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What are the connection methods of seamless steel pipes

Views: 4     Author: Site Editor     Publish Time: 2022-10-08      Origin: Site

1. Compression type: Insert the pipe into the nozzle of the pipe fitting, fasten it with a nut, and compress the casing of the nozzle through the sealing ring with a screw force, which plays a sealing role and completes the connection of the pipe.

2. Welding type: The end of the pipe is beveled, and the pipe is welded in a ring shape by manual or automatic welding.

3. Flange type: The flange and the piping are welded by an annular argon arc, and fastened with quick clamps or bolts so that the gasket between the flanges can seal and complete the piping connection.

4. Compression type: insert the pipe into the pipe fitting and use a unique installation tool to press the pipe wall into a hexagon, and the internal sealing ring is also deformed into a hexagon

5. Taper thread type: that is, the outer thread and the piping are annularly welded by argon arc welding, and the inner thread pipe fittings are connected with a tapered thread to play a sealing role to complete the piping connection.


1. The production process of seamless steel pipe can be divided into two types: cold drawing and hot-rolling. The production process of cold-rolled seamless steel pipe is generally more complicated than that of hot rolling. In the sizing test, if the surface does not respond to cracks, the round tube will be cut by a cutting machine and cut into a billet with a length of about one meter.

2. Entering the annealing process, annealing should be acid-washed with acid liquid. When pickling, pay attention to whether there is a lot of blistering on the surface. If there is a lot of blistering, it means that the quality of the steel pipe does not meet the corresponding standard.

3. The delivery state of hot-rolled seamless steel pipe is generally that the hot-rolled state is 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 should be oiled, followed by several cold-drawing experiments, and the perforation experiment should be carried out after the hot-rolling treatment. If the diameter of the perforation is too large, it should be straightened and corrected.

4. The outer diameter of hot-rolled seamless pipes is generally greater than 32mm, and the wall thickness is 2.5-200mm. The outer diameter of cold-rolled seamless pipes can reach 6mm, and the wall thickness can reach 0.25mm. The outer diameter of thin-walled pipes can reach 5mm and the wall thickness is less than 0.25mm. , cold rolling has higher dimensional accuracy than hot rolling.

5. Generally, seamless steel pipes are made of 10, 20, 30, 35, 45, and other high-quality carbon steel 16Mn, 5MnV, and other low-alloy structural steel or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other combined steel hot-rolled or cold-rolled 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: the cylindrical inner thread is inserted into the cylindrical outer thread, the cylindrical inner thread is inserted into the conical outer thread, and the conical inner thread is inserted into the conical outer thread. Among them, the connection of the latter two methods is relatively tight and is a commonly used connection method.

(1) Flange flange connection. Flanging loose flanges are generally used for pipes of similar materials such as copper pipes, lead pipes, plastic pipes, etc. When flanging, different operation methods are selected according to different materials. The flanging requires smoothness without cracks and wrinkles.

(2) Threaded flange connection, which is connected with a flange with an internal thread and a steel pipe with an 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 the steel pipe are connected by welding, this kind of flange connection is widely used. The welding method is: to choose a pair of flanges and install them on the two connected pipe ends. If some equipment already has flanges, choose the flanges of the same specification to be placed in the waiting area, and spot weld a little first. Correct the verticality, and finally weld the flange to the pipe firmly.


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