Description / Application / Shipment / Storage
Basically, there are three types of steel commonly carried by sea in appreciably quantities: sheets, roiled sections and small section material, rods and wire.
Steel sheet is mainly carried in the form of coils, but smaller quantities are frequently carried in packs. It is produced by heating and rolling steel ingots through reduction mills. As the thickness of the steel is reduced, its length increases and, for convenience in handling the long narrow sheet is rolled into a coil. The coil is then tightly strapped through the core and around the circumference and made ready for transporting to the loading port. These coils are described as hot rolled coils or raw steel and they will require further processing in the country of destination.
Instead of being prepared for shipment as hot rolled coils, the steel may be further processed in the country of manufacture. In the first place, it is passed through baths filled with a weak acid solution to remove rust and scale. This process is described as pickling. The sheet is then washed, dried, oiled and re-coiled before being passed on to the cold reduction mill, where it will be cold rolled under tension, the end result being a product of better temper and improved finish.
Cold rolled sheet may be further processed by dipping the sheet into a bath of zinc to produce coils of galvanised steel sheeting. Alternatively, tin plate may be produced by covering one or both surfaces of the sheet with a thin layer of tin.
Cold rolled steel, galvanised steel sheet and tin plate are of courser very much more valuable than hot rolled sheet. Coils of cold rolled sheet, galvanised steel sheeting and tin plate will be strapped in the same way as hot rolled coils and in addition, before leaving the factory for transportation to the port of loading, will normally be wrapped in protective/reinforced paper and then covered with fine gauge steel sheeting which is itself secured in place with metal strapping.
On occasions cold rolled sheets, galvanised sheets and tin plate may be carried in packs instead of coils. The bundle of cold rolled sheets forming a pack is secured with steel strapping. It is then usually completely wrapped in protective/reinforced paper and covered with a metal envelope. The package will then be secured by metals straps to wooden skids.
Rolled sections or construction steel are usually fairly massive sections, in the form of H, I or U (channel) beams. They are produced by passing the steel ingots through a series of rollers.
Small section material, rods and wire may be composed of special steel alloys, or may consist of steel that has been given a special finish at the factory. Small section material is usually destined for use in the manufacture of machine tools, of components for electrical machinery, or of steel furniture. Other uses to which small section material is put are the construction of ladders for fire escapes, of racks in factories or warehouses, of railings and of numerous other appliances or fittings where a quality finish may be required. Small section material is shipped in bundles and may or may not be wrapped.
Reinforcing bars may be mentioned here: they are often referred to as ‘rounds’ or ‘concrete iron’ or ‘deformed reinforcing bars’ or just ‘re-bars’. The use of the word ‘deformed’ means that the bars have ridged in various patterns introduced into their surface during production. These ridges improve the bond of the bar with the concrete and thus increase the constructional strength of the finished structure.
Wire rod is largely produced by drawing larger bars through dies. It is prepared for shipment at the factory by being rolled into coils and usually four or five coils are then strapped together to form a unitised coil bundle.
In the country of destination the wire will be cold drawn through dies so that the gauge is reduced and the wire elongated and polished to form what is called bright basic wire. Wire rod is used in the manufacture if numerous goods such as nails, wire mesh, galvanised wire and a large quantity of this wire is chromed and used in the manufacture of supermarket shopping baskets and trolleys.
- Wet damage/corrosion
- Mechanical damage