How Copper Tube Grades Are Named
Chinese designations follow GB/T 5231 for wrought copper and copper alloy grades, while the Japanese series under JIS H3100 and JIS H3300 is widely quoted in Asia and appears in older purchase documents. Both systems describe the same material families: pure copper with a guaranteed minimum copper content, oxygen-free copper with a controlled low oxygen level, and phosphorus-deoxidised copper in which a deliberate phosphorus addition removes the oxygen chemically.
Understanding which family a tube belongs to matters because the three families behave differently during brazing, forming and service. Pure copper voids the hydrogen embrittlement problem only if it is oxygen-free; deoxidised copper solves it by chemistry, at a small cost in electrical conductivity.
Composition and Characteristics of Each Grade
| Grade | Japanese equivalent | Key composition | Characteristic properties | Typical use |
|---|---|---|---|---|
| T2 | C1100 | Cu + Ag ≥ 99.90 % | High electrical and thermal conductivity, good ductility, corrosion resistance and weather resistance | Water supply and heating pipework, refrigeration piping, mechanical equipment, general fittings |
| TU2 | C1011 | Cu + Ag ≥ 99.95 %, O ≤ 0.003 %, total impurities ≤ 0.05 % | No hydrogen embrittlement, very high conductivity, good welding and low-temperature performance | Power supply and communication equipment, electronic products, vacuum and instrument tubing |
| TP1 | C1201 | Cu ≥ 99.90 %, P 0.004–0.012 % | Deoxidised, ductile, good extrusion and fusion welding behaviour, corrosion and weather resistant | Heat exchanger and condenser tube, air conditioning and refrigeration circuits |
| TP2 | C1220 | Cu ≥ 99.90 %, P 0.015–0.040 % | Deoxidised, excellent brazing and welding behaviour, good thermal and electrical conductivity | Air conditioning and refrigerator tube, heat exchanger tube, refrigeration and heating industries |
In the UNS system these grades correspond broadly to C11000 for T2, to the oxygen-free family including C10200 and C10100 for TU2, and to C12000 and C12200 for TP1 and TP2. A purchase order should quote one system and one grade, and should also state the temper, because the same grade is supplied annealed, half-hard and hard.
Delivered Condition, Thickness and Diameter Range
| Parameter | Range supplied | Note |
|---|---|---|
| Temper | M soft annealed, Y2 half-hard, Y hard, T extra hard | Higher temper means higher strength and lower elongation; the annealed state is used where field bending is required |
| Wall thickness | 0.5–40 mm | Tolerance approximately ±0.005 to ±0.02 mm depending on wall |
| Outside diameter | 3–219 mm | Tolerance generally within ±0.05 mm on the drawn product |
| Form | Straight lengths and coiled tube | Annealed tube is supplied in coils for HVAC and refrigeration installation |
Tolerances quoted above are order ranges rather than a single universal figure. The controlling document is the product standard named on the purchase order, for example GB/T 1527 for drawn copper and copper alloy tube, GB/T 18033 for seamless copper tube for water and gas, or EN 1057 for European water and gas duty.
Choosing Between the Four Grades
Choose T2 where cost and conductivity matter and the tube will not be exposed to reducing atmospheres during brazing.
Choose TU2 where the tube will be welded or brazed extensively, or where the bore must remain free of any internal oxide, as in electronic and vacuum equipment.
Choose TP1 for mildly aggressive cooling water and for fusion welded heat exchanger headers where a moderate phosphorus level is preferred.
Choose TP2 as the general-purpose deoxidised grade for air conditioning, refrigeration and heat exchange, because it is the most widely produced and most readily available of the four.
Processing and Handling Notes
All four grades cut, flare and bend in the same way when they are supplied in the annealed temper. The differences appear during thermal processing. Pure copper containing oxygen must not be brazed or annealed in hydrogen or in a strongly reducing atmosphere, because the internal oxide decomposes and steam is generated inside the wall. Deoxidised grades TP1 and TP2 and the oxygen-free grade TU2 are immune to this effect and are therefore preferred whenever furnace brazing, hydrogen annealing or closed-atmosphere welding is used.
Store tube under cover and cap the ends. The dark film that sometimes appears inside a coil is drawing lubricant residue rather than an indication of poor material, but for refrigeration duty the bore should still be clean and dry, and the tube should be nitrogen-purged during brazing to keep it that way.
FAQ
Q: What is the difference between T2 and TP2 copper tube?
T2 is pure copper with at least 99.90 % copper and no deliberate deoxidation, so it may contain oxygen. TP2 is phosphorus-deoxidised copper with 0.015 to 0.040 % phosphorus, which makes it safe for brazing and welding at a slight cost in conductivity.
Q: When should TU2 be selected instead of TP2?
Use TU2 where the highest purity is needed, for example electronic, communication, vacuum or low-temperature equipment, or where a completely oxide-free bore is essential.
Q: What does the phosphorus addition do in TP1 and TP2?
Phosphorus combines with the residual oxygen in the melt, so no cuprous oxide remains in the cast structure. Without that oxide the tube cannot suffer hydrogen embrittlement during brazing or reducing-atmosphere annealing.
Q: Which temper should be ordered for field bending?
Order the M soft annealed temper. Half-hard Y2 and hard Y tempers give higher strength but will crack if bent cold to a small radius without local annealing.
Q: What thickness and diameter range is normally available?
Wall thickness from 0.5 mm to 40 mm and outside diameter from 3 mm to 219 mm, with the exact tolerances set by the product standard quoted on the order.
Q: Can the four grades be identified visually?
Not reliably. All of them are reddish in colour. Grade confirmation requires chemical analysis of the heat and a material test certificate rather than a visual check.
