Steel Tube Types
The type name describes how the tube was made. It is not a grade, not a strength class and not a tolerance schedule. Each page below separates the manufacturing route from the specification fields the drawing actually governs.
Compare the routes
Route, grade and dimensional control are three separate order fields. Resolve the route first, because it constrains which standards and which dimensional outcomes are available.
Welded tube drawn over a mandrel
A welded tube is drawn over a mandrel to bring the outside diameter and wall under closer control and to produce a defined internal surface. ASTM A513 Type 5 is one specific DOM route.
Pierced or extruded from a solid billet
Produced from a solid billet with no longitudinal weld seam. The governing mechanical-tube standard is ASTM A519/A519M; heat-transfer and pressure duties invoke different documents entirely.
Formed from strip or coil and welded along the seam
Formed from steel strip and longitudinally welded. Structural, mechanical and pressure welded tubes sit under different standards with different testing scopes.
Related decisions
Route is the first field. The standard, the grade and the dimensional basis are separate decisions that follow it.
The welded mechanical-tube specification that carries the Type 5 DOM route.
The seamless mechanical-tube specification used for machined components.
How to state which dimension governs acceptance and how it is measured.
