Made During Hose Installations and How to Remedy Them
One of the key mistakes made in the use of dredging hose is in the positioning of centres of rotation. There is only one correct position and this must always be on the line of intersection of the axis extending from the centre lines of the connecting pipe perpendicular to the end face of the flange (1). The distance from the point of intersection to each end face of the connecting flange must be exactly the same on both sides. The sum of these two measurements thus equals the length of the hose.
This principle is shown in the diagram (2). It also applies to joints in two planes (universal joints or gimbals).
|Don't try to reduce the bending angle of the hose as shown above.|
|Don't use retaining clamps to force hoses into 'unnatural' positions. Don't lay hose over uneven ground when,
for example, connecting floating lines to the land lines. In both cases the dredged material will quickly wear the hose.|
|Don't mount hose directly after pipe bends. It is held too rigidly and a small section will
wear quickly. Instead, use the hose as the bend so that wear is distributet over the entire outer curve. The hose may be turned through
60 deg. or 90 deg. to distribute wear more uniformly, and direction of wear may be changed by reversing the hose.|
|Don't use a long, incorrectly mounted hose when a short, less expensive and correctly mounted section will suffice.|
|Don't fit hose too closely in front of or behind a centrifugal pump. The rotation of the dredged material,
especially in very long delivery lines, is transmitted to the pipeline near the pump and greatly increases wear on the hose.|
This is just a selection of the most common mistakes made in installing hose. As a general rule, if any folding or kinks are found during operations the hose is usually not being used correctly.