Most aluminium street light poles are made from seamless extruded 6063 or 6061 tube that is welded to a base and then heat-treated to the T6 temper. This guide explains which alloy suits which pole, how wind load and weld zones drive the design, and what to specify when you buy the tube, plate and extrusions. Metline supplies these aluminium materials to pole manufacturers and fabricators worldwide; we do not make or install finished poles.
Aluminium has about one third the density of steel, so an aluminium lighting pole is much lighter than a steel pole for the same duty; it also needs no galvanising and does not rust. Those three facts explain why municipalities, highway authorities and private developers specify aluminium for street, car-park, park and coastal lighting.
The weight saving matters twice: once in freight and handling, because a crew can often lift a 6 m aluminium shaft by hand, and again on site, where a lighter pole needs a smaller foundation and a lighter crane. Aluminium forms a thin, self-renewing oxide film, so an uncoated pole keeps its structural section for decades, even near the sea or where de-icing salt is used. Painted or anodised poles hold their finish well because there is no rust creeping under the coating.
Aluminium does have trade-offs. Its modulus of elasticity (about 69 GPa) is one third of steel, so an aluminium shaft must have a larger diameter or thicker wall to limit deflection and vibration. Welding reduces the strength of heat-treated alloys locally, which is why quality pole makers heat-treat the whole shaft after the base is welded on. Good pole design is mostly about managing these two points.
Pole shafts use heat-treatable 6xxx alloys because they extrude well into seamless tube and reach useful strength in the T6 temper. The choice between them is a balance of strength, surface finish and cost.
| Alloy and temper | Where it is used | Why |
|---|---|---|
| 6063-T6 | Most round and tapered street and car-park pole shafts, decorative and fluted poles | Excellent extrusion surface, takes anodising and paint well, adequate strength for most heights; the usual North American shaft alloy |
| 6061-T6 | Taller poles, high-wind sites, mast arms, sign and signal supports | About 30 % higher strength than 6063-T6, so walls can be thinner for the same load |
| 6005A-T6 | Extruded columns and multi-sided sections, common in European practice | Strength between 6063 and 6061 with good extrudability for complex or larger sections |
| 6082-T6 | Heavy-duty columns and brackets to EN specifications | Highest strength of the common 6xxx grades in thick sections |
| 5083 / 5086 plate | Base plates and gussets in marine environments | Non-heat-treatable, keeps strength after welding, very good seawater resistance |
| 6061-T6 plate | Base plates, flanges and anchor plates | Machinable, strong, matches the shaft alloy for welding |
Bases and transformer bases are often aluminium castings (for example A356-T6) made by the pole manufacturer. Metline supplies the wrought materials: tube, extrusions, plate, sheet and bar.
Both alloys are registered with the Aluminum Association and appear in ASTM B221 and EN 573-3. The higher magnesium, silicon and copper in 6061 explain its higher strength; the leaner chemistry of 6063 gives the smoother extruded surface preferred for decorative poles.
| Element | 6063 | 6061 |
|---|---|---|
| Silicon (Si) | 0.20 – 0.60 | 0.40 – 0.80 |
| Iron (Fe) | ≤ 0.35 | ≤ 0.70 |
| Copper (Cu) | ≤ 0.10 | 0.15 – 0.40 |
| Manganese (Mn) | ≤ 0.10 | ≤ 0.15 |
| Magnesium (Mg) | 0.45 – 0.90 | 0.80 – 1.20 |
| Chromium (Cr) | ≤ 0.10 | 0.04 – 0.35 |
| Zinc (Zn) | ≤ 0.10 | ≤ 0.25 |
| Titanium (Ti) | ≤ 0.10 | ≤ 0.15 |
| Others each / total | ≤ 0.05 / 0.15 | ≤ 0.05 / 0.15 |
| Aluminium | Remainder | Remainder |
The figures a structural engineer uses are the specified minimums of the product standard, not typical values. The welded column is the one most often overlooked: if a shaft is welded in T6 and not heat-treated again, the metal next to the weld drops to roughly the strength of the O or T4 condition.
| Material | Typical tensile | Typical yield | Minimum tensile / yield (ASTM B221) | Welded, not re-treated (ADM tensile) |
|---|---|---|---|---|
| 6063-T6 | 241 MPa | 214 MPa | 205 / 170 MPa | about 117 MPa |
| 6061-T6 | 310 MPa | 276 MPa | 260 / 240 MPa | about 165 MPa |
| 6005A-T6 (EN 755-2, wall ≤ 5 mm) | — | — | 270 / 225 MPa | see EN 1999-1-1 |
Typical values from Aluminum Association / ASM data; minimums from ASTM B221 and EN 755-2; welded strengths from the Aluminum Design Manual. Exact limits depend on wall thickness and are shown on the mill certificate.
