Seamless tubes are long steel products with a hollow cross-section and no weld seams. Globally, there are over 5,100 manufacturing facilities operated by more than 1,850 companies across 110 countries, with over 260 of these facilities currently in operation under 170 companies in 44 different nations. These pipes come in various specifications and are produced using different methods such as hot rolling, cold drawing, and thermal expansion. The general specification ranges from 6 to 1,240 mm in diameter and 1 to 200 mm in wall thickness.
There are several standards that define the use and material composition of seamless tubes. For example, GB/T 8162-1999 covers structural seamless tubes, commonly used in general mechanical and structural applications. Materials like carbon steels (20#, 45#) and alloy steels (Q345, 20Cr, 40Cr, 20CrMo, 30-35CrMo, 42CrMo) are frequently used.
GB/T 8163-1999 refers to seamless tubes for fluid transportation, often applied in engineering and large equipment pipelines. Common materials include 20# and Q345. For low and medium pressure boilers, GB/3087-1999 specifies tubes made from 10#, 20# steels.
High-pressure boiler applications follow GB5310-1995, which uses materials like 20G, 12Cr1MoVG, and 15CrMoG for high-temperature and high-pressure environments. Similarly, GB5312-1999 is designed for marine applications, with materials such as 360, 410, and 460 grades used in ship boilers.
For high-pressure chemical equipment, GB1479-2000 defines materials like 20#, 16Mn, 12CrMo, and 12Cr2Mo. In petroleum refining, GB9948-1988 outlines materials such as 20#, 12CrMo, 1Cr5Mo, and 1Cr19Ni11Nb for use in heat exchangers and pipelines.
Other standards include GB18248-2000 for gas and hydraulic cylinders, GB/T17396-1998 for coal mine hydraulic supports, and GB3093-1986 for diesel engine fuel injection systems. Precision tubes are covered by GB/T3639-1983 and GB/T8713-1988, which require high dimensional accuracy and smooth surfaces.
Stainless steel seamless tubes, defined by GB13296-1991, are used in corrosive and high-temperature environments, with materials like 0Cr18Ni9 and 1Cr18Ni9Ti. GB/T14975-1994 covers thick-walled structural tubes, while GB/T14976-1994 focuses on precision tubes for conveying corrosive media.
Finally, YB/T5035-1993 is used for automotive axle bushings, with materials like 45#, 45Mn2, and 40Cr. When distinguishing seamless tubes, it's essential to consider their intended use, specifications, and material properties to ensure proper application.
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