Discharge manifolds
Pipes running from each compartment's bottom valve to the API couplers or hose connections. Usually 3 in or 4 in nominal size.
Tank-vehicle tube guide
6063 Aluminium Tube for Oil and Fuel Tankers
Road tankers that carry petrol, diesel, lubricants and other oil products use aluminium tube for discharge manifolds, vapour-recovery lines, drains, breather fittings and body hardware. 6063 in T4, T5 or T6 temper is the usual choice for these parts because it extrudes into accurate, smooth-bored tube, welds well, resists fuel and weather and does not rust. This guide covers its properties, sizes and what to check before ordering.
- Alloy
- 6063 (EN AW-6063)
- Tempers
- T4, T5, T6
- OD range
- About 6 – 450 mm
- Standards
- ASTM B221 / B241 · EN 755
Where tube is used on an oil or fuel tanker
A fuel tanker body is a set of welded aluminium compartments, each with its own bottom valve, discharge pipe and vapour connection. The shell itself is normally rolled from 5xxx plate such as 5083, 5182 or 5454, which keep their strength after welding. The pipework and secondary structure around the shell is where 6063 tube is used.
Vapour-recovery lines
Tubes that collect vapour from each compartment during loading and return it to the terminal. Low pressure, but they must be leak-tight and conductive.
Breather and vent fittings
Bodies for breather valves, flame-arrester housings and vent pipes, where a light, non-rusting metal is preferred.
Drains and overflow pipes
Small-diameter tube carrying rain and spills away from manholes and walkways.
Body hardware
Handrails, folding guardrails, ladders, hose trays and cabinet frames along the top and sides of the tank.
Light frames
Brackets, stiffeners and support frames where loads are moderate and low weight increases payload.
Using aluminium for these parts keeps the whole vehicle in one material family, avoids galvanic problems at welded joints with the shell and removes the rust that steel pipework sheds into fuel. Each kilogram saved on fittings is a kilogram of extra legal payload on every trip.
6063 chemical composition (wt %)
| Element | Limit | Note |
|---|---|---|
| Silicon (Si) | 0.20 – 0.60 | Combines with Mg to form Mg2Si |
| Iron (Fe) | ≤ 0.35 | Low iron gives a bright, smooth surface |
| Copper (Cu) | ≤ 0.10 | Kept low for corrosion resistance |
| Manganese (Mn) | ≤ 0.10 | |
| Magnesium (Mg) | 0.45 – 0.90 | Main strengthening element |
| Chromium (Cr) | ≤ 0.10 | |
| Zinc (Zn) | ≤ 0.10 | |
| Titanium (Ti) | ≤ 0.10 | Grain refiner |
| Others, each / total | ≤ 0.05 / 0.15 | |
| Aluminium (Al) | Remainder |
These are the Aluminum Association limits used by ASTM B221, ASTM B241 and EN 573-3. The low copper content is one reason 6063 resists fuel, condensate and road salt better than copper-bearing alloys such as 2024 or even 6061.
Mechanical properties of 6063 tube by temper
Minimum values below are from ASTM B221 for extruded tube; EN 755-2 values are similar. Design to the minimums. Welding locally softens T5 and T6 tube to roughly T4-level strength near the weld, so welded pipework is sized on the as-welded strength.
| Temper | Wall thickness | Tensile min | Yield min | Elongation min (50 mm) |
|---|---|---|---|---|
| T4 | ≤ 12.5 mm | 130 MPa (19 ksi) | 70 MPa (10 ksi) | 14 % |
| T5 | ≤ 12.5 mm | 150 MPa (22 ksi) | 110 MPa (16 ksi) | 8 % |
| T6 | ≤ 3.2 mm | 205 MPa (30 ksi) | 170 MPa (25 ksi) | 8 % |
| T6 | 3.2 – 25 mm | 205 MPa (30 ksi) | 170 MPa (25 ksi) | 10 % |
Physical properties
- Density
- 2.70 g/cm³, about one-third of steel
- Thermal conductivity
- About 200 W/m·K (T6)
- Electrical conductivity
- About 53 – 55 % IACS, which helps bond and earth the pipework
- Melting range
- About 615 – 655 °C
T4, T5 or T6 for tanker parts?
T4 for bending
Softest of the three. Choose it for manifolds with tight bends or flared ends; the tube can be aged to T6 after forming if strength is needed.
T5 for general pipe
Air-cooled from the press and aged. Adequate for vapour lines, drains and body rails at the lowest cost.
T6 for load
Peak strength. Choose it for handrails, guardrails, ladders and frames that carry people or equipment, and for straight discharge pipe.
