Drawn seamless tube
Extruded hollow is cold-drawn over a mandrel through a die to final size. This gives tight OD and wall tolerances, a smooth bore and a bright finish. Required for hydraulic and fuel lines (AMS 4081, 4083).
Drawn seamless, hydraulic and extruded tube
6061 Aircraft Aluminium Tube & Pipe
6061 aircraft tube is drawn seamless or extruded 6061 tubing made and certified to aerospace specifications such as AMS 4079, AMS 4080, AMS 4081, AMS 4082 and AMS 4083. It is the standard aluminium tube for aircraft hydraulic and fuel lines, conduits, structural struts and airframe tubing that must bend, flare and weld well. Metline supplies 6061 tube in O, T4 and T6 tempers, round, square and rectangular, to customers worldwide.
- Alloy
- 6061 (Al-Mg-Si-Cu)
- Tempers
- O, T4, T6, T6511
- Types
- Drawn seamless, hydraulic, extruded
- Specs
- AMS 4079 – 4083 · ASTM B210
What is 6061 aircraft tube?
Not every 6061 tube qualifies for aircraft use. "Aircraft" or "aerospace" tube is 6061 that is drawn or extruded, heat-treated, tested and certified to an aerospace material specification, with traceability from the cast to the finished length. The alloy is standard 6061; the specification, the tighter tolerances and the extra tests are what make it flight material.
6061 became the default aluminium tube in aircraft because it combines three things that hydraulic and structural tubing needs: it bends and flares without cracking in T4 or T6, it resists corrosion well without cladding, and it welds with common TIG and MIG procedures. Seamless drawn 6061-T6 tube is used for medium-pressure hydraulic return and pressure lines, fuel and oil lines, and pneumatic systems. Thicker-walled drawn and extruded tube becomes control rods, struts, frames and seat and cargo structures.
Higher-pressure hydraulic lines on large aircraft often use titanium or stainless steel, and 2024-T3 tube is chosen where higher strength is needed. 6061 remains the tube of choice where pressure and temperature allow it, because it is easier to form and install and costs less.
Aerospace specifications for 6061 tube
The specification on the drawing sets the manufacturing route, temper and tests. These are the documents most often called up for 6061 tubing:
| Specification | Product | Temper | Typical use |
|---|---|---|---|
| SAE AMS 4079 | Drawn seamless round tube, close tolerance | O | Lines to be formed and heat-treated by the user |
| SAE AMS 4080 | Drawn seamless tube | O | Conduits and low-pressure fluid lines; wall 0.46 – 12.70 mm |
| SAE AMS 4081 | Drawn seamless hydraulic tube | T4 | Hydraulic lines needing maximum formability for flaring |
| SAE AMS 4082 | Drawn seamless tube | T6 | Brackets, conduits, low-pressure lines; wall 0.64 – 12.70 mm |
| SAE AMS 4083 | Drawn seamless hydraulic tube | T6 | Hydraulic pressure and return lines; wall 0.64 – 12.70 mm |
| SAE AMS 4150 | Extruded bar, rod, profiles and tube | T6 | Structural tube and extruded shapes |
| SAE AMS 4173 | Extruded tube and profiles, stress-relieved | T6510 / T6511 | Machined tubular parts needing straightness and stability |
| AMS-T-7081 | Seamless drawn hydraulic tube (former MIL-T-7081) | T4, T6 | Legacy drawings for hydraulic lines |
| ASTM B210 / B210M | Drawn seamless tube, general | O, T4, T6 | Commercial and industrial equivalent of drawn tube |
| ASTM B221 / B241 / B429 | Extruded tube; seamless pipe; structural pipe and tube | T4, T6, T6511 | Commercial extruded tube and pipe |
Former federal specifications such as WW-T-700/6 (6061 drawn tube) have been replaced by AMS or ASTM documents. If an old drawing calls for them, tell us and we will propose the current equivalent for your approval.
