How Heat-Treated Brass Achieves Dezincification Resistance

How Heat-Treated Brass Achieves Dezincification Resistance

Plumbing and HVAC systems expose brass fittings to municipal water, glycol loops, and years of temperature swings. That exposure creates a real risk: dezincification, a corrosion process that strips zinc from brass and leaves a weak, porous structure behind. Resistance to dezincification comes down to alloy chemistry and heat treatment, confirmed through standardized lab testing. Learn more about the metallurgy behind dezincification, the heat treatment that produces dezincification-resistant brass, and the test that confirms it.

What Is Dezincification, and Why Does It Matter in Plumbing Systems?

Dezincification happens when zinc leaches out of a copper-zinc alloy, leaving behind a soft, copper-rich layer that cracks under pressure. The reaction speeds up under these water conditions:

• High chloride content
• Low pH
• Elevated temperature
• Stagnant or low-flow sections of a line

These conditions turn up in municipal supply lines and closed HVAC loops alike. A dezincified valve body can look intact from the outside while its wall thickness drops well below the rated strength. For a design engineer specifying components behind a wall or under a slab, that hidden failure mode can be especially harmful. Choosing dezincification-resistant brass helps prevent the kind of hidden failure that surface inspection alone can’t catch.

The Metallurgy: Alpha vs. Beta Phase in Copper-Zinc Alloys

Standard brass forms two crystal structures within the same alloy: alpha phase and beta phase. Alpha phase carries less zinc and resists corrosion. Beta phase carries more zinc, machines faster, and corrodes faster too. A valve body cut from standard brass often contains scattered beta grains, and each one gives dezincification a foothold.

Dezincification-resistant brass begins with a formulation designed to keep beta-phase content low from the outset. From there, the alloy still needs one more step to reach full resistance to dezincification: heat treatment.

How Heat Treatment Creates a Dezincification-Resistant Structure

Heat treatment converts the alloy’s remaining beta phase into a stable alpha phase. Manufacturers heat the cast or forged brass to a controlled temperature, hold it there for a set period, then cool it under controlled conditions. This step redistributes zinc atoms into one uniform alpha structure instead of the patchy alpha-beta mix found in untreated brass. Alpha grains resist selective zinc leaching, so the finished part carries real resistance to dezincification. Without this step, the valve retains small beta pockets that can corrode from the inside out over time.

Verifying Performance with the ISO 6509 Test

ISO 6509 gives engineers a repeatable way to confirm resistance to dezincification instead of relying solely on a supplier’s word. In a lab, a cross-section of the brass is exposed to a corrosive test solution for a set exposure period, and then the depth of the corroded layer is measured under a microscope against the maximum attack depth the standard allows.

All RWV dezincification-resistant brass valves are tested against this standard by an independent laboratory, so the alloy and the heat treatment are verified to hold up under conditions built to mimic years of field exposure.

Specifying DZR Brass Valves from RED-WHITE VALVE CORP.

At RED-WHITE VALVE CORP. (RWV), we manufacture every brass and bronze valve in our own factories, which keeps alloy sourcing, heat treatment, and quality checks under one roof instead of scattered across supply chain partners. For plumbing and HVAC specifications where potable water or glycol contact is a factor, RWV supplies dezincification-resistant brass valves and ISO 6509 test data to document that resistance—closing off a failure mode that might otherwise surface years after installation.

Learn more about the advantages of DZR brass valves to see how these valves benefit specific plumbing and HVAC applications.

Contact RWV to Learn More About DZR Brass Valves

Resistance to dezincification comes from two steps working together: formulating an alloy with low beta phase content and a heat treatment cycle that locks in a uniform alpha structure, confirmed by ISO 6509 testing. If you’re specifying brass valves for a plumbing or HVAC project and want to talk through alloy grade, heat treatment records, or test data, contact RWV or request a quote to start a conversation.

PICVs Explained: How Pressure Independent Control Valves Work

In commercial HVAC hydronic systems, maintaining precise flow control is harder than it sounds. Pressure fluctuations ripple through the distribution loop every time a zone valve opens or closes, and traditional control mechanisms often can’t keep up. That’s where the pressure-independent control valve, or PICV, comes in.

