What is a sacrificial anode rod?

A sacrificial anode rod is a metal rod, typically magnesium, that corrodes in place of the steel tank or structure it protects. Because magnesium is more electrochemically active than steel, it gives up its electrons first, drawing corrosion to itself and sparing the tank. This is the "sacrifice" — the rod is consumed so the protected metal isn't.

How does cathodic protection work?

Cathodic protection prevents corrosion by making the metal you want to protect the cathode of an electrochemical cell. A more active metal, in this case the sacrificial anode, becomes the anode and corrodes instead. In a water heater or storage tank, the magnesium rod supplies a small protective current throughout the water that stops the steel from rusting.

What is an anode rod made of?

Vanode's extruded anode rods are made of a magnesium alloy (typically AZ31D, though other alloys are also used) around a steel core wire that carries the electrical connection and provides structural support.

What size anode rod do I need?

Vanode manufactures rods in 12 diameters from 0.500 to 2.562 inches. The right size depends on the tank or vessel, the fitting it threads into, and the level of protection required. Just measure the size of the fitting (across the top) and the length of the entire anode, from the top of the fitting to the end of the rod.

How do I know which hex head fitting matches my rod?

Each hex head is sized to a specific rod diameter and NPT thread. For example, a 1-1/16" hex head with 3/4" NPT threads is used with both 0.750" and 0.840" rods. The full pairing chart is on our Heads & Fittings page.

What's the difference between rigid and flexible anode rods?

Rigid rods are straight and used where there's clearance to insert a full-length rod. Flexible rods are segmented or bendable (like sausage links), for tanks where overhead space is limited and a straight rod won't fit.

When should an anode rod be replaced?

An anode rod should be replaced once it's substantially consumed, before it can no longer protect the tank. Depending on the application, and water conditions, anodes should be checked about every 6 months and replaced whenever they are more than 50% consumed, in order to prevent whatever you're protecting from corroding.

Why choose magnesium over aluminum or zinc anodes?

Magnesium is the most electrochemically active of the common anode metals, giving it the strongest protective current. Magnesium is therefore well suited for most potable and freshwater applications. Aluminum anodes are typically used for salt or brackish water, and zinc anodes are the typical choice for saltwater.

What applications are Vanode anode rods used in?

Vanode rods are used in water heaters, storage tanks, boilers, and a range of industrial corrosion-protection applications including data centers (hyperscale and colocation data centers), water infrastructure (wastewater treatment, public water and power utilities), building/mechanical (boiler repair & maintenance, HVAC systems, chiller repair), facilities management (hospitals, hotels), engineering & service contractors (corrosion engineering, design & installation services, emergency vehicle services & repair), energy, marine, and equipment supply (oil & gas, plumbing equipment supply, solar equipment supply).

Can Vanode produce custom sizes or specifications?

Yes, our machine shop in Idaho can make a wide variety of custom sizes and specs, from 1/2" diameter rod & 1/2" in length, to 2.562" in diameter and 20 ft in length, and anything in between. We can machine various alloys and fittings as well depending on the specific application.

What core wire options are available?

Vanode rods use a steel core wire, 0.135" diameter on rods up to 1.315" and 0.188" on larger diameters.

Where are Vanode anode rods made?

Vanode has manufactured magnesium anodes in the USA since 1953, at our facility in Emmett, Idaho.