3003 Cold Drawn Seamless Aluminium Tube
3003 seamless tube is extruded from a hollow billet with no longitudinal weld seam, then cold drawn (or cold rolled) to final size for close tolerances, thin walls and a smooth bore. Without seam welds it withstands internal pressure, expansion and flaring more reliably than welded or port-hole tube, which is why it is specified for condensers, evaporators, refrigerant lines and pressure tubing. Metline supplies 3003 seamless tube in O, H14 and H18, worldwide.
- Alloy
- 3003 (Al-Mn-Cu)
- Tempers
- O, H12, H14, H16, H18
- Route
- Seamless extrusion + cold drawing
- Standards
- ASTM B210 · B234 · EN 754
What makes 3003 seamless tube different?
"Seamless" describes how the hollow is formed. A solid or pierced billet is pushed over a mandrel so the tube wall is continuous all round, with no weld line where metal has rejoined. Drawing then reduces diameter and wall to precise final dimensions.
Aluminium tube can be made three ways: welded from strip, extruded through a port-hole (bridge) die, which leaves internal weld lines where the metal streams rejoin, or extruded seamlessly over a mandrel. Port-hole and welded tube are fine for frames and low-pressure uses. For tubes that are expanded into fins, flared, bent tightly or held under refrigerant pressure for decades, a seamless wall removes the most likely failure path.
Cold drawing adds a second advantage. Each pass through a die over a plug or mandrel improves roundness, concentricity and surface finish, so drawn seamless 3003 tube holds much tighter tolerances than as-extruded tube. The amount of cold work in the last pass, and whether a final anneal is applied, sets the temper from soft O to full-hard H18.
How cold drawn seamless 3003 tube is produced
- Cast and homogeniseDC-cast 3003 billet is homogenised to even out the manganese-bearing particles for consistent drawing.
- Seamless extrusionThe billet is pierced or bored and extruded over a mandrel into a thick-walled hollow (the "tube shell" or "mother tube").
- Cold drawing or rollingThe shell is drawn through dies over plugs or a floating mandrel, or cold rolled on a pilger mill, in several passes to reduce OD and wall.
- Intermediate annealBetween heavy passes the tube is annealed to restore ductility.
- Final temperThe last pass and any final anneal set the temper: O (fully annealed), H12 to H18 (increasing cold work).
- Finish and testStraightening, cutting, cleaning, eddy-current or leak testing, and inspection of dimensions and surface.
3003 chemical composition (wt %)
| Element | Minimum | Maximum | Role in the alloy |
|---|---|---|---|
| Silicon (Si) | — | 0.6 | Impurity |
| Iron (Fe) | — | 0.7 | Impurity |
| Copper (Cu) | 0.05 | 0.20 | Small addition; raises strength and shifts corrosion potential |
| Manganese (Mn) | 1.0 | 1.5 | Main alloying element: about 20 % more strength than 1100 |
| Zinc (Zn) | — | 0.10 | Impurity |
| Others, each / total | — | 0.05 / 0.15 | |
| Aluminium (Al) | Remainder | About 96.8 – 99 % |
Properties of 3003 seamless tube
Typical values below are Aluminum Association and ASM data. ASTM B210 and B234 set minimum tensile values by temper and wall: about 97 MPa (14 ksi) for O and 138 MPa (20 ksi) for H14.
| Temper | Condition | Tensile strength | Yield strength | Elongation | Hardness |
|---|---|---|---|---|---|
| O | Annealed | 110 MPa / 16 ksi | 42 MPa / 6 ksi | 30 – 40 % | 28 HB |
| H12 | Quarter hard | 131 MPa / 19 ksi | 124 MPa / 18 ksi | 10 – 20 % | 35 HB |
| H14 | Half hard | 152 MPa / 22 ksi | 145 MPa / 21 ksi | 8 – 16 % | 40 HB |
| H16 | Three-quarter hard | 179 MPa / 26 ksi | 172 MPa / 25 ksi | 5 – 14 % | 47 HB |
| H18 | Full hard | 200 MPa / 29 ksi | 186 MPa / 27 ksi | 4 – 10 % | 55 HB |
| H112 | As extruded | Close to O; minimums per ASTM B221 | — | — | — |
Physical properties of 3003 (typical)
- Density
- 2.73 g/cm³
- Modulus of elasticity
- 68.9 GPa
- Thermal conductivity
- About 193 W/m·K (O); 159 W/m·K (H14)
- Electrical conductivity
- About 50 % IACS (O); 41 % IACS (H14)
- Thermal expansion (20 – 100 °C)
- 23.2 µm/m·°C
- Melting range
- 643 – 654 °C
Estimating burst pressure of 3003 seamless tube
Barlow's formula, P = 2 S t / D, gives a quick theoretical burst pressure from tensile strength S, wall t and outside diameter D. The table uses typical tensile strengths of 110 MPa (O) and 152 MPa (H14). These are failure estimates only: working pressure must be set with the safety factor or allowable stress in your design code (for example ASME B31.3, or refrigeration standards such as ISO 5149 / EN 378), and brazed tube should be rated at annealed (O) strength.
| OD × wall (mm) | Theoretical burst, O (bar) | Theoretical burst, H14 (bar) |
|---|---|---|
| 6.35 × 0.71 | 246 | 340 |
| 9.52 × 0.81 | 187 | 259 |
| 12.7 × 0.89 | 154 | 213 |
| 15.88 × 1 | 139 | 191 |
| 19.05 × 1.24 | 143 | 198 |
| 25.4 × 1.65 | 143 | 197 |
Barlow's formula ignores tolerances, ovality, corrosion allowance and temperature. Treat the figures as a comparison tool, not a rated pressure.
