Dezincification-resistant (DZR) brass is brass made to resist a type of corrosion in which water leaches zinc out of the metal. It is used for plumbing and heating fittings in areas with aggressive water.
Ordinary brass can suffer dezincification when exposed to some waters. The zinc dissolves, leaving a weak, porous copper layer. Fittings can then weep, crack or fail under pressure.
How DZR brass works
Standard brasses with around 40% zinc contain two phases, called alpha and beta. The beta phase is most prone to dezincification. DZR brass uses a composition and heat treatment that limit the beta phase, and a small addition of arsenic protects the alpha phase.
The common European grade is CW602N, chemically CuZn36Pb2As. The older British name is CZ132. Some lead-free and low-lead brasses are also resistant to dezincification.
The composition alone is not enough. Many DZR parts need a controlled heat treatment after hot forging to reach the right structure. If the supplier skips it, the parts will look the same but may fail the test.
When it is required
Some markets and water authorities require DZR brass for fittings in drinking water systems, or for buried and concealed fittings. Requirements differ by country and by product standard. Your plumbing certifier or water authority can confirm what applies to your product.
DZR does not replace lead limits. A DZR brass with 2% lead may still fail drinking water rules. Read what lead-free brass is to check both requirements.
DZR brass also costs more to make. The alloy is harder to source in consistent quality, the heat treatment adds a step, and machining can be a little slower. Specify it where the market or the water needs it, and use standard brass elsewhere, such as on non-wetted parts of the same assembly.
How to test for it
- ISO 6509-1 sets the laboratory test method. Samples are held in a copper chloride solution, then cut and examined for the depth of dezincification.
- ISO 6509-2 gives assessment criteria, though many national standards set their own acceptance limits.
- The test should be run on parts from your production lot after all heat treatment, not on rod or a separate sample.
- The mill certificate should show arsenic within the grade limits, and the heat treatment record should match the lot.
Marking and traceability
Some markets expect DZR fittings to be marked, often with "DZR" or a recognised symbol. Ask your certifier what marking applies. Keep DZR and standard brass apart in the factory, because the parts look identical.
See brass alloys explained for how DZR grades sit beside the free-machining brasses.
Next step
We check documents, supervise production and have lots tested to the dezincification standard you name. To plan a DZR programme, book a free sourcing review.