Design and Installation of Hose Clamps

Pipe fitting design

An effective clamping solution relies, not only on the hose and hose clamp but also on the pipe fitting. In order to select a fitting for optimum sealing performance, the following points must be taken into consideration:

•  A barbed profile is normally best for sealing, however, this may not be true for thin-walled or low-pressure applications.

•  The pipe fitting should be sized in order that the hose stretches slightly over the fitting. Undersize fittings may cause the hose to bunch up, thus creating a leak path. Oversize fittings will make it difficult to apply the hose.

• The pipe fitting should be of sufficient strength to withstand the compressive force of the clamp. This is particularly relevant for heavy-duty clamps.

Diameter vs Axial thrust

The pressure inside a hose will create an axial thrust, which will tend to force the hose off the end of the pipe fitting. The purpose of a hose clamp is to retain the hose on the fitting, despite the axial thrust.

Axial thrust is proportional to the pressure in the hose and the square of the hose diameter. Therefore, for a given pressure, the axial thrust of a 200mm internal diameter hose is 100 times greater than for a 20mm internal diameter hose. For this reason, heavy-duty hose clamps are required for large diameter hoses, where the pressure is significant.