Tube manufacturing — which processes are suitable for producing ~2 m long seamless metallic tubes (no longitudinal weld seam)?

Introduction / Context:
Seamless tubes lack a longitudinal weld and are therefore produced by plastic deformation routes that create or elongate a hollow from a solid billet or bloom. The question asks which methods can be used to manufacture seamless tubes of about 2 m length—a common industrial size for mechanical and heat-transfer applications.

Given Data / Assumptions:

• Target product: seamless tube (no weld seam).
• Length: roughly 2 m (not limiting for most mill processes).
• Conventional primary processes considered: drawing, extrusion, rolling.

Concept / Approach:

Seamless tubes are commonly produced by: (i) extrusion using a mandrel or piercing plug to form a hollow and push metal through an annular die; and (ii) rolling routes such as Mannesmann rotary piercing followed by elongator/plug/mandrel mills to roll the shell to final size. Cold drawing is typically a secondary sizing/finishing step applied to a previously formed hollow (extruded or pierced) rather than the primary method for making a seamless hollow from solid. Hence, the most appropriate answer is the combination of extrusion and rolling as primary manufacturing routes.

Step-by-Step Solution:

Verification / Alternative check:

Industrial practice across steel and non-ferrous mills uses Mannesmann process (rolling) or direct extrusion to produce seamless hollows, frequently followed by cold finishing.

Why Other Options Are Wrong:

Drawing alone typically requires a starting hollow; rolling or extrusion are the primary “seamless” creators. Selecting only one of extrusion or rolling ignores the commonality of both as valid primary routes.

Common Pitfalls:

Equating tube drawing with initial hollow formation; forgetting that drawing is predominantly a finishing/sizing process for seamless tubes.

Final Answer:

Extrusion and rolling