Introduction
This article explains the chemical composition of C12000 copper. C12000 is the DLP grade of phosphorus-deoxidized copper, where DLP stands for deoxidized low residual phosphorus. It is the standard material for copper water tube, ACR tube and heat exchanger tubing because the phosphorus removes oxygen from the melt and makes the metal safe to braze, weld and bright-anneal.
Composition and Grade Identity
C12000 contains at least 99.90 percent copper with a phosphorus residual of 0.004 to 0.012 percent. It is important to distinguish DLP from DHP: the DHP grade C12200 carries a higher phosphorus range of 0.015 to 0.040 percent and a slightly lower conductivity of about 85 percent IACS, while C12000 DLP retains roughly 90 to 95 percent IACS. The Chinese equivalent of the low-phosphorus product is TP1, and the higher-phosphorus product is TP2, with both defined in GB/T 5231.
Why Phosphorus Is Added
Phosphorus acts as a deoxidizer during melting. It combines with the oxygen in the melt so that the cast metal contains no cuprous oxide. Without oxide particles at the grain boundaries, the copper cannot suffer hydrogen embrittlement during brazing or welding, which is why deoxidized grades are mandatory for joined tube systems in plumbing, air conditioning and heat exchange.
| Property | C12000 DLP | C12200 DHP |
|---|---|---|
| Phosphorus | 0.004 - 0.012% | 0.015 - 0.040% |
| Conductivity | 90 - 95% IACS | About 85% IACS |
| Copper min | 99.90% | 99.90% |
| Chinese grade | TP1 | TP2 |
Properties and Working Behavior
DLP copper tube offers good thermal conductivity, high ductility, and excellent bending, flaring and expanding behavior, which allows reliable swaged and brazed joints. It is produced in drawn tempers with strength depending on the degree of cold work, and it responds predictably to annealing. The material also has good corrosion resistance in fresh water, seawater and many chemical media.
Applications
Typical uses are plumbing water tube, boiler and condenser tubing, ACR tube for refrigeration and air conditioning, oil coolers, heat exchanger tubes and general engineering tube. The grade is available as straight tube and coil, and it is covered by ASTM B75, B88, B280 and B68 according to the product form.
Verification and Buying
Confirm the phosphorus range, conductivity, temper and dimensions on the order, and verify the mill certificate against the relevant standard. For pressure applications, check the hydrostatic test requirement and the tube tolerances before acceptance.
