A medium profile material mainly used in shipbuilding and bridge building fields
Bulb flat steel is a medium-section bar mainly used in the fields of shipbuilding and bridge building. Marine ball flat steel is an auxiliary medium-section bar for shipbuilding. In recent years, with the rapid development of the shipbuilding industry, the demand for marine flat steel is strong. Generally, the main hulls of larger ships and regular ships are mostly made of marine spherical flat steel, and the spherical flat steel with the same thickness and material as the connected plates is used as the frame material (also called ribs or keels).
Ball flat steel is a type of special steel, which is composed of a flat web and a spherical ball head. It is an asymmetric steel. Bulb flat steel is mainly used in shipbuilding and bridge building. However, with the rapid development of the shipbuilding industry in recent years, bulb flat steel has gradually become the specific name of marine bulb flat steel. It is the most important type of marine steel and is mainly used as a ship plate. The use of stiffeners is equivalent to human “ribs”.
China’s domestic standard for flat ball steel is GB/T9945-2001 “Hot-rolled flat ball steel”, which is not equivalent to the European standard EN10067:1996 “Hot-rolled flat ball steel”. The specifications are consistent with the European standard, but are modified. The tolerance range of the European standard has been expanded, and regulations such as materials have been added.
China’s shipbuilding industry tends to use bulb flat steel in ship design, while Japan and South Korea tend to use marine angle steel (equilateral angle steel, unequal angle steel and unequal angle steel).
The specifications of flat bulb steel are generally divided according to the nominal width. The minimum specification is 8# (that is, the nominal width is 80mm), and the maximum specification is 43# (the maximum nominal width is 430mm). Each specification has 2 to 5 different thicknesses.
The material of flat bulb steel corresponds to the ship plate, and is divided into general strength (Grade A, Grade B and D, etc.) and high strength (AH32, AH36, DH32 and DH36, etc.). Ship plates certified by different classification societies need to be used together. Flat bulb steel approved by different classification societies.
