Steel Tubes are more used in Structures; So Outside Diameter is an important factor. The strength of a steel tube depends on the wall thickness of the tube. Hence a tube is specified by the outside diameter and wall thickness. Steel tube are supplied in round sections or square or rectangular tube. Each square or rectangular steel tube has a different mother tube, meaning that they are formed from the original round tube.
The round tube is pass through a forming and a sizing section on the tube mill. During the same process it will continue through a couple of sets of Turks, which will form the round tube to a square or a rectangular steel section. Steel tube used in structural applications would most likely be seam welded while pipe are normally seamless steel.
We, At ferropipe deal in two basic steel tube in accordance with the grades and applications:
Some steel tube are also used in the transport of fluids, even though they are seam welded. These include steel tube for water pipe and welded tube are commonly used in the agricultural industry for manufacturing pivots. Such tube will undergo a process called pressure testing were the tube is sealed at both ends and water is pumped through the tube up to a certain level of pressure. This will quickly indicate if there is a leak or a bad spot in the weld of the circular hollow section tested.
The principal uses for tube are in Heat Exchangers, instrument lines and small interconnections on equipment such as compressors, boilers etc.