Welding Tips and Tricks

Why, scientifically, is a weave used instead of a straight beads on caps?

It what position are we talking about?

Like you, I'm still in school and we run weaves as caps. Many of the folks I've talked to "in the field" though run stringers. I've never asked about the scientific answer for this though, so i'll be interested in seeing the responses.

Mike

NO PHD'S on this site guy's remember!! LOL!!

Scientifically? Here's some welding (food) for thought. Let's go back to welding school. On a welding test plate 1/2" thick we start out with pass one the root. We clean it well. Pass #2 with 2 passes. Clean it well. Pass #3 three beads all passes are over lapping. Each pass you lay down has a increasing heat change designed to burn out any impurities of the pass before it. You start out with a completely cold plate and by the time you get to the final cap pass (weave Bead) most of if not all impurities from each successive pass has been burned out of the weld zone. The final cap (weave bead) has the least likelyhood of having any slag inclusions if properly executed by a skilled welder. SCIENTIFICALY!!

James L. Porter
First Class Welding & Fabrication

I am certified 1" unlimited i have passed numerous numerous tests with the stick always using stringers. ive never weaved not even on the caps.

In my class we weave the fill pass on groove welds slightly, but the cap passes are always stringer(according to our instructor). That said, I've had a few old hands tell me that if you have a spot where the puddle is not filling in where you need it to, just nudge it over slightly and get it to fill in. I have used it and it works well enough for me. Although at times it is noticeable in the finished bead.

Ive been a boilermaker for several years now but when I first tested overhead and vertical I had been running a stick for all of two days and the instructer told me to use a weave some how I passed, Ive been doing that way ever sence. I have friends that make hp steem welds on pipe and they are only allowed to use stringers

Stringers are quicker and will use less number of rods, generally speaking. I do realize this is not scientific.

in my opinion a weave bead is just another term for cover pass. it does just that, after using stringer beads to fill the beveled joint to just below flush the last pass is welded side to side just enough to "cover" the preceding passes and make a visually pleasing structurally sound cover pass.

Alot of times, its what the job is specced for. Each weld on the job is engineered to have a certain number of passes done with a certain number of rods welded a certain way. Some jobs call for stringers, some call for weave.

The strength of any weld is largely influenced by its cooling rate. The cooling rate of the stringer bead is much faster and therefore the grains are much smaller than for a weaved weld. However the cooling rate also has an effect on the HAZ which is often the weakest part of the weld. Due to the faster cooling rates of the stringer weld, there is less heat available for the growth of a HAZ, and so the HAZ of the stringer weld is narrower, giving a smaller "weaker" area and a stronger weld.

And there are other mechanical properties to consider. Stringer welds will generally be harder, less ductile and more creep resistant than weaved. I don't know about corrosion resistance or fatigue behaviour.

that's way too deep for me. i'll leave the metallurgy to the engineers.

jwmacawful wrote:that's way too deep for me. i'll leave the metallurgy to the engineers.

You can do that, but I'll tell ya what man. Every book I've read and every welder I've talked to will tell ya to learn as much metallurgy as you can. The more you know about metallurgy, the better a welder you will make. Some food for thought :)

i'll tell you what and no offense, been welding for almost forty years~ everything from splicing 4" thick "H" beams to welding high pressure steam lines and repairing cast iron, have my 1st. class welding license for over 30 years. have you ever heard the story about teaching old dogs new tricks?

hehehe. More than once.

well, there's lots of truth to it. stay safe.

btw, what kind of welding do you do and where do you do it??