Hatch Covers

December 1991

Steel hatch covers are designed to cope with some of the most hostile environmental conditions known, and the corrosive elements of seawater can be devastating if not kept in check. This article summarises some of the more common problems which can lead to water ingress and result in claims.

The main areas of concern are the rubber seals and compression bar. These two parts should be regularly inspected. The ageing of a rubber seal cannot be prevented, but by following recommended service procedures, it should be possible to ensure that its efficiency is maintained throughout its working life. Careless painting of channels can cause hard spots, and rust scale should also not be allowed to form underneath the rubber packing, which if allowed will cause high spots. If the packing is to be renewed, it is essential that the whole strip be replaced, because otherwise there will be a lack of uniformity between the compression strength of each piece. Poorly maintained rubber seals are frequently the cause of water ingress, and every effort should be made to ensure that the seals are carefully inspected at every opportunity to establish that there is a satisfactory compression of the rubber onto the compression bars.

It is a natural assumption, because the compression bars are solid steel, to assume that no harm can come to them. But, in fact, good compression bars are as necessary as good rubber seals. The obvious cause of damage to these bars is by impact from cargo which is being moved into or out of the holds. These bars also may become damaged over a period of time by cargo wires continually passing across the same area, which eventually causes the original right angled edge of the bar to become rounded. Furthermore, if no care is taken to combat corrosion then the top surface of the bar will develop high and low spots, which will prevent the proper seating of the rubber seals. Corrosion is particularly likely to effect the compression bars of the cross joints. Experience has shown that close attention should be paid to the cross joints between the panels, which must be pressed firmly and evenly together. The pressure on the cross joints depends mainly on the closing action of the covers and when the hatch covers are fully closed the correct compression of the cross joint seal should be automatically achieved. If there is not an effective seal then either the packing has become too heavily compressed, and requires renewal, or the compression bar on the adjacent panel has become bent or corroded. There is a likelihood that the cause may be a combination of both these defects.

Steel hatch covers have been designed so that water drains away. It is thus important to ensure that drain holes, water ways and covings are kept clean. It should however also be possible to clean and grease working parts and screwheads with sufficient regularity to prevent them from becoming too stiff to function correctly. Particular attention should be paid to the hatch cleats, which are increasingly allowed to become unworkable because of rust.

It is becoming more and more the practice to cover the cross joints with a heavy adhesive tape. Although these tapes can be used as an additional precaution when carrying sensitive cargoes. experience has shown that during heavy weather they tend to be washed away. Indeed, the use of such tapes is sometimes interpreted by claimants as evidence that the steel hatches were probably leaking before the commencement of the voyage. Thus, heavy adhesive tape can only he regarded as a temporary or additional precaution, and cannot take the place of proper maintenance or repairs.

There can be no substitute for well maintained hatches and all vessels fitted with steel hatch covers should have on board the manufacturers' manuals, which deal extensively with the points mentioned in this article. Most leading manufacturers have representatives in the principle sea ports, and should a Master/Owner be unhappy with the condition of the hatches, then it is recommended that the advice of the manufacturers is sought.