Seamless tubes are a type of welded steel pipe, referring to pipes where the weld seam is parallel to the longitudinal axis of the tube. They are categorized by wall thickness into thin-walled and thick-walled seamless tubes; by shape into round, square, or other-shaped tubes; and by application into general-purpose welded pipes, galvanized welded pipes, oxygen welding pipes, wire conduit, metric welded pipes, roller tubes, deep well pump pipes, automotive tubes, transformer tubes, welding thin-walled tubes, welding non-standard tubes, and spiral-welded pipes.