Pipe Fittings

Since pipes are not available in any length, they must be connected together to form pipelines or piping systems. Which types of pipe connections exist, and for which areas of application they are suitable, can be found in this article.

Basic classification of pipe connections

You can already divide pipe connections into very different groups. On the one hand, it is important whether the pipe connection should be permanently solid and insoluble, or whether it should be released again.

Another criterion for the pipe connection is the compressive strength of the connection. If a high pressure prevails inside the piping system, the connection must also be able to withstand such a pressure, otherwise the pipe will break quickly.

Also, the temperature of the liquids (or gases, in the industrial sector) being transported through the piping system plays a role in the selection of the connection. The medium itself, which is to be transported through the pipeline, of course, if it is not about water, but about another substance (such as certain chemicals).

Another classification can be made after the weldability. For weldable materials, other connections must be made than for non-weldable materials.

Types of connections

The following briefly describes the most important and most common pipe connections.

Welding of pipes

Welded connections are universal pipe connections that are neither pressure-sensitive nor temperature-sensitive. They can be used both in the high and in the low pressure range. The temperature of the medium does not matter either.

During welding, the pipes are joined inseparably. The structure is very narrow and therefore completely dense. When welding, a distinction is made depending on the angle and overlap of the pipes to be joined different shocks:

  • butt
  • lap joint
  • Bördelstoß
  • parallel joint
  • T-joint

In addition, corner joints and multiple joints can be made. For the execution there are numerous regulations, which are to ensure the durability of a weld.

In the case of highly sensitive pipe connections, which must necessarily be completely leakproof, testing of the welded joints is often carried out retrospectively using various technical methods. This is the case with pipelines.

Flanges of pipes

Pipes can be flanged together. Such compounds also withstand high pressures, wherein the contact pressure of the flanges is crucial for the tightness. However, flange connections are unsuitable for transporting higher temperature media as the seal between the flanges could be damaged.

Flange connections are solvable. There are also many standards for flanges and they are available in different versions (vacuum flange, blind flange and others).


Tubes can be threaded. They are a simpler alternative to flanges for smaller pipe diameters. Partially also screw connection parts are used. Screw connections are

  • solvable
  • pressure stable up to several hundred bar pressure
  • usable up to medium temperatures

Sleeves and cuffs

Sleeves are suitable only at low pressure and low temperature inside pipelines. Cuffs are also commonly used to connect tubes of different materials together. A connection of pipes with different diameters can be made via cuffs.

Other connection types

Plug connections, as known for example from sewers and connections, are also possible.

In addition, it is still possible:

  • Brazing pipes (soft or brazing)
  • glue
  • clamp (using a clamping ring)

Video Board: Pipe Fittings | Piping Analysis