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MAINTENANCE
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  • MAINTENANCE

  • What is corrosion?Apart from the efficient lubrication of all moving parts, probably the most important part of ship maintenance is the preservation of the hull and its component parts.

  • What is corrosion?This can only be achieved by eliminating (or since this is normally too expensive), preventing and reducing corrosion.

  • What is corrosion?Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings.

    In the most common use of the word, this means electrochemical oxidation of metals in reaction with an oxidant such as oxygen.

  • What is corrosion?Oxidation of the iron atoms in solid solution is an example of electrochemical corrosion known as rusting.

  • What is corrosion?In other words, corrosion is the wearing away of metals due to a chemical reaction.

  • PaintingTo prevent metal corroding it is necessary to coat the metal with a preparation that will exclude the atmosphere.

    Normally paint is used for this purpose, some fittings may be galvanised, it is nevertheless usual to paint over the galvanizing.

    Do not use a lead(Pb) based paint on galvanizing or aluminium.

  • What is galvanizing?Its a metallurgical process that is used to coat steel or iron with zinc.

  • With an old shipBefore paintingAll superstructure paintwork must be well cleaned by washing with soda or other solution and all dirt, oil, grease, etc., removed.

    Then, the paintwork must be rinsed with clean fresh water and all trace of the soda or cleaning agent removed.

    Loose paint is lifted with a scraper, heavy rust will usually loosen when hit with a hammer.

  • With an old shipBefore painting

  • With an old shipSharp chipping hammers should not be used on either rust or paint, they only mark the metal and make things worse.

    Hammers or scrapers shouldnt be used when there is any possibility of combustible gas or vapor being present.

    Finally wire brush to remove anything left.

  • With an old shipCoat with 2 coats of a primer followed by a coat of undercoating.

    The whole surface is then given a coat of undercoating followed by a coat of gloss or enamel.

    The surface should always be clean and dry.

  • With an old shipEach coat of conventional paint is given at least 24 hours in which to dry before the next coat is applied.

    However, many modern paints will dry in a few hours, some can even be applied on a damp surface, others dont require an undercoat.

  • With an old shipSo, before attempting anything, it is necessary to be sure that the paint is suited to the use to which it is proposed to put it.

  • Various types of paintPRIMERS. Applied to seal an unpainted surface.

    UNDERCOATS. Applied on top of primers to provide a base color and a good key for the top coat.

    TOP COATS. Applied over undercoating to provide a hard wearing surface.

  • Various types of paintHEAT RESISTANT. For use on hot surfaces.

    FIRE-RETARDANT. Has low flame spread characteristics and is for use on exposed surfaces in corridors or stairways, accomodation and service spaces.

    ANTI-CORROSIVE. Primer on the ships bottom.

  • Various types of paintRED LEAD. An oil based primer.

    FLAT PAINT. An oil based undercoating.

    GLOSS or ENAMEL. Top coat for exterior surfaces.

    SEMI-GLOSS. Top coat for interior surfaces.

  • Various types of paintBOOT-TOPINGPainting used on the exterior of the hull area that is out of water when the ship is light and under water when the ship is loaded.

  • Various types of paintTOP-SIDEPaint used on the exterior of the hull above the water line when the ship is loaded.

    *Galvanizing (metallurgical process that is used to coat steel or iron with zinc )