Sunday, January 20, 2013

Color Coding of Tungsten Electrodes

Paul,

IS THERE ANYONE ON YOUR STAFF THAT CAN TELL ME HOW TO IDENTIFY TUNGSTEN AFTER THE PAINT IS WORN OFF?

Signed Reader


There are 2 common weld processes that use a non-consumable, tungsten electrode, Gas Tungsten Arc Welding (GTAW/Tig/HeliArc) and Plasma Arc Welding (PAW). These electrodes come in a variety of compositions or alloys. Each composition serves a specific purpose.

Pure tungsten electrodes (AWS classification EWP) contain 99.50% tungsten. These electrodes provide good arc stability for AC welding on aluminum and magnesium. Their color designation is GREEN.

2% thoriated tungsten electrodes (AWS classification EWTh-2) contain 1.70 to 2.20% thorium. They are the most commonly used. Unlike pure tungsten, these electrodes are exceptional for DC electrode negative or straight polarity on carbon and stainless steels. Their color designation is RED.

2% ceriated tungsten electrodes (AWS classification EWCe-2) contain 1.80 to 2.20% cerium. These electrodes perform best in DC welding at low current settings but can be used in AC or DC processes. Their color designation is ORANGE.

1.5% lanthanated tungsten electrodes (AWS classification EWLa-1.5) contain 1.30 to 1.70% lanthanum, or lanthana. These electrodes have many of the same advantages as ceriated electrodes. They also closely resemble the conductivity characteristics of 2% thoriated tungsten. Their color designation is GOLD

Zirconiated tungsten electrodes (AWS classification EWZr-1) contain 0.15 to 0.40% zirconium. It is ideal for AC welding and under no circumstance is zirconiated recommended for DC welding. Their color designation is BROWN.

Each of these electrodes placed side-by-side look identical. For that reason a color code system has been developed to designate each. Short of sending them to a lab for analysis ($$$) once the color designation is gone, there is no way to tell what type of tungsten you're holding.

As the hack Tig (GTAW) welder I am, I keep short, unmarked tungstens in old military stick match containers. Each container is clearly marked as to the type of tungsten inside. Along with that, I always-always-always break down my torch when I'm done and store the tungsten in its designated container.

This works for me in my garage. This would not be a good practice in a manufacturing or code environment.

Once the marking is removed the tungsten is not traceable and you just lost control of your weld process.

PWC