Tube sizes and weights
Typical supply range
- Outside diameter
- About 6 – 450 mm
- Wall thickness
- About 0.5 – 25 mm, depending on diameter
- Length
- Mill lengths, usually 6 m, or cut to length
- Types
- Extruded (porthole or seamless), drawn seamless, and pipe to ANSI schedule sizes
- Finish
- Mill finish, anodised or powder coated
Mass per metre = π × (OD − wall) × wall × 2.70 / 1000, with dimensions in millimetres. Reference values for common tanker sizes:
| OD (mm) | Wall (mm) | Mass (kg/m) |
|---|---|---|
| 50.8 | 3 | 1.216 |
| 63.5 | 3 | 1.540 |
| 76.2 | 3 | 1.863 |
| 88.9 | 3.5 | 2.535 |
| 101.6 | 3.5 | 2.912 |
| 101.6 | 5 | 4.097 |
| 114.3 | 4 | 3.742 |
| 127 | 4 | 4.173 |
| 152.4 | 5 | 6.251 |
Welding, bending and finishing
- Welding: TIG and MIG with ER4043 (lower crack sensitivity, smoother bead) or ER5356 (higher as-welded strength, better colour match after anodising). Clean off oxide and oil right before welding.
- Pressure testing: leak-test welded manifolds and vapour lines with air or a suitable test medium as the tank design requires.
- Bending: rotary-draw bending with a mandrel gives the best result on thin-wall tube. Bend T4 or T5 where radii are tight.
- Electrical continuity: fuel tankers must be bonded to dissipate static. Aluminium pipework conducts well, but check continuity across any rubber or plastic hose sections.
- Finishing: anodising, polishing or powder coating for visible body hardware; mill finish for internal pipework.
- Corrosion: 6063 resists fuels, oils and the atmosphere well. Avoid strong alkalis and acids, and isolate it from steel fasteners with washers or sleeves.
Standards that apply
| Area | Standard | What it covers |
|---|---|---|
| Extruded tube | ASTM B221, EN 755-2/-8 | Properties and tolerances of extruded tube |
| Seamless pipe and tube | ASTM B241, ASTM B210 (drawn) | Seamless extruded and drawn tube for pressure applications |
| Chemistry | EN 573-3, Aluminum Association registration | Composition limits |
| Tank design | EN 13094, ADR | Metallic tanks for dangerous goods with low working pressure; vehicle approval |
| Certificates | EN 10204 3.1 | Inspection document for each lot |
Tank design approval covers the whole vehicle; the tube supplier provides the material certificates the body builder needs for that approval file.
What to check when buying tanker tube
- SpecificationName the alloy, temper and standard, for example "6063-T6 to ASTM B221" or "EN AW-6063 T6 to EN 755-2".
- DimensionsGive OD, wall and length; state whether OD or ID is critical for coupler fit.
- Seamless or portholeFor pressure lines, ask for seamless tube; porthole-die tube has longitudinal weld seams that are fine for rails and drains.
- InspectionCheck surface, straightness and ends on arrival; ask for hardness or tensile results on the certificate.
- PackingSpecify bundles with end caps or wooden cases so tube ends and finished surfaces arrive undamaged.
References and standards
- ASTM B221 – Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes
- ASTM B241/B241M – Aluminum and Aluminum-Alloy Seamless Pipe and Seamless Extruded Tube
- EN 755-2 – Extruded rod/bar, tube and profiles: mechanical properties
- EN 13094 – Tanks for the transport of dangerous goods: metallic tanks with a working pressure not exceeding 0.5 bar
- UNECE – ADR, European Agreement concerning the International Carriage of Dangerous Goods by Road
6063 tanker tube: FAQ
Why use aluminium tube instead of steel on a fuel tanker?
It is about one-third the weight, does not rust into the product, welds to an aluminium tank without galvanic problems and conducts static charge well.
Is 6063 strong enough for tanker discharge pipe?
Yes for typical gravity and pump discharge pressures. 6063-T6 has a minimum yield strength of 170 MPa before welding; designers size the wall on the lower as-welded strength.
Should I use 6063 or 6061 aluminum tube?
6061-T6 is about 40 % stronger and suits highly stressed frames. 6063 is easier to bend, has a better surface and lower cost, so it is preferred for piping, rails and trim.
Can 6063 tube be anodised?
Yes. It gives one of the most even anodised finishes of any aluminium alloy, which suits visible handrails and ladders.
What sizes are typical for tanker discharge lines?
Most bottom-loading systems use 3 in or 4 in nominal lines, so tube with an OD around 76 – 115 mm is common. Match the size to your valve and coupler.
Building or refurbishing tankers?
Tell us the tube sizes, tempers and quantities, and Metline will quote with mill certificates and export packing.
