304 Stainless Steel Tubing
Grade 304 stainless steel has a relatively high melting point of 1,400 to 1,450 degrees C and is extremely resistant to wear and corrosion. For these reasons and more, this is a popular material used in the manufacture of steel tubing for a number of environments such as petrochemical, water treatment, pulp and paper, automotive, medical, dental, semiconductor, food processing and aerospace industries among others. Products include fuel lines, architectural supports and even medical implants and instruments as 304 is an easily sanitized surgical grade austenitic steel. Although this alloyed tubing has a higher initial cost than many other options, the elemental structure significantly increases tube longevity, reducing long term expenses such as maintenance and replacements. While 304 stainless steel will eventually need repair or replacement, this material is easily melted down and recycled, further reducing costs and waste.
Originally known as 18/8 stainless steel, in reference to its nominal composition being 18% chromium and 8% nickel, the elemental content of 304 stainless steel is actually variable. While iron and carbon are inherently present, nickel content ranges from 8 to 18 percent while chromium content is between 18 and 20 percent. Low carbon variants known as type 304L have improved weldability though high carbon variants, 304H, perform better at elevated temperatures. The specific alloy selected for a given tubing application is determined by the intended use. The manufacturing process must also be taken into account. Common processes in the production of stainless steel tubing include welding, seamless tubing via extrusion and metal spinning. Seamless tubing is preferred in instances where an edge could be caught and slow or stop production while welded tubes offer a higher degree of precision. The process and particular stainless steel alloy should be carefully considered with regards to the intended use of a 304 stainless steel tube. Further considerations include inner and outer diameters, length, wall thickness, pressure rating, maximum bend radius, temperature range and finishing. As tubing is often a stock shape intended for secondary operations such as roll forming, the machining possibilities of this particular alloy and its variants should also be suited to the needs of the finished product.
