Commission Regulation (EEC) No 3813/88 of 7 December 1988 re-establishing the levying of the customs duties applicable to nuts of iron or steel falling within CN codes 7318 16 30, 7318 16 91 and 7318 16 99 originating in Singapore to which the preferential tariff arrangements set out in Council Regulation (EEC) No 3635/87 apply