Hollow sections

Aluminium Round Tube

Aluminium round tube is a hollow circular section described by outside diameter (OD) and wall thickness, made by extrusion, by cold drawing or by seam welding of strip. The route matters as much as the grade: structural porthole tube, seamless tube and welded tube suit different pressures, tolerances and budgets. Metline supplies round tube in all common grades and routes, cut to length and certified, to customers worldwide.

By Metline Technical Team · Updated 17 October 2026

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Extruded aluminium round tubes in several diameters

Routes: Porthole, seamless, drawn, welded
Main grades: 6061, 6063, 6082, 3003
OD range: about 3 – 500 mm
Standards: ASTM B210 · B221 · B241 · EN 754 / 755

Overview

What is aluminium round tube?

Round tube is the most efficient aluminium section for torsion, internal pressure and bending in any direction, which is why it appears in everything from bicycle frames and handrails to heat exchangers, hydraulic lines and aircraft structures. It is specified by OD and wall thickness (or OD and ID for thick tube), unlike pipe, which is sized by nominal pipe size and schedule.

Aluminium tube is lighter than steel tube of the same size by about two thirds, does not rust, and can be anodised or powder coated. The trade-off is a lower modulus (about 69 GPa against 200 GPa for steel), so for the same stiffness an aluminium tube is usually made larger in diameter rather than thicker in wall.

If you are sizing pipe for fluid service by schedule (SCH 40, SCH 80), see the aluminium pipe page. This page covers tube sized by actual OD and wall.

Manufacturing

Porthole, seamless, drawn and welded tube compared

Route	How it is made	Strengths	Watch-outs	Main standards
Porthole (structural) extruded	Billet splits around a bridge die and re-welds inside the die	Low cost, wide size range, short lead times	Contains longitudinal extrusion welds; not for high-pressure or critical service	ASTM B221, EN 755-8
Seamless extruded	Hollow or pierced billet extruded over a mandrel	No seam welds; suits pressure and critical parts	Higher cost; heavier minimum wall	ASTM B241, EN 755-7
Seamless cold drawn	Extruded tube drawn over a mandrel or plug	Tight OD and wall tolerances, thin walls, smooth bore	Smaller sizes; extra cost per kg	ASTM B210, B483, EN 754-7
Welded (HF or laser)	Strip roll-formed and welded along the seam	Very thin walls, long lengths, lowest cost in high volume	Lower-strength grades mostly; weld bead on ID	ASTM B313, EN 1592

A useful rule: if the tube carries internal pressure, will be bent hard, or is called up by an aerospace or pressure code, ask for seamless. For frames, furniture, handrails, scaffolding-type structures and general fabrication, porthole tube is normally fine and noticeably cheaper.

Grades

Round tube grades and typical properties

Grade and temper	Typical tensile	Typical yield	Character	Typical uses
3003-H14	150 MPa	145 MPa	Formable, corrosion resistant	Heat exchangers, fuel and refrigerant lines
5052-H32	228 MPa	193 MPa	Good marine resistance, bendable	Marine rails, fuel lines, instrument tube
6063-T5	186 MPa	145 MPa	Best surface, anodises well	Architectural, furniture, curtain rails
6063-T6	241 MPa	214 MPa	Smooth finish, moderate strength	Handrails, frames, irrigation
6061-T6	310 MPa	276 MPa	Strong, weldable, machinable	Structures, bicycle and vehicle frames, hydraulic tube
6082-T6	about 310 MPa (min. 290 – 310)	about 260 MPa (min. 250 – 260)	European structural standard	Structures, trailers, scaffolding
2024-T3	483 MPa	345 MPa	High strength and fatigue	Aerospace tube, high-load parts
7075-T6	572 MPa	503 MPa	Highest strength	Sports goods, aerospace, tent poles

Typical values from Aluminum Association and ASM data; 6082 values are EN 755-2 minimums, which depend on wall thickness. Governing values are the specified minimums on the mill certificate.

Supply range

Round tube sizes and weight per metre

Supply range

Outside diameter: about 3 – 500 mm; drawn precision tube typically 3 – 150 mm
Wall thickness: about 0.3 – 50 mm depending on route and OD
Imperial sizes: 1/8 in to 12 in OD, walls such as 0.035, 0.049, 0.065, 0.125, 0.250 in
Lengths: 3 m, 5.8 m, 6 m, 12 ft and 20 ft; coils for small welded or drawn tube
Finish: Mill finish, anodised, powder coated or polished on request
Processing: Cut to length, deburring, bending and end forming on request

Weight in kg/m = 0.0084823 × (OD − wall) × wall, with dimensions in mm and density 2.70 g/cm³. Use the tube weight calculator for other sizes.

