Types of pipe connection

Pipe connection is varied, the commonly used have Butt weld, Flanged, Threaded, Socket weld, Glued, Brazed and Grooved end.

You assign connection types in the Connector Properties dialog box as you build fittings content using the Content Builder (see Adding Connectors to a Parametric Fitting). Assigned connection types are then displayed on the Connection Assignments tab of the Pipe Layout Preferences dialog box.

Unthreaded Connections are not threaded, must be either welded or bolted together. 

The different orientations of pipe connection types:

Butt welds:

Butt welds are welds where two pieces of metal to be joined are in the same plane. These types of welds require only some kind of preparation and are used with thin sheet metals that can be welded with a single pass. Common issues that can weaken a butt weld are the entrapment of slag, excessive porosity, or cracking. For strong welds, the goal is to use the least amount of welding material possible. Butt welds are prevalent in automated welding processes, such as submerged-arc welding, due to their relative ease of preparation. When metals are welded without human guidance, there is no operator to make adjustments for non-ideal joint preparation. Because of this necessity, butt welds can be utilized for their simplistic design to be fed through automated welding machines efficiently.

connection pipe butt weld - Types of pipe connection

No extra objects are added.

Fittings and pipe segments connect directly to each other.

Welding connection characteristics
The interface is firm and tight, and the weld strength generally exceeds 85% of the strength of the pipe, even exceeding the strength of the base metal.
The welded joint is a direct connection between the pipe sections, the structure is simple, the pipes are beautiful and tidy, and a large number of shaped pipe fittings are saved.
The interface is tight and no filler is used, which can reduce maintenance work.
The interface is not limited by the pipe diameter and the operation speed is fast.
The welded connection interface is a fixed interface, which is difficult to connect and disassemble. If it is necessary to repair and clean the pipeline, the pipeline should be cut off.
Metal tube welding
Welded joints are mainly used for butt joints, welded flanges and other flexible ports for water supply pipes. Welding methods usually include gas welding, manual welding and automatic arc welding, and contact welding. The pipeline should be thoroughly cleaned and inspected before welding.
When the steel pipe is opposite, the longitudinal welds shall be staggered by more than 100 mm arc length, and there shall be no cross-shaped welds; the welds shall not be placed in the walls of buildings, structures, etc.
When the steel pipe is rolled, the longitudinal welds of each pipe shall not be aligned on the same straight line. The distance between the longitudinal welds of two adjacent pipes shall be greater than 3 times of the wall thickness and not less than 100 mm; The distance between two adjacent longitudinal welds shall not be less than 300 mm.
There shall be no welds in the curved part of the pipe, and the bending point of the butt weld shall not be less than the outer diameter of the pipe and not less than 100 mm (except for the welded elbow). There should be no annular welds at the pipe supports.

Flanged All types

A flange is a plate or ring that is attached to a pipe. Two flanged pipe then create a tight seal by being bolted together.

connection pipe flanged all types - Types of pipe connection

  • Fitting to pipe: Flanges are typically included on fittings. A separate flange is added to the pipe segment.
  • Pipe to pipe: A separate flange is added to each pipe end to create the connection.
  • Fitting to fitting: Fittings with inherent flanges connect directly to each other. No separate flanges are added to the connection.

Flange connections are two pipes, fittings or equipment. A detachable joint that is first fixed to a flange, then a flange pad is placed between the two flanges, and the two flanges are bolted together to make them tightly coupled.
This connection is mainly used for the connection of cast iron pipes, rubber-lined pipes, non-ferrous metal pipes and flange valves, and the connection between process equipment and flanges is also flanged.
The flange connection of the steel pipe needs to be disassembled and connected to the flanged valve parts, equipment, instruments, etc. The flanges are available in cast iron and steel. The connection between the flange and the pipe has three kinds of flanged loose joints, threaded joints and welded joints. In the pipeline installation, the connection method of flat welded steel flanges is often used.
Flanged flange connection. Flanged loose flanges are generally used for pipes of similar materials such as copper pipes, lead pipes, plastic pipes, etc. Different operating methods are used according to different materials when flanging, and the flanging is required to be flat without cracks and wrinkles.
Threaded flange connection, connected with internally threaded flanges and externally threaded steel tubes. These flanges are mostly cast iron and can be used for low pressure pipe connections.
Welded flange connection, flange and steel pipe are welded, this flange connection is widely used. The welding method is as follows: select a pair of flanges, respectively, which are installed at the two pipe ends that are connected to each other. If some equipments already have flanges, then select the same type of flange sleeves to be treated, first spot welding, Correct the verticality and finally weld the flange to the tube firmly. The inner and outer faces of the flat welded flange must be welded to the pipe

Threaded, Socket weld, Glued, Brazed

The pipe is the male fitting and the socket is equivalent to a female fitting. To provide a tight seal it is best to line the outside of the pipe and the inside of the socket with a sealant.

connection pipe threaded - Types of pipe connection

Socket welds require a pipe and socket connection.

