RINA Grade B bulb flat steel is common strength shipbuilding bulb flat.RINA Grade B shipbuilding bulb flat is mainly used in shipbuilding and bridge-building field.In morden shipbuilding industry,the main hull of larger vessels and formal ships are constructed by these shipbuilding bulb flats RINA B.Bulb flat build the ship bones and then use the shipbuilding steel plates to fill in the bones with the same thickness.Some shipyards use the angle steels to build ship bones also,such as Unequal led and unequal thickness angle steel,Unequal Angle steel(Unequal-leg angle steel) or Equal angle steel.