The governing load on most poles is wind on the luminaire, bracket and shaft. Designers sum the effective projected area (EPA) of the fittings and check bending at the base. Europe uses EN 40-3-1 for loads and EN 40-6 for aluminium columns; North America uses the AASHTO LRFD specification for structural supports for signs, luminaires and traffic signals.
Because aluminium is more flexible than steel, deflection at the top often controls the section rather than strength. A larger diameter is a far more efficient fix than a thicker wall, since stiffness rises with the cube of diameter.
Wind can excite vortex-shedding vibration in tall, slender poles. Weld details at the base and at handhole openings are the usual fatigue hot spots; smooth transitions, reinforced handholes and vibration dampers are standard remedies.
The best practice is to weld the shaft to its base in the T4 or as-extruded condition and then solution heat-treat and age the whole assembly to T6. Welding to AWS D1.2 (North America) or EN 1090-3 (Europe) is normally specified.
Roadside poles in Europe may need classification under EN 12767, which rates how a support behaves in a vehicle impact. Aluminium columns are often chosen because they can be designed to absorb energy or shear away predictably.
Steel anchor bolts, stainless fixings and copper earthing parts must be isolated from the aluminium with washers, sleeves or coatings, and concrete contact below ground should be protected with a bituminous coating.
| Pole shape | How it is usually made | Material Metline can supply |
|---|---|---|
| Straight round | Cut length of seamless extruded tube welded to a base | Seamless 6063 / 6061 round tube |
| Tapered (conical) | Round tube spun or swaged to a taper by the pole maker, then heat-treated | Heavy-wall round tube in T4 or O for forming |
| Square and rectangular | Extruded square tube, often with radiused corners | 6063 / 6061 square and rectangular tube |
| Octagonal and fluted | Custom extrusion die | Profiles extruded to the customer drawing |
| Mast arms and brackets | Bent tube or extruded sections | Smaller-diameter tube, bar and profiles |
| Base plates, door covers | Plate and sheet cut and machined | 6061-T6, 5083 plate; 5052 sheet |
Pole types range from short bollards and 3 – 4 m garden and park columns, through 6 – 12 m street and car-park poles, to traffic signal and sign supports. Solar and smart poles add a battery or electronics compartment and extra cable entries, so the shaft must be checked for the larger openings and the added weight and wind area of panels, cameras or antennas.
The table lists sizes commonly used for pole shafts. Weight is calculated from geometry using 2.70 g/cm³; actual weight varies slightly within the standard tolerances. Use the round tube weight calculator for other sizes.
| Outside diameter (mm) | Wall (mm) | Mass (kg/m) | Mass of 6 m length (kg) |
|---|---|---|---|
| 76.2 | 3.00 | 1.86 | 11.2 |
| 101.6 | 3.20 | 2.67 | 16.0 |
| 114.3 | 3.20 | 3.02 | 18.1 |
| 127.0 | 4.00 | 4.17 | 25.0 |
| 152.4 | 4.80 | 6.01 | 36.1 |
| 165.0 | 4.00 | 5.46 | 32.8 |
| 165.0 | 6.00 | 8.09 | 48.6 |
| 203.2 | 4.80 | 8.08 | 48.5 |
| 203.2 | 6.35 | 10.60 | 63.6 |
| 254.0 | 6.35 | 13.34 | 80.0 |
Mill-finish aluminium weathers to a uniform matt grey and needs no coating for protection. Most specifiers still choose a finish for appearance and to keep the surface clean.
6063-T6 is the usual choice for standard street and car-park poles because it extrudes with a better surface and is easier to finish. 6061-T6 is about 30 % stronger and is chosen for taller poles, high wind zones, mast arms and sign supports where a thinner wall saves weight.
Yes, locally. The heat-affected zone of a T6 alloy drops to roughly half its strength. Good practice is to weld the base on first and then heat-treat the whole pole back to T6, or to design the base using the reduced welded strength.
Aluminium does not rust, so the structural section is preserved for decades with little maintenance. Service life depends mostly on design against fatigue, protection of the buried section, isolation from steel and copper, and the condition of the finish.
In Europe, EN 40-6 covers aluminium lighting columns, with loads and verification in EN 40-3. In North America, the AASHTO LRFD specification for structural supports for signs, luminaires and traffic signals applies, with tube to ASTM B221 or B429 and welding to AWS D1.2.
No. Metline supplies the aluminium materials, such as seamless tube, extrusions, plate, sheet and bar, cut to length or machined to drawing. Pole manufacturers carry out tapering, welding, heat treatment, finishing and assembly.
A 114.3 mm OD × 3.2 mm wall tube weighs about 3.0 kg per metre, so a 6 m shaft is roughly 18 kg before the base and bracket. A 152.4 × 4.8 mm tube is about 6.0 kg/m.
Tell us the alloy, sizes, quantities and destination. We will reply with availability, certification and a delivered price.
