Preheating filler metal is a waste of time on most jobs

I keep seeing guys at the yard heating up their filler rods before they even strike an arc. Unless you're working in subzero temps or with some specialty alloy, that extra step does nothing for the weld. I've been doing this for 12 years in Seattle and never preheat rod, my X-rays come back clean every time. Anyone got a real reason they do this besides what some old timer told them?

2 comments

2 Comments

the_xena10d ago

Preheating filler rod is one of those things that sounds scientific on paper but falls apart in real world conditions unless you're talking about specific circumstances nobody brings up. Here's the thing nobody mentions though - moisture. Filler rods sit around in shops and trucks picking up humidity, and that little bit of preheat can burn off surface moisture that causes hydrogen cracking in certain base metals. Seattle's not exactly dry either with all that rain, so maybe those old timers were onto something for your neck of the woods even if it seems unnecessary for your standard mild steel jobs. Still, for most common work in a garage or yard, I agree it's probably overkill unless you're chasing some very specific quality standard.

jenny_hall10d ago

You make a really solid point about moisture, especially in a place like Seattle where stuff just never seems to fully dry out. Preheating filler rod for that reason alone makes a lot more sense when you frame it that way, @the_xena, even if it feels like an extra step nobody wants to bother with.