Pipe coupling

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Example of a quick coupling

Pipe couplings are used to connect two pipes without flanging, welding, grooving or threading them. Pipes can be connected reversibly and with high strength.

Coupling variants

There are coupling variants for different purposes. Common names include a .:

By means of two anchor rings, which press into the surface of the pipe , the pipes are prevented from being pulled apart due to buckling or tensile loads.

  • Non-tensile couplings

This variant is suitable for an already fixed pipeline system. Since no axial tensile forces have to be absorbed by the coupling, a cable diameter of up to 4 meters is possible. However, the strength of the coupling increases as the medium pressure increases as the rubbers are pressed against the pipeline. The connection part can either be pushed over the pipe ends or placed around the pipe as a hinged variant.

  • Square coupling

Possibility to connect square tubes quickly and effectively without having to weld or flange them. The pipeline system must be fixed against shifting because it is a non-tensile coupling.

  • Step clutch

With the help of so-called step couplings, it is possible to connect pipes of different diameters and different materials.

  • Fire-Safe, FLAMSTOP and FIRE FENCE (all of the same type)

A strong connection with inlaid flame protection. It is primarily used in shipbuilding .

Materials and seals

There are V2A materials such as 304 (1.4301) and V4A materials such as 316 / 316L (1.4401 / 1.4404) for the housing. In addition to the stainless steel materials, carbon steel can also be used for the closures. If the fasteners are made of carbon steel, corrosion protection may be necessary. In the case of closures made of stainless steel (V2A / V4A) , only a lubricating coating is applied to the closures in order to avoid the so-called cold welding of the screws in the thread .

The corresponding sealing materials are used for different areas of application.

Abbreviation Chemical name Application or temperature range
NBR Nitrile butadiene rubber Hydraulics and pneumatics . Resistant up to +80 ° C with water, oils and petrol.
HNBR Hydrogenated acrylonitrile butadiene rubber Same areas of application as nitrile butadiene rubber, but with higher resistance to temperatures of +80 ° C
EPDM Ethylene-propylene-diene rubber Very good aging resistance . Suitable for UV and ozone pollution. Temperature range from +30 ° C to +100 ° C.
Viton Fluorocarbon or fluorocarbon rubber Excellent resistance to high temperatures, ozone , oxygen , mineral oils and many organic solvents. Heat resistance up to approx. +250 ° C (but only for a very short, undefined time). Cold resistance down to approx. −25 ° C

Pipe axiality (alignment)

  • Misalignment

A limited pipe-dependent offset is possible.

  • Angular deviation

A limited angular deviation of the two pipe sections can be absorbed.

  • Axis offset

By installing an intermediate piece, an axis offset can also be absorbed.

  • Pipe spacing

The possible distance between two pipe ends within a pipe can be bridged. It must be ensured that the distance between the pipe ends is always smaller than the tape insert required. Otherwise it will be pressed into the pipes between the pipes and lose its function.

  • Ovality

A deformation of the pipe cross-section can be compensated as long as the ovality is uniform and there are no “flat” spots.

Possible applications

In principle, quick-release couplings are used wherever two pipeline systems have to be connected quickly and reliably without welding or grooving. Examples are engine and shipbuilding, building technology and the water industry.

Assembly

When assembling, the pipe must have certain characteristics. The edges must be straight and deburred and care must be taken for contamination to ensure optimal strength.

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