OD (mm)	Wall (mm)	ID (mm)	kg per metre	kg per 6 m
12	1	10	0.093	0.56
16	1.5	13	0.184	1.11
20	2	16	0.305	1.83
25	2	21	0.390	2.34
25.4	1.65	22.1	0.332	1.99
32	2	28	0.509	3.05
38.1	3.18	31.74	0.942	5.65
40	3	34	0.942	5.65
50	3	44	1.196	7.18
50.8	3.18	44.44	1.284	7.71
60	4	52	1.900	11.40
76.2	6.35	63.5	3.762	22.57
80	5	70	3.181	19.09
100	5	90	4.029	24.17
120	10	100	9.331	55.98
150	10	130	11.875	71.25
200	15	170	23.538	141.23

Tolerances & inspection

Tolerances, ovality and testing

Round tube tolerances cover mean OD, OD at any point (which controls ovality), wall thickness, straightness and length. Extruded tube follows EN 755-7/-8 or ASTM B221/B241 tables; drawn tube to EN 754-7 or ASTM B210/B483 is several times tighter, which matters for hydraulic cylinders, telescopic assemblies and push-fit joints.

Inspection options

Dimensional: OD, ID, wall and ovality by micrometer and bore gauge; eccentricity checked on seamless tube
Eddy current: Through-coil eddy current testing to detect seam defects and pits on thin tube
Pressure: Hydrostatic or pneumatic leak tests for heat-exchanger and fluid tube
Mechanical: Tensile, flattening and expansion (flare) tests per the order standard
Certification: EN 10204 3.1 certificate with chemistry, mechanical results and test records

Working with tube

Bending, joining and finishing round tube

Bending

Mandrel bending gives the tightest radii without wrinkling. Annealed (O) or T4 tube bends much tighter than T6; bend in T4 and age afterwards for strong formed parts.

Welding

6061, 6063, 6082, 3003 and 5052 weld well by TIG or MIG. The heat-affected zone of 6xxx tube loses part of its T6 strength.

Mechanical joints

Swaging, flaring, crimping and push-in connectors suit drawn tube with tight OD tolerance.

Brazing

3003 tube is widely brazed in heat exchangers with 4xxx filler and flux or vacuum processes.

Anodising and coating

6063 gives the best decorative anodised finish; 6061 and 6082 anodise well for protective coatings.

Machining

Thin-wall tube needs soft jaws or expanding mandrels to avoid ovality during turning.

Applications

Where aluminium round tube is used

Structures and frames: trusses, stage rigging, scaffolding, greenhouses, solar mounting
Transport: bicycle and motorcycle frames, roof racks, truck and trailer components, aircraft tube
Heat transfer: condenser, radiator and evaporator tube, refrigerant lines
Fluid power: pneumatic and hydraulic cylinder barrels, fuel and lubrication lines
Architecture: handrails, balustrades, sunshades, curtain-wall elements
Consumer goods: furniture, tent poles, ladders, sports equipment, medical aids

Ordering

How to order round tube from Metline

SpecifyGrade and temper, OD and wall (or OD and ID), production route, length, quantity, governing standard and any pressure or eddy-current testing.
QuoteWe confirm alloy, temper, tolerances, certification, packing and delivery terms (EXW, FOB, CIF or DAP) for your destination.
ProcessTubes are cut to length, deburred, checked for OD, wall and straightness, and capped or wrapped to protect the bore and surface.
DocumentEach delivery carries a mill test certificate to EN 10204 3.1 with the cast analysis and mechanical results; third-party inspection can be arranged on request.
ShipBundled, interleaved or crated for export and shipped by sea or air on EXW, FOB, CIF or DAP terms.

Sources

References and standards

ASTM B210 – Standard Specification for Aluminum and Aluminum-Alloy Drawn Seamless Tubes
ASTM B241 – Standard Specification for Aluminum and Aluminum-Alloy Seamless Pipe and Seamless Extruded Tube
ASTM B221 – Standard Specification for Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes
EN 754-7 / EN 755-7 / EN 755-8 – Seamless and porthole tubes: tolerances
The Aluminum Association – International Alloy Designations and Chemical Composition Limits for Wrought Aluminum (Teal Sheets)

FAQ

Aluminium (aluminum) round tube: frequently asked questions

What is the difference between aluminium tube and pipe?

Tube is specified by its actual outside diameter and wall thickness and is used mainly for structures and mechanical parts. Pipe is specified by nominal pipe size and schedule (for example 2 in SCH 40) and is used mainly for fluid systems.

Is extruded aluminium tube seamless?

Not always. Most structural tube is made on porthole dies, which leave longitudinal extrusion welds. Seamless tube is extruded over a mandrel from a hollow or pierced billet, or drawn from such tube. Specify seamless when the tube carries pressure or is safety-critical.

Which aluminium tube grade is best for bending?

3003, 5052 and 6063 bend most easily. For a strong bent part, bend 6061 in O or T4 temper and then age it to T6, or use mandrel bending with generous radii in T6.

How do I calculate the weight of aluminium tube?

Weight (kg/m) = 0.0084823 × (OD − wall) × wall, with dimensions in millimetres. A 50 × 3 mm tube weighs about 1.20 kg per metre.

Can aluminium round tube be anodised?

Yes. 6063 gives the brightest, most uniform decorative finish; 6061 and 6082 are widely anodised for protection and hard coating. Tell us the finish when ordering so we can select the right grade and surface quality.

Do you ship aluminium tube worldwide?

Yes. Round tube is supplied in mill or cut lengths with mill certificates and export packing, by sea or air.