Even if you are the most experienced fitter, it is always helpful to review the process so you can ensure you are using the product in the correct manner. In this guide, we provide information on technical issues related to clamping to help you diagnose and fix any problems you may encounter.
Design of pipe fittings and hose clamps
Effective clamping solutions rely on hose clamps and fittings. To achieve optimal sealing performance, the following points must be considered before installing the clamp:
Serrated profiles are generally best for sealing, however, they are not suitable for thin wall or low pressure applications.
The size of the fitting should allow the hose to stretch slightly over the fitting. If you choose an oversized fitting, it will be difficult to get it to tighten completely, but an undersized fitting can easily come loose or cause the hose to bunch up.
Regardless, the fitting should be strong enough to withstand the compressive force of the clamp, and heavy-duty clamps should only be selected if both the hose and pipe are made of strong and resilient materials
Thrust: How Diameter Affects Axial Thrust
Pressure build-up within the hose creates axial thrust, which tends to force the hose away from the end of the fitting. Therefore, one of the primary purposes of a hose clamp is to resist axial thrust to hold the hose in place.
The level of axial thrust is measured by the pressure developed in the hose and the square of the hose diameter. For example: the axial thrust of a 200mm inner diameter hose is one hundred times that of a 20mm inner diameter hose.
Therefore, we strongly recommend the use of heavy-duty hose clamps for large-diameter hoses with high pressures. Otherwise, your hose won't stay in place for long.
Correct tensioning
Any clamp must be tightened to the correct tension for correct performance. Maximum torque values are provided for all bolt, screw and worm drive clamps.
It goes without saying that the higher the input torque for a given fixture, the greater the clamping force will be. However, this number should not be used to compare the relative strength of clamps; as other factors such as threads and strap width also come into play.
Properly position hose clamps
When you tighten a hose clamp, it squeezes the hose, causing compression. The knock-on effect of this can cause the hose to deform, so it is important not to place the clamp too close to the end of the hose as there is a risk of leakage or the clamp falling off when placed. We therefore recommend that any clamp be at least 4mm from the end of the hose.
