At present, the main production process of large-diameter steel pipes in my country is hot-rolled large-diameter steel pipes and thermally expanded-diameter steel pipes. The largest size of thermally expanded seamless steel pipes is 325 mm-1220 mm and the thickness is 120mm. Thermally expanded seamless steel pipes can produce non-national standard sizes. The heat-expanded seamless pipe is what we often call the heat-expanded pipe. A steel pipe with a relatively low density but a strong shrinkage is used to expand the diameter of the pipe by cross-rolling or drawing. A rough pipe finish rolling process. In a short period of time, the steel pipe can be thickened to produce non-standard and special-type seamless pipes with low cost and high production efficiency, which is the current development trend in the field of pipe rolling.
Large-diameter steel pipes are also called large-diameter galvanized steel pipes, which refer to welded steel pipes with hot-dip or electro-galvanized layers on the surface of large-diameter steel pipes. Galvanizing can increase the corrosion resistance of steel pipes and prolong their service life. Galvanized pipes are widely used. In addition to being used as pipeline pipes for general low-pressure fluids such as water, gas, and oil, they are also used as oil well pipes and oil pipelines in the petroleum industry, especially offshore oil fields, and oil heaters and condensation pipes for chemical coking equipment. Pipes for coolers, coal distillation washing oil exchangers, trestle piles, support pipes for mine tunnels, etc.
The forming method of large diameter steel pipe:
1. Hot push expansion method: The push expansion equipment is simple, low in cost, easy to maintain, economical, and durable, and the product specification can be changed flexibly. If you need to prepare large-diameter steel pipes and other similar products, you only need to add some accessories. It is suitable for the production of medium and thin-wall thick large-diameter steel pipes, and can also produce thick-wall pipes that do not exceed the capacity of the equipment.
2. Hot extrusion method: Before extrusion, the billet needs to be machined and pretreated. When extruding pipe fittings with a diameter of less than 100mm, the equipment investment is small, the material waste is less, and the technology is relatively mature. However, once the diameter of the pipe increases, the hot extrusion method requires large-tonnage and high-power equipment, and the corresponding control system must be upgraded.
3. Hot piercing and rolling method: Hot piercing and rolling are mainly longitudinal rolling and cross rolling. Longitudinal rolling and extension rolling are mainly limited-moving mandrel tube rolling, few-stand limited-moving mandrel tube rolling, three-roller limited-moving mandrel tube rolling, and floating mandrel tube rolling. These methods have high production efficiency, low metal consumption, good product, and control system, and are increasingly widely used.
Large diameter steel pipe processing method:
1. Rolling: The large-diameter steel pipe metal blank passes through the gap between a pair of rotating rolls (various shapes), and the material cross-section is reduced due to the compression of the rolls, and the length is increased. The pressure processing method is the most commonly used method for producing large-diameter steel pipes. The production method is mainly used to produce large-diameter steel pipe profiles, plates, and pipes. Divided into cold rolling and hot rolling.
2. Forging; a pressure processing method that uses the reciprocating impact force of the forging hammer or the pressure of the press to change the blank into the shape and size we need. It is generally divided into free forging and die forging and is often used to produce materials with large cross-sectional dimensions such as large-scale steel pipes and billets.
3. Pulling; it is a processing method in which the rolled metal blank (type, pipe, product, etc.) is pulled through the die hole to reduce the cross-section and increase the length. Most of them are used for cold work.
4. Extrusion: It is a processing method in which a large-diameter steel pipe puts the metal in a closed extrusion box, and one end applies pressure to extrude the metal from the specified die-hole to obtain a finished product with the same shape and size. It is mostly used in the production of Large-diameter steel pipes made of non-ferrous metals.
Large diameter steel pipe connection type:
1. Large-diameter steel pipe quick-connect flange type: ring-shaped argon-arc welding is performed on the flange and the matching, and the gasket between the flanges is compressed with a quick clamp, which acts as a seal to complete the matching connection.
2. Welding type of large-diameter steel pipe: circular argon arc welding is carried out on the usual socket-type pipe fittings and matching, which acts as a seal and completes the matching connection.
3. Compression type of large-diameter steel pipe: insert the pipe into the pipe fitting, the two ends of the pipe fitting are protruding U-shaped grooves, and the built-in sealing ring is connected by pressing the socket part of the special pipe fitting tool.
4. Compression type of large-diameter steel pipe: Insert the pipe into the nozzle of the pipe fitting, fasten it with a nut, and compress the casing at the nozzle part through the sealing ring with the screw force, which acts as a seal and completes the pipe connection.
5. Large-diameter steel pipe tapered thread type: the outer threaded sleeve and matching are ring-shaped argon arc welding, and the inner threaded pipe fittings are connected by a tapered thread to seal and complete the matching connection. It can be used in harsh environments such as foundation subsidence, high temperature, and high pressure.
6. Large-diameter steel pipe limit compression type: the piping adopts a flanging or port welding ring, and the connection method is a union or semi-union connection. After compressing the limit seal of the rubber sealing ring by 20%-30%, it enters the metal sealing groove. A limit seal is used to protect the sealing element. It can be used in harsh environments such as foundation subsidence, high temperature, and high pressure.
7. Large-diameter steel pipe heat-shrinkable fittings: When connecting pipes, on-site welding can be used. Welding points cannot be handled at the construction site, and heat-shrinkable pipe fittings are used as supplementary seals, which shrink under the action of heat to achieve shrinkable seals.
Post time: Aug-18-2023