6061 chemical composition (wt %)
All 6061 tube specifications use the registered Aluminum Association composition. The mill certificate reports the actual analysis of each cast.
| Element | Minimum | Maximum | Role in the alloy |
|---|---|---|---|
| Silicon (Si) | 0.40 | 0.80 | Forms the strengthening Mg2Si phase with magnesium |
| Iron (Fe) | — | 0.70 | Impurity; held low for toughness and surface quality |
| Copper (Cu) | 0.15 | 0.40 | Adds strength; a small penalty in corrosion resistance |
| Manganese (Mn) | — | 0.15 | Grain structure control |
| Magnesium (Mg) | 0.80 | 1.20 | Main strengthening element with silicon |
| Chromium (Cr) | 0.04 | 0.35 | Limits recrystallisation, improves stress-corrosion resistance |
| Zinc (Zn) | — | 0.25 | Impurity |
| Titanium (Ti) | — | 0.15 | Grain refiner |
| Others, each / total | — | 0.05 / 0.15 | |
| Aluminium (Al) | Remainder | About 95.8 – 98.6 % |
Mechanical properties of 6061 tube
Drawn tube reaches slightly higher guaranteed strength than extruded tube in the same temper, because cold drawing refines the structure and the ASTM and AMS tables for drawn tube set higher minimums. The values below are minimums (or maximums for O temper) from ASTM B210 and B221 and the matching AMS documents; typical values are given for comparison.
| Product and temper | Tensile strength | Yield strength (0.2 %) | Elongation (min, in 2 in / 50 mm) |
|---|---|---|---|
| Drawn tube, O (max) | ≤ 150 MPa / 22 ksi | ≤ 97 MPa / 14 ksi | 15 – 20 % (wall dependent) |
| Drawn tube, T4 (min) | 205 MPa / 30 ksi | 110 MPa / 16 ksi | 14 – 16 % |
| Drawn tube, T6 (min) | 290 MPa / 42 ksi | 240 MPa / 35 ksi | 8 – 10 % |
| Extruded tube, T4 (min) | 180 MPa / 26 ksi | 110 MPa / 16 ksi | 16 % |
| Extruded tube, T6 / T6511 (min) | 260 MPa / 38 ksi | 240 MPa / 35 ksi | 8 – 10 % |
| 6061-T6, typical | 310 MPa / 45 ksi | 276 MPa / 40 ksi | 12 – 17 % |
Exact elongation limits depend on wall thickness and whether a full-section or strip specimen is tested. Your certificate states the actual results against the ordered specification.
Physical properties of 6061 (T6)
- Density
- 2.70 g/cm³ (0.0975 lb/in³)
- Modulus of elasticity
- 68.9 GPa (10,000 ksi)
- Thermal conductivity
- 167 W/m·K
- Electrical conductivity
- About 43 % IACS
- Coefficient of thermal expansion
- 23.6 µm/m·°C (20 – 100 °C)
- Melting range
- 582 – 652 °C
For hydraulic design, allowable working pressure depends on outside diameter, wall thickness, temperature and the safety factor in the system standard, not just tensile strength. Burst pressure is often estimated with Barlow's formula (P = 2·S·t / D), but the governing aircraft or system specification sets the factor between burst and working pressure.
Drawn, extruded, seamless and structural tube compared
Extruded seamless tube
Pushed through a die over a mandrel from a pierced or hollow billet, with no weld seam. Larger sizes and thicker walls than drawn tube; used for structural parts and machined sleeves.
Structural (porthole) tube
Extruded through a bridge or porthole die, so the metal flows round the mandrel and rejoins in solid-state weld lines. Fine for frames and railings, but not accepted where a specification requires seamless tube for pressure service.
Hydraulic tube
Seamless drawn tube in T4 or T6, with extra tests such as flaring, flattening and eddy-current or pressure testing, plus strict limits on surface and bore defects.
Pipe (Schedule 40 / 80)
Extruded or drawn 6061-T6 pipe to ASTM B241 or B429 in ASME pipe sizes. Common on ground equipment, test rigs and tooling.
Square, rectangular and oval tube
Extruded or drawn shapes in T6 for frames, seat structure, wing ribs in light aircraft and drone booms. Oval and streamline tube suits struts and fairings.
