the_jason•17d agoMost Upvoted

Old timer at the union hall changed my mind about preheating pipe before welding

I used to skip preheating on anything under 3/4 inch thick, just figured it was a waste of time. This guy named Mike at Local 74 in Gary sat me down and showed me his phone with a crack he found on a job where nobody preheated. He said, "You might save 10 minutes now but you'll spend 2 hours grinding out a repair later." Next day I tried it on a 1/2 inch plate and the weld laid in way smoother than usual. I've been doing it ever since and my x-ray pass rate went up to 95 percent. Has anyone else had a similar wake-up call from an old timer?

2 comments

2 Comments

vera_campbell17d agoMost Upvoted

That's a solid lesson right there. Hearing it straight from a guy who's seen the cracks form really drives it home. On anything over 1/4 inch I'd say it's cheap insurance, especially if you're running 7018 rod.

tyler_bell17d ago

@vera_campbell Actually, 7018 is a low-hydrogen rod, so it needs preheat more than it needs a hot pass for crack prevention.