You reach for a box of electrodes, put on your welding helmet, and then hold one of the steel pipes you’re going to weld up in front of you. The air smells like ozone and burnt flux. You grab a stick and touch it to another piece of metal to strike an arc. Only to find that you don’t even remember whether this was the correct rod for what you are doing.
Until you melt the metal or leave a hole-filled mess of a bead, welding seems like magic. Then comes the chart. That’s where it pays off. It turns what used to be a crapshoot into a quick reference table. The graph shows how dozen or so most common rods is broken out by type (coating), polarity, and application. No more blind guesses.
How to Pick the Right Welding Rod
To give you a little more confidence, let’s decode the number on the rods. All SMAW electrodes has a four digit number that will tell you precisely what they can and cannot do. The first two digits indicate the tensile strength in thousands of PSI. So if it’s a 70 series rod, then it’s tougher then say a 60 series rod. The third digit lets you know which positions you can weld in. A one indicates all positions. That’s what you need for an overhead or vertical application. The last digit tell you the polarity needed and type of coating.
Why does this matter? The coating determines how well the arc perform and sheds the slag from your joint. If you’re not paying attention to the coating, you are basically throwing some metal at something and praying it sticks. Low-hydrogen rods, such as the E7018, are the workhorse of structural welding. These has very specific storage requirements. To maintain their effectiveness, they need to be stored at a consistent temperature. At 250 degrees Fahrenheit or more. As the chart shows, moisture will destroy these electrodes. When the flux becomes moist, hydrogen cracks will appear in the weld. This is a catastrophic failure mode. It doesn’t become apparent until the joint fails under stress. So that’s the deal with those guys. They need to be kept hot, dry, and sealed till you’re ready to use them.
Cellulose rods like the E6010, however, don’t care about humidity nearly as much. They dig down deep and is ideal for pipe root passes. You can’t control them as well, though. That’s the trade-off.
Another place people get hung up on is amp settings. The infographic includes a scale showing rod diameter versus amps. Generally speaking a 1/8 inch rod will pull anywhere from 90, 140 amps. If you’re new to this, start on the low side. It’s better to add heat than repair a hole in your plate.
The diagram shows how different rods react to the same amperage. An iron powder rod such as an E7014 or an E7024, deposits metal quicker but generally needs a little more current. They were designed for fast paced production work in the flat position where they can lay down metal quick rather than worry about accuracy. In the vertical position they make a sloppy saggy mess.
And then there’s stainless. This adds a whole new level to it. There are different grades of stainless. On the chart they have E308L and E316L. The L means low carbon. Low carbon helps prevent sensitizing when you weld it. Use 308 if you’re matching 304 stainless and 316 if you need extra corrosion resistance for chemical applications or around salt water/marine. Don’t mix your carbon steel rods with your stainless rods. They’ll cross-contaminate each other and ruin the corrosion resistance. This little mistake will cost thousands in repairs down the road.
The other thing is how you do it. It’s not just about what type of rod you use. The arc should match the rod diameter. Too big an arc and you’re getting porosity and spatter. And pull the rod at a five to fifteen degree angle. Chip out the slag on each pass. Don’t skip the slag removal because then you trap inclusions which weaken the joint. All those sound simple, but they are the difference between a pretty bead and a strong one.
The visual guide is a quick refresher on the specs, but you have to learn the feel with your hands. There’s some science to welding. There’s also some muscle memory. The science, the chart, provides the physics. It shows material limits and the amps required. You supply the muscle memory.
Clean metal is key. Get rid of the mill scale and rust. Most porosity problems comes from dirt when welding in the shop. Protect your peepers with a good pair of lenses (shade 10 or 12). Start the arc fast with a match-like strike on quick start rods, and tap lightly on low-hydrogen sticks. Set the travel speed to roughly double the diameter of the rod; around twice as wide as the rod diameter. Go too slow and you stack metal. Go too fast and undercut the edge.
Remember, mastering the stick requires respecting the equipment and the material; so don’t try to force an arc. Relax and let the coating protect you. Set up by trusting the chart’s numbers and once you’re going, trust your own eyes and ears to tweak it as needed. A clean weld sounds like continuous bacon frying in the pan. Pops and sputters mean something ain’t right. Was the polarity set correctly? Is your clamp connected? Is the base metal dirty?
All of this takes time but before long the chart gets into your blood stream. You won’t have to look at the chart anymore to get the rod you need. You’ll naturaly sense when the arc wants to pull and automatically slow down. Metal will melt and join cleanly. Slag will come off effortlessly. Beads will be uniform and sit smoothly on the weld. Then you will know you’ve got it. Know what it is you hold.