6061 aircraft tube sizes
Supply range
- Drawn seamless round tube
- OD about 3 – 100 mm (1/8 – 4 in); wall about 0.4 – 12.7 mm
- Small precision drawn tube
- OD from about 1 mm, wall from about 0.1 mm, for instrument and capillary tube
- Extruded round tube
- OD about 6 – 500 mm; wall about 1 – 50 mm
- Square and rectangular tube
- From 10 × 10 mm up to about 300 × 300 mm; wall 1 – 10 mm and above
- Pipe
- NPS 1/8 – 12 in, Schedule 10, 40 and 80
- Lengths
- Random or fixed lengths, commonly 3 – 6 m (12 – 20 ft); cut to length on request
Hydraulic tube is normally ordered in imperial sizes (for example 3/8 in × 0.035 in) to match AN, MS and AS fittings.
Common aircraft hydraulic and fluid-line sizes, with weight per metre of 6061 (density 2.70 g/cm³):
| OD (in) | Wall (in) | OD × wall (mm) | kg per metre | lb per foot |
|---|---|---|---|---|
| 1/4 | 0.035 | 6.35 × 0.89 | 0.041 | 0.028 |
| 5/16 | 0.035 | 7.94 × 0.89 | 0.053 | 0.036 |
| 3/8 | 0.035 | 9.52 × 0.89 | 0.065 | 0.044 |
| 3/8 | 0.049 | 9.52 × 1.24 | 0.087 | 0.059 |
| 1/2 | 0.035 | 12.70 × 0.89 | 0.089 | 0.060 |
| 1/2 | 0.049 | 12.70 × 1.24 | 0.121 | 0.081 |
| 5/8 | 0.035 | 15.88 × 0.89 | 0.113 | 0.076 |
| 5/8 | 0.049 | 15.88 × 1.24 | 0.154 | 0.104 |
| 3/4 | 0.049 | 19.05 × 1.24 | 0.188 | 0.126 |
| 3/4 | 0.065 | 19.05 × 1.65 | 0.244 | 0.164 |
| 1 | 0.049 | 25.40 × 1.24 | 0.255 | 0.171 |
| 1 | 0.065 | 25.40 × 1.65 | 0.333 | 0.223 |
| 1-1/4 | 0.065 | 31.75 × 1.65 | 0.422 | 0.283 |
| 1-1/2 | 0.065 | 38.10 × 1.65 | 0.510 | 0.343 |
| 2 | 0.083 | 50.80 × 2.11 | 0.871 | 0.585 |
6061-T6 pipe in standard ASME B36.10 dimensions:
| NPS | OD (in / mm) | Sch 40 wall (in) | Sch 40 kg/m | Sch 80 wall (in) | Sch 80 kg/m |
|---|---|---|---|---|---|
| 1/2 | 0.840 / 21.3 | 0.109 | 0.44 | 0.147 | 0.56 |
| 3/4 | 1.050 / 26.7 | 0.113 | 0.58 | 0.154 | 0.76 |
| 1 | 1.315 / 33.4 | 0.133 | 0.86 | 0.179 | 1.11 |
| 1-1/4 | 1.660 / 42.2 | 0.140 | 1.16 | 0.191 | 1.54 |
| 1-1/2 | 1.900 / 48.3 | 0.145 | 1.39 | 0.200 | 1.86 |
| 2 | 2.375 / 60.3 | 0.154 | 1.87 | 0.218 | 2.57 |
| 2-1/2 | 2.875 / 73.0 | 0.203 | 2.97 | 0.276 | 3.93 |
| 3 | 3.500 / 88.9 | 0.216 | 3.88 | 0.300 | 5.25 |
| 4 | 4.500 / 114.3 | 0.237 | 5.53 | 0.337 | 7.68 |
| 6 | 6.625 / 168.3 | 0.280 | 9.72 | 0.432 | 14.64 |
| 8 | 8.625 / 219.1 | 0.322 | 14.63 | 0.500 | 22.23 |
| 10 | 10.750 / 273.1 | 0.365 | 20.74 | 0.594 | 33.01 |
| 12 | 12.750 / 323.8 | 0.406 | 27.43 | 0.687 | 45.35 |
Wall thicknesses follow ASME B36.10; weights are calculated for 6061 at 2.70 g/cm³. Use the tube weight calculator for other sizes.
