Views:1 Author:Site Editor Publish Time: 2020-10-14 Origin:Site
Seamless steel pipe thread connection process
1. The production process of seamless steel pipes can be divided into two types: cold-drawn and hot-rolled. The production process of cold-rolled seamless steel pipes is generally more complicated than that of hot-rolled. The tube billet must first undergo three-roll continuous rolling, and then it must be extruded. In the sizing test, if the surface does not respond to cracks, the pipe will be cut by a cutting machine and cut into a blank of about one meter in length.
2. In the annealing process, the annealing should be pickled with acid liquid. When pickling, pay attention to whether there is a large amount of blistering on the surface. If there is a large amount of blistering, it means that the quality of the steel pipe does not meet the corresponding standards.
3. The delivery status of hot-rolled seamless steel pipes is generally hot-rolled and delivered after heat treatment. After the quality inspection, the hot-rolled seamless steel pipe must be strictly hand-selected by the staff. After the quality inspection, the surface must be oiled, and then followed by multiple cold drawing experiments. After the hot rolling treatment, the piercing experiment must be carried out. , If the perforation is too large, it must be straightened.
4. The outer diameter of hot-rolled seamless pipe is generally greater than 32mm, and the wall thickness is 2.5-200mm. The outer diameter of cold-rolled seamless pipe can be up to 6mm and the wall thickness can be up to 0.25mm. The outer diameter of thin-walled pipe can be up to 5mm and the wall thickness is less than 0.25mm. , Cold rolling has higher dimensional accuracy than hot rolling.
5. General seamless steel pipes are made of 10, 20, 30, 35, 45 and other high-quality carbon steels such as 16Mn, 5MnV and other low-alloy structural steels or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other composite steels by hot rolling or cold rolling. of. Seamless pipes made of low carbon steel such as 10 and 20 are mainly used for fluid transportation pipelines.
6. There are three ways to connect the pipe thread: cylindrical internal thread into cylindrical external thread, cylindrical internal thread into conical external thread and conical internal thread into conical external thread. Among them, the latter two methods are more closely connected and are commonly used connection methods.
(1) Flange flange connection. Flanging loose flanges are generally used for pipes of similar materials such as copper pipes, lead pipes, and plastic pipes. When flanging, different operation methods are selected according to different materials. Flanging needs to be flat without cracks and wrinkles.
(2) Threaded flange connection, use a flange with internal thread to connect with a steel pipe with external thread. This flange is mostly made of cast iron and can be used for the connection of low-pressure pipelines.
(3) Welded flange connection. The flange and steel pipe are connected by welding. This kind of flange connection is widely used. The welding method is: select a pair of flanges and install them on the two pipe ends that are connected respectively. If some equipment has flanges, select the flanges of the same specification to be set, and spot welding first. Correct the verticality, and finally weld the flange and the pipe firmly.