28/01/2025
MATERIALS FOR TANKER CONSTRUCTION. Mild steel is used throughout the structure, but higher tensile steels may also be introduced in the more highly stressed regions of the larger vessels.
Mild steel
As with dry cargo ships it is a requirement that Grade B, D, and E steels be used for the heavier plating of the main hull strength members where the greatest stresses arise in tankers. Grade E plates, which we have equated with the ‘crack arrester strake’ concept, will be seen to be required over the midship region in ships exceeding 250 meters in length and are also required as shown in Table 1.
Table 1. Use of Grade E steel in tankers
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Location (Stringer plate, sheerstrake, rounded gunwale) Thickness (Greater than 15 mm)
Location (Bilge strake, deck strake in way of longitudinal bulkhead) Thickness (Greater than 25 mm)
Location (Main deck plating, bottom plating, keel, upper strake of longitudinal bulkhead) Thickness) (Greater than 40 mm)
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Higher tensile steel
Higher tensile steels are often used for the deck and bottom regions of the larger tankers, Grades DH and EH being used for the heavier plating.
The use of higher tensile steel leads to a reduction in the scantlings of these structural items with advantages both for the shipbuilder and owner. There is some concern that the thinner material may lead to problems if corrosion occurs, and that the thinner plate may also lead to additional fatigue problems due to excess movement of the structure under the forces encountered. The extent of this plating and section material is indicated in Figure.
Figure. Double-hull oil tanker.
