reduces corrosion resistance and mechanical properties.
4. The chrome 316 stainless steel flange pipe fittings have large hardening American standard flanges after welding, and are prone to cracks. If the same type of chromium stainless steel electrodes (G202, G207) are used for welding, preheating above 300°C and slow cooling after welding must be performed at about 700°C. If the weldment cannot be subjected to post-weld heat treatment, the 316 stainless steel flanged pipe fitting electrode (A107, A207) should be used.
How to choose 316 stainless steel flange
In order to improve corrosion resistance and weldability, 316 stainless steel flanges appropriately increase the appropriate amount of stable elements Ti, Nb, Mo, etc., and the weldability is better than that of chrome stainless steel flanges. When using the same type of chrome stainless steel flange electrode (G302, G307), it should be preheated above 200°C and tempered at about 800°C after welding. If the weldment cannot be heat treated, the stainless steel flanged pipe fitting electrode (A107, A207) should be used.
The national standard flange is a flange produced according to the size and tolerance range required by the national standard. It is different from the flange sheet produced not according to the standard size, which is also called the second standard flange (some people call it a non-standard flange is incorrect). Usually, some unscrupulous merchants will reduce the thickness and outer diameter of the flange to achieve the purpose of saving materials, and also use scrap steel or scrap steel to process flanges. Usually this kind of steel is waste with substandard chemical composition and mechanical properties. What’s more, the flanges are produced by private steelmaking in black steel plants. The steelmaking technology used in this private steelmaking is outdated and cannot guarantee the mechanical properties and welding performance. It may not be able to be welded with the steel pipe during use, or the steel itself has cracks and pores. It also leaks after welding. Therefore, try to use national standard flanges when purchasing flanges. If the funds are limited to choose the second standard flange, you must carefully observe and measure the flange size to avoid being fooled.