MacGregor sealing systems ensure optimum weathertightness and effective functioning of the seal over an extended service life
Climate, cargo types and diverse customer requirements specify the criteria for selecting the right sealing solution. MacGregor sealings are manufactured according to exacting specifications to secure the optimum rubber quality for a particular application.
Our choice of original seals and sealing systems is comprehensive. It ranges from traditional sponge and solid rubber seals to advanced panel joint sealing solutions offering various operating possibilities and flexible cargo handling.
The function of sealing is to protect the cargo and to guarantee the safety of the vessel by:
Allowing for hull and coaming deformations at sea and still maintain effective sealing
Keeping water out by weathertight sealing between the hatch covers and the coaming, and in the hatch cover panel joints
Keeping cargo dry and any protective and/or inert gases inside the hold
A suitable sealing force is a prerequisite for the sealing arrangement to function correctly. This is not done by the sealing alone, but the whole coaming arrangement has to work in unison. It is of paramount importance for the tightness of the covers that the compression bar position in relation to the seal is correct, and that the support pads, stoppers and locators are arranged in an optimal way. Changes in one part o the arrangement can lead to changes in its other components. We see the system as a whole and know how to balance all its parts.
Requirements define the type of sealing
Sealing between hatch covers and coaming is generally achieved by sliding rubber packing which is fitted to the panels and tightens against the top of the coaming or against the edge of a compression bar. Sealings can be fitted for the panel joints, and some of the seals offering non-sequential operation. In the case of non-weathertight hatches, a labyrinth type gasketless seal and an open joint without drainage can be used. Non-weathertightness of covers – or reduced weathertightness for some class requirements – is in all cases to be clarified by classification societies, national authorities and the shipowner based on IACS LL64.
We have dealt with the issues relating to flexible deformations in the hull and the relative movements between the hull and hatch cover by introducing the sliding seal concept. The sealing arrangement is made up of a ridged seal section, the so-called ‘Cat-profile’, which is pressed against a flat surface. The seal is made of solid rubber material with a cross section of various cavities for producing the desired sealing force over a wide range of deflections.
The sealing type and size are chosen based on a number of criteria applied simultaneously, e.g. low friction for sliding, good wearing resistance, resistance to UV radiation, as well as a wide temperature range and magnitude of the expected variation of the compression in service.