  • Fitting to pipe: Pipe segments typically have inherent male ends, and fittings are typically female. The pipe inserts directly into the fitting.
  • Pipe to pipe: A female coupling is inserted between the pipe segments.
  • Fitting to fitting: Fittings connect directly to each other.


The connection of the pipe thread has three ways: a cylindrical internal thread is inserted into the cylindrical external thread, a cylindrical internal thread is inserted into the conical external thread, and a conical internal thread is inserted into the conical external thread. Among them, the latter two methods are more closely connected and are commonly used connection methods.
In order to increase the tightness of the pipe thread interface and to prevent disassembly due to thread rust during maintenance, the thread is generally filled. therefore. The filler should be able to fill the gap and prevent corrosion. In order to ensure that the interface is long and tight, the pipe threads must not be too loose. Do not use more filler material to prevent leakage. It should be noted that the packing can only be used once in the threaded connection and should be replaced if it is removed.
The appropriate pipe wrench should be used to tighten the pipe thread. Do not use a sleeve on the handle of the pipe wrench to tighten the pipe. After the pipe thread is tightened, 1 to 2 threads (ie, thread tails) shall be exposed outside the pipe or valve. Do not screw all the threads in, the excess hemp should be cleaned and treated with anti-corrosion treatment. When installing the pipe fittings, pay attention to the position and direction of the pipe fittings.

Socket weld

Socket welding is to pipe the pipe into the valve body for welding, and the shape of the internal thread connection is similar after molding. Generally speaking, carbon steel pipes and stainless steel pipes of 2″ or less are used for socket welding; stainless steel pipes are also used for butt welding below 2″, such as flange flange flange; titanium pipe, duplex steel, nickel base Alloys and the like are basically used for butt welding.
The difference

  1. Socket welds form fillet welds, while butt welds form butt welds. From the strength and stress state of the weld, the butt joint is better than the socket. Therefore, in the case of high pressure level and the use condition is bad, the form of docking should be adopted.
  2. Socket welding is generally used for small diameters of DN40 or less, which is economical. Butt welding is generally used for DN40 or higher. The socket connection form is mainly used for small diameter valves and pipe, pipe fittings and pipe welding. Small-diameter pipes generally have a thin wall thickness, are easy to be misaligned and ablated, and are difficult to weld, and are more suitable for socket welding. In addition, the socket of the socket welding has a reinforcing effect, so it is also used under high pressure. However, socket welding also has shortcomings. One is that the stress condition after welding is not good, and the welding is not welded. The gap inside the pipe system is left. Therefore, the pipe system used for crevice corrosion sensitive media and the pipeline system with high cleaning requirements are not suitable. Use socket welding. Furthermore, for ultra-high pressure pipes, even small-diameter pipes have a large wall thickness, and it is possible to avoid socket welding by using butt welding.
  3. The former must be one big and one small in diameter before it can be inserted into the welding. The latter diameters can be the same or different. 2. The welding groove form is different. 3 welding process is different. The strength is not the same after welding.
  4. The lower pressure grades are mostly socket welds, and the high pressure grades are often butt welds. Butt welds are 100% tested for flaw detection to ensure no leaks.
  5. As the name suggests, socket welding is to insert the tube into the welding, but the butt welding is directly welded to the nozzle. Generally, the requirements for butt welding are higher than those for socket welding, and the quality after welding is good, but the detection method is relatively strict. For the welding to do the radiographic inspection, the socket welding can do the magnetic powder or the penetration test (like carbon steel for magnetic powder, stainless steel for penetration). If the fluid in the pipeline does not require high welding, it is recommended to use socket welding for easy inspection.


  • There is no problem with the beveling;
  • There is no problem with the wrong side;
  • The welding position can be adjusted to flat welding.

Grooved end

A grooved end fitting has a groove or shoulder along the edge. This fittings groove allows for a seal without the need for welding.

connection pipe grooved - Types of pipe connection

  • Fitting to pipe: Fittings and pipe segments are considered to have grooved ends that are ready to accept a coupling. A coupling is added to connect the fitting and pipe.
  • Pipe to pipe: A coupling is added to connect the pipe segments.
  • Fitting to fitting: A coupling is added to connect fittings.

The Piping domain includes a connection type called Same Connection. When Same Connection is configured for a pipe object that is attached to a hub, connector 1 inherits the connection type of the connection type on connector 2 of the attached hub.

Source: Network Arrangement – China Steel Pipes Manufacturer – Yaang Pipe Industry Co., Limited (www.steeljrv.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

If you want to have more information about the article or you want to share your opinion with us, contact us at sales@steeljrv.com

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