You must know! Common pipe fittings and pipe connection methods

In the configuration of pipelines, in order to connect pipe sections or change the direction and diameter of pipes, special parts are often required, such as elbow passage (four-way), short pipe and reducer pipe (size), flange and blind plate (figure-8 blind, etc.), these parts are collectively referred to as pipe fittings. Today I will talk to you about common pipe fittings and pipe connection methods.

What are the common pipe fittings?

According to the use and material used, pipe fittings can be divided into steel pipe fittings, cast iron pipe fittings and non-metallic pipe fittings. Most of the refining and chemical systems use steel pipe fittings, steel pipe fittings are suitable for a variety of media and uses of pipelines, the current forming products mainly include pressed elbows, reducers and tees.

Pressing elbow has seamless elbow and welding elbow two, seamless elbow is made of 10 steel, 20 steel or stainless steel seamless steel pipe pressed on a special mold, it is divided into 90 ° and 45 ° two, of which commonly used is 90 ° elbow. The welding elbow is made by stamping and forming two tiles of 10 steel and 20 steel, and it is divided into two types: 90° and 45°. When the pipe diameter is small and the medium pressure is large, seamless elbows are commonly used, and welding elbows are mostly used for pipelines with large diameter and low pressure.

Short pipes are used in chemical pipelines for easy installation and disassembly. The diameter of the two ends of the short tube is called a reducer. Reducers include concentric reducers and eccentric reducers, which can be stamped with seamless steel pipes or coiled with steel plates.

Tee includes equal diameter tee and reducer tee.

Commonly used pipe fittings on small diameter pipes are steel unions, steel thread shortings, steel pipe hoops, etc. In addition, valves are also one of the most widely used accessories in pipelines.

In addition, for the convenience of pipeline installation and maintenance, it is necessary to install a pipe flange in the pipeline, and the end of the pipeline is installed with a flange cover, the flange cover is the same size as the flange, and the blind plate is inserted between the two flanges.So what kind of connection method can connect these pipe fittings with the pipeline? Let's talk about how the pipes are connected.There are four connection methods of pipes: welding, flange connection, threaded connection and socket connection. In the project, welding connections and flange connections are more used.The welded connection of the pipeline has high strength, good tightness, no accessories required, low cost, easy to use, suitable for transporting steel pipes of various media, and its disadvantage is that it cannot be disassembled. When welding the connection, the distance between the two parallel welds is not small, the outer diameter of the pipe is not small, and it should not be less than 200mm or more. In order to avoid cross welds, if the pipe made of steel plate roll welding should be staggered by more than 200mm when aligning. The butt weld of the pipe should be more than 100mm away from the bracket.Flange connection is a connection method that connects the pipe fittings together by connecting the pipe and the pipe end (flange). The flange connection is flexible and convenient, and the pipeline can be cleaned or replaced regularly; However, various specifications of flanges are required, and steel is consumed a lot, and due to temperature differences, pressure fluctuations and corrosion, sometimes leakage occurs at the joint, resulting in medium loss and even accidents.

Threaded connections are mainly used in pipelines of production or domestic water and heating facilities, and are also widely used in the connection between cooling water pipes or pressure gauges of pumps and the impulse line of control valves. This connection requires a variety of accessories such as union joints, tees, pipe hoops, wire plugs, etc. The threaded connection is easy to disassemble and assemble, but the construction is troublesome, and the joint is also prone to leakage.

The socket connection is mainly suitable for the connection of cast iron pipe, ceramic pipe, concrete pipe and plastic pipe.

socket connection

For pipelines with electrostatic grounding requirements, the resistance value between each connection joint and the ground resistance value of the pipeline system should be measured. If the resistance value exceeds 0.03Ω, jump wires and ground leads should be set. For stainless steel pipes and titanium pipes, the jumper conductor and grounding lead shall not be directly connected with the titanium pipe and the stainless steel pipe, and the titanium plate and stainless steel plate shall be used for transition.