A PICV handles flow regulation and differential pressure compensation in a single valve body. For design engineers and mechanical contractors working on variable-flow systems, understanding how these valves work is essential before specifying or installing them.

What Is a Pressure-Independent Control Valve (PICV)?

A pressure-independent control valve (PICV) maintains a maximum flow rate even as system pressure changes. Once the flow rate is set, the valve keeps it constant regardless of pressure variations.

PICVs are commonly specified under several names, such as PICV valve or PIC valve, but they all describe the same all-in-one device. Design engineers value them because they remove the need for manual balancing at each terminal unit.

How a PICV Combines Flow Control and Balancing in One Body

Most PICVs integrate three functional elements:

• A differential pressure regulator that compensates for pressure fluctuations across the valve
• A flow-limiting cartridge that caps the maximum flow to a preset value
• A modulating control actuator that adjusts flow in response to a control signal

The differential pressure regulator maintains a constant flow as system pressure changes, while the actuator modulates to meet the load. As a result, the valve provides the flow rate the building automation system (BAS) commands rather than the flow the network pressure would otherwise force through.

PICVs vs. Traditional Two-Way Control Valves

A standard two-way control valve responds only to a control signal. It has no mechanism to compensate for pressure changes. As system pressure shifts, actual flow through the valve drifts away from design intent.

To correct for this in traditional systems, engineers often add separate manual balancing valves to each circuit and commission the system after installation. This process can be time-consuming, and the balance can drift over time as zones are added or modified.

PICVs eliminate that separate balancing step. Key differences at a glance:

Fewer devices per circuit reduce the number of connections, lower installation labor requirements, and simplify the commissioning process for mechanical contractors.

Where PICVs Fit in Commercial HVAC Water Systems

PICVs are designed for variable-flow hydronic systems—buildings served by variable-speed pumping where flow through each zone is constantly changing. They’re commonly found in:

• Fan coil units (FCUs) in hotels, office buildings, and healthcare facilities
• Air handling units (AHUs) on chilled water and hot water circuits
• Active chilled beams
• Radiant heating and cooling panels

In constant-flow primary loops, PICVs are typically used as flow limiters rather than as the primary balancing mechanism, since traditional balancing valves already handle steady-state flow control there. In general, specify PICVs if the system operates under variable differential pressure.

Selecting and Specifying PICVs

When specifying a PICV valve, engineers and contractors typically define:

• Design flow rate: The maximum flow rate that the valve will pass at full open.
• Pressure differential range: RWV’s 9707 series PICVs operate within roughly 3–60 psi, with the exact minimum varying by valve size and flow preset.
• Control signal type: 0–10V modulating or ON/OFF.
• Connection size and end connections: To match the piping configuration.
• Actuator specifications: Fail position, manual override, and feedback requirements.

One common specification mistake is selecting a PICV based on pipe size rather than design flow. Oversizing a PICV valve can reduce control resolution and cause hunting.

For projects requiring balancing valves or other hydronic components, review the full valve specifications early in design to avoid conflicts with the PICV’s built-in balancing.

PICVs From RED-WHITE VALVE CORP.

PICVs are one part of a broader hydronic valve strategy, and picking the right combination of control, isolation, and balancing valves means matching each device to the system’s flow and pressure conditions.

RED-WHITE VALVE CORP. has supplied high-quality valves to the plumbing, commercial, and HVAC markets for over 50 years, including a line of DZR brass PICVs for hydronic control applications:

• 9707R DZR Brass PICV. The base model, with an NPSM end for tailpieces.
• 9707T DZR Brass PICV with Tailpieces. Adds FNPT, MNPT, and solder tailpieces for simpler installation.
• 9707IBV DZR Brass PICV with Isolation Ball Valve. Adds an integrated isolation ball valve with FNPT, MNPT, solder, or PEX (F1960) tailpieces, combining isolation and flow control in one body.

All three models offer full-stroke modulation, head-loss measurement test points, and ready-to-mount ON/OFF or modulating actuators, with a flow range of 0.12–15.9 GPM.

If you’re working through a valve selection question or need support on a commercial hydronic project, contact our team or request a quote to get started.