Tolerances, testing and certification
Drawn tube to AMS specifications is held to the close-tolerance tables for OD, wall and straightness in ANSI H35.2, with some specifications (such as AMS 4079) calling for tighter "close tolerance" limits. Extruded tube follows the extruded-product tables, which are wider.
Typical tests for aircraft tube
- Chemistry
- Analysis per cast
- Tensile
- Per lot, on full-section tube or strip specimens
- Flare and flattening
- Sample tubes flared on a cone and flattened between plates without cracking, to prove formability
- Non-destructive testing
- Eddy-current or ultrasonic inspection for seams, laps and bore defects where the specification requires
- Pressure test
- Hydrostatic or pneumatic proof testing on request or when specified
- Surface and bore
- Visual inspection; limits on scratches, die lines and pits that could start fatigue cracks
- Certificate
- EN 10204 3.1 certificate with specification, revision, lot and test results; third-party inspection on request
Lengths are capped or plugged at both ends and packed in rigid cases, so the bore stays clean. Hydraulic tube is often required to be supplied clean and dry inside, free from chips and drawing lubricant residue; state any cleanliness requirement on the order.
Bending, flaring, joining and finishing
Bending
Use mandrel benders for thin walls. T4 bends more tightly than T6; a centreline radius of about 3 × OD is a common starting point for T6 hydraulic tube, with tighter radii possible in T4 or O.
Flaring
37° flares for AN/MS fittings are routinely made in T4 and T6 drawn tube. Use correctly sized flaring tools and deburr the tube end to avoid split flares.
Swaging and beading
Beads for hose clamps and swaged permanent fittings are common in fuel and air lines; follow the fitting maker's tooling data.
Welding
TIG and MIG with 4043 or 5356 filler. Strength near the weld falls towards T4 levels unless the assembly is solution treated and aged again.
Heat treatment
O and T4 tube can be formed and then aged to T6. Aerospace heat treatment follows AMS 2770 with pyrometry to AMS 2750.
Finishing
Anodise (Type II or III) or apply conversion coating for corrosion protection and primer adhesion; colour anodising is used to identify systems.
Where 6061 tube is used in aircraft and spacecraft
| System or part | Typical tube form | Usual temper |
|---|---|---|
| Hydraulic pressure and return lines | Drawn seamless hydraulic tube (AMS 4083 / 4081) | T6 or T4 |
| Fuel, oil and coolant lines | Drawn seamless tube | T6 or O |
| Pneumatic, vent and drain lines | Drawn seamless tube | T6 or O |
| Electrical conduit | Drawn tube (AMS 4080 / 4082) | O or T6 |
| Control rods and push-pull tubes | Drawn or extruded round tube | T6 |
| Struts, frames and seat structure | Extruded round, square and rectangular tube | T6 |
| Ground-support equipment and stands | Extruded tube and Schedule 40/80 pipe | T6 |
| Satellite and launch-vehicle trusses and lines | Drawn or extruded tube | T6 |
| Drone booms and light-aircraft fuselage frames | Drawn or extruded round and square tube | T6 |
A typical light-aircraft or business-jet hydraulic installation illustrates the choices. Pressure lines in the wheel wells, where tubes are short and heavily bent, are made from T4 tube to AMS 4081 so that tight bends and 37° flares form without cracking. Long straight runs through the fuselage use T6 tube to AMS 4083 for the extra strength margin. Low-pressure return and case-drain lines may use thinner walls in the same alloy, and conduits for wiring use O or T6 general-purpose tube to AMS 4080 or AMS 4082. Every length is identified by specification and lot, so a replacement line made years later can be traced back to the same requirements.
The same tube is used widely outside aerospace: bicycle and motorcycle frames, sports equipment, truck and trailer frames, marine railings and towers, scaffolding and structural framing, and tubular bus conductors in substations.
