Spherical flat steel is a kind of special section steel, which is composed of flat web and spherical ball head. Bulb flat steel is mainly used for shipbuilding and bridge building, but with the rapid development of shipbuilding industry in recent years, bulb flat steel has gradually become the special name of marine bulb flat steel, which is the most important type of marine section steel. It is mainly used as the stiffener of ship plate, which is equivalent to human "rib".
The domestic standard of flat bulb steel is GB / t9945-2001 "hot rolled flat bulb steel", and the European standard en10067:1996 "hot rolled flat bulb steel" is adopted non equivalently. The specifications are consistent with the European standard, but the tolerance range of the European standard is modified and the material requirements are added.
China's shipbuilding industry tends to use bulb flat steel in ship form design, while Japan and South Korea tend to use marine angle steel (equilateral angle steel, unequal angle steel and unequal thickness angle steel).
