7018 overhead 3/8 plate test questions.

Date 03-27-2014 19:34

Trying to take the easy way out. I will try to find my old specs from the test I did years ago but thought I'd ask here first. I know its pretty basic. I have held the verticle up,and mig overhead, and flux core overhead, and a ua 13 pipe welding cert. Its just been awhile and I have been welding on sheetmetal for the last few years. What size rod, amperage should I be looking at for a 7018 smaw 3/8 plate overhead with backer. Three passes I was told. Sheet metal worker by trade but the boilermakers need some welders. Thanks for any help.

By abrahamx (*)

Date 03-27-2014 22:49

eh, I beat you to it. Was worth a try I guess. Thanks anyway and happy welding.

By pipewelder_1999 (****)

Date 03-28-2014 11:13 Edited 03-28-2014 12:03

There is no "best" electrode. I am not sure about the plate test because I have only tested on the 2" super coupon. But when I have I have asked if I could use whatever size electrode I wanted. I would use 3/32 over the GTAW root pass and then 1/8 for the remainder.

For the plate test I have had students go test and some of than used 3/32 and some 1/8.

Here are my thoughts on the selection.

3/32 are easier to weld with and starts have less of a tendency to hump up.

1/8 are much more sensitive to the amperage setting than 3/32. This is most noticed when welding vert. Too high or too low makes 1/8 difficult to control.

1/8 allow me to go farther without a start stop. This is especially useful if you happen to be running out of 3/32 at the area where the bends will come from.

The less times you have staylrts and stops the less likely to have defects from the starts and stops.

The 1/8 electrodes will be more likely to produce more convexity. Welding over the previously deposited beads that may be humped up can increase the likelihood for fusion related defects.

I have always tested with 1/8 on plate and was surprised when I went to my 1st common arc test and saw people using 3/32.

So what did you find out on your own. ?

Have a great day.

Gerald