6061 tube compared with 2024, 5052, 3003 and 6063
| Property | 6061-T6 | 2024-T3 | 5052-O / H32 | 3003-H14 | 6063-T6 |
|---|---|---|---|---|---|
| Typical tensile strength | 310 MPa | 485 MPa | 195 – 230 MPa | 150 MPa | 240 MPa |
| Formability (flaring, bending) | Good (better in T4) | Fair | Very good | Excellent | Good |
| Weldability | Good | Poor | Excellent | Excellent | Good |
| Corrosion resistance | Very good | Fair | Excellent | Excellent | Very good |
| Typical aircraft use | Hydraulic, fuel lines, structure | High-strength lines and struts | Fuel and oil lines | Low-pressure lines, ducts | Trim, non-structural frames |
Choose 2024-T3 where higher tube strength is needed and welding is not, 5052 for very formable fuel and oil lines, 3003 for low-pressure ducting, and 6063 for decorative or lightly loaded frames. 6061 covers the middle ground and is the most widely available aircraft tube alloy.
How to order 6061 aircraft tube
- SpecifyAlloy and temper, OD and wall (or NPS and schedule), length, any cleanliness or pressure-test requirement, quantity and the governing specification with its revision (for example AMS 4083, AMS 4081 or ASTM B210).
- ConfirmWe confirm the specification can be met, the tolerance class, any extra tests and the delivery terms (EXW, FOB, CIF or DAP).
- InspectMaterial is checked for dimensions, surface condition and identification; tests named on the order are carried out or arranged with a third party.
- DocumentEach lot ships with a mill test certificate to EN 10204 3.1 showing chemistry and mechanical results, traceable to the cast or lot number.
- Pack and shipExport packing in sealed, moisture-protected wooden cases or on pallets, shipped by sea or air to your port or door.
References and standards
- SAE AMS 4083 – Aluminum Alloy Tubing, Hydraulic, Seamless, Drawn, Round, 6061-T6
- SAE AMS 4080 – Aluminum Alloy, Drawn Seamless Tubing, 6061-O
- SAE AMS 4082 – Aluminum Alloy, Drawn Seamless Tubing, 6061-T6
- ASTM B210/B210M – Standard Specification for Aluminum and Aluminum-Alloy Drawn Seamless Tubes
- ASTM B241/B241M – Standard Specification for Aluminum and Aluminum-Alloy Seamless Pipe and Seamless Extruded Tube
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits (Teal Sheets)
6061 aircraft aluminium (aluminum) tube: frequently asked questions
Which specification covers 6061-T6 hydraulic tube?
AMS 4083 covers seamless drawn 6061-T6 hydraulic tube. AMS 4081 covers the same product in T4 for easier flaring and bending; older drawings may cite AMS-T-7081 (formerly MIL-T-7081).
What is the difference between AMS 4082 and AMS 4083?
Both are drawn seamless 6061-T6 tube. AMS 4083 is the hydraulic grade with extra formability and inspection requirements for pressure lines; AMS 4082 is general-purpose tube for brackets, conduits and low-pressure lines.
Can structural (porthole) extruded tube be used for aircraft hydraulic lines?
No. Porthole tube contains extrusion weld lines. Pressure and fluid lines need seamless drawn tube to an aerospace hydraulic specification.
Should I buy 6061 tube in T4 or T6?
T6 for straight runs and moderate bends where full strength is wanted. T4 where tight bends or heavy flaring are needed; T4 tube can be aged to T6 after forming if the strength is required.
How much does 6061 aluminium tube weigh?
Weight per metre = π × (OD − wall) × wall × 2.70 / 1000, with dimensions in mm. A 3/8 in × 0.035 in tube weighs about 0.065 kg/m; 2 in Schedule 40 pipe about 1.87 kg/m.
Is 6061 tube suitable for aircraft fuel lines?
Yes. Drawn seamless 6061 in O or T6 is widely used for fuel, oil and vent lines, as is 5052. The system specification sets the alloy, temper and pressure rating.
Can Metline supply 6061 aircraft tube cut to length with certificates?
Yes. Tube is supplied in random, fixed or cut lengths, capped and packed in rigid cases, with an EN 10204 3.1 certificate to the ordered specification, to customers worldwide.
Need 6061 tube for aircraft or ground equipment?
Send the size, temper, length, quantity and specification. Our team will reply with availability, test plan and a delivered price.
