Clay drag head
Dredging in clayey soils with standard dragheads means a lot of trouble. During dredging, the clay will start blocking the draghead. This will bring down the production rate in three steps:
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the excavation rate will drop as the draghead becomes virtually smaller
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when the blockage of the head is too important, the dredging process has to be interrupted to bring the head on deck and remove the clay by hand. This means a loss of operational time
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to minimize the risk of blocking of the head, the excavation rate will be actively reduced
Depending on the clay type, production can drop to very low values. On top of this, such a job can be very demanding for the crew.
To solve this problem, the clay head was developed to significantly reduce the clogging of the head, meaning higher production rates and better working circumstances for the crew.
Design
The most important part is the visor. To reduce the risk of clogging, several elements are incorporated in the design:
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minimizing the surface of the visor where the clay can stick to
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the rear part of the visor is a large element that can be opened and closed by hydraulic cilinders. Opening of this part automatically scrapes the clay off the walls and creates a huge flushing effect
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the large element is fitted with nozzles for waterjetting that are pointing towards the inside of the head. Those waterjets sweep the entire head when the large element is actuated, removing clogging clay
The fixed part of the head is fitted with a special grid that prevents the clay entering the head and helps removing clogging clay out of the visor.