Tolerances, testing and inspection
Quality requirements
- Dimensional tolerances
- ASTM B210 / B234 (ANSI H35.2) for drawn tube; EN 754-7 for EN orders. Drawn tube tolerances on OD and wall are significantly tighter than extruded tube.
- Leak test
- Pneumatic or hydrostatic test, or eddy-current testing, as specified (required for heat-exchanger tube under B234)
- Expansion / flare test
- Samples are expanded or flared to show the tube will accept fitting and fin expansion without cracking
- Tensile test
- Per lot, reporting tensile and yield strength and elongation
- Cleanliness
- Degreased bore and capped ends for refrigeration service on request
- Certification
- EN 10204 3.1 mill test certificate
Typical sizes and weight per metre
| OD (mm) | Wall (mm) | ID (mm) | Mass (kg/m) |
|---|---|---|---|
| 6.35 | 0.71 | 4.93 | 0.034 |
| 7 | 0.6 | 5.8 | 0.033 |
| 8 | 0.8 | 6.4 | 0.049 |
| 9.52 | 0.81 | 7.9 | 0.061 |
| 10 | 1 | 8 | 0.077 |
| 12 | 1 | 10 | 0.094 |
| 12.7 | 0.89 | 10.92 | 0.090 |
| 15.88 | 1 | 13.88 | 0.128 |
| 16 | 1.2 | 13.6 | 0.152 |
| 19.05 | 1.24 | 16.57 | 0.189 |
| 20 | 1.5 | 17 | 0.238 |
| 22 | 1.5 | 19 | 0.264 |
| 25.4 | 1.65 | 22.1 | 0.336 |
| 30 | 2 | 26 | 0.480 |
| 38.1 | 2 | 34.1 | 0.619 |
| 50 | 3 | 44 | 1.209 |
Drawn seamless tube is normally ordered from small capillary sizes up to medium diameters; larger sizes are supplied as extruded seamless tube. Lengths can be straight, cut to size or coiled in the O temper.
Where seamless 3003 tube is specified
- Condensers and evaporators in air-conditioning, heat pumps and commercial refrigeration
- Refrigerant lines and capillary tube where leak-tightness over the product life is critical
- Oil coolers and hydraulic coolers with expanded tube-and-fin construction
- Instrument and gas lines needing clean bores and reliable flare joints
- Precision mechanical parts such as sleeves, rollers and antenna elements made from tight-tolerance tube
Seamless vs port-hole vs welded 3003 tube
| Factor | Seamless drawn | Port-hole extruded | HF welded |
|---|---|---|---|
| Weld lines | None | Internal extrusion welds | One longitudinal seam |
| Pressure and expansion reliability | Highest | Lower; seams can split | Good when seam is controlled |
| Tolerances | Tightest | Moderate | Good |
| Wall thickness | Thin to medium | Medium to heavy | Very thin possible |
| Cost | Higher | Lower | Lowest at high volume |
| Typical use | Refrigeration, pressure lines | Frames, non-pressure tube | Radiators, condensers |
Our guide to seamless aluminium tube covers the trade-offs in more depth.
How to order
- SpecifyOD, wall, temper, length or coil, governing standard (ASTM B210, B234 or EN 754) and test needs.
- QuoteWe confirm tolerances, testing, certification and delivery terms (EXW, FOB, CIF or DAP).
- ShipCapped, cleaned tube in crates or coils with an EN 10204 3.1 certificate.
References and standards
- ASTM B234/B234M – Drawn Seamless Aluminium-Alloy Tubes for Condensers and Heat Exchangers
- ASTM B210/B210M – Drawn Seamless Tubes
- EN 754-2 and EN 754-7 – Cold drawn rod, bar and tube: mechanical properties; seamless tube tolerances
- ANSI H35.2 – Dimensional Tolerances for Aluminum Mill Products (The Aluminum Association)
3003 seamless aluminium (aluminum) tube: frequently asked questions
What is the difference between seamless and welded aluminium tube?
Seamless tube is extruded over a mandrel so the wall is continuous, then drawn to size. Welded tube is roll-formed from strip and joined along one seam. Seamless tube is preferred for pressure, expansion and flaring; welded tube is economical for high-volume radiator and condenser tube.
Why is port-hole extruded tube not called seamless?
A port-hole die splits the metal into streams that rejoin around a mandrel bridge, leaving longitudinal extrusion welds. These are sound for most uses but are weaker under pressure and expansion than a truly seamless wall.
What temper is best for refrigeration tube?
O (annealed) is common because it bends, flares and expands easily. Brazing will anneal the tube anyway, so design pressure should be based on O-temper strength.
What does "cold drawn (rolled)" mean?
After extrusion the tube shell is reduced cold, either by drawing through dies over a mandrel or by cold rolling on a pilger mill. Both improve tolerances and surface and add strength through cold work.
Which standard covers 3003 heat-exchanger tube?
ASTM B234 covers drawn seamless tube for condensers and heat exchangers, including 3003; ASTM B210 covers general-purpose drawn seamless tube; EN 754 covers cold drawn tube in Europe.
Need precision 3003 seamless tube?
Send size, temper, test requirements, quantity and destination. We will confirm tolerances and a delivered price.
