Definition of "Root Pass"

By ssbn727 (*****)

Date 03-07-2014 08:00

According to AWS 3.0 2001 (Yeah, yeah! I know it's an old out of date version but, it's all I had!): "Root Pass" - A weld pass made to produce a root bead (page 32).... Well, that doesn't tell us much so, let's dig further...

"root" - A nonstandard term when used for "joint root" or "weld root (page 32). Hmmm... "root bead" okay let's look that up...

"root bead" - A weld bead that extends into or includes part or all of the joint root (page 32)... I'm still not satisfied are you?

So, let's look at "joint root" - That portion of a joint to be welded where the members approach closest to each other. In cross section, the joint root may be either a point, a line, or an area. See figure 4 (page 22)... And "joint" is defined as: The junction of members or the edges of members that are to be joined or have been joined (page 22)...
Now we're getting somewhere... So let's go see how a "weld root" is defined...

"weld root" - The points, shown in cross section, at which the weld metal intersects the base metal and extends furthest into the weld joint (page 44). See figures 24(B)-(E), 24(H)-(K), 24(M)-(P)... Confused? You shouldn't be by now so, that's how I go about understanding what the AWS defines "root pass."
So, if you want to use your own words to better describe what a "root pass" really means, then go for it! :yell:

Besides, I'm tired and am up way past my bed time friend so, I apologize for leaving the rest to you... I hope this helped somewhat. :wink:

Respectfully,
Henry

By supermoto (***)

Date 03-07-2014 10:45

Thank you for taking the time to look into this for me. The reason I'm asking is because we are making some CJPs and a majority of inspectors are in agreement that a "Root Weld" can be more than one layer/pass. This is the first time over heard someone interpret it that way, I'm used the first single pass being a "Root Weld"

By js55

Date 03-07-2014 14:18

In my opinion if a single bead ties in both members simultaneously then it will not be more than one layer. If you are building out from one member to another it still is not more than one layer, though it is more than one bead. And so in my opinion a root cannot be more than one layer.

By js55

Date 03-07-2014 14:20

Henry,
The way these definitions are approached sometimes defies common sense. There is an element of tautology in all of it.

By supermoto (***)

Date 03-07-2014 15:06

At the end of the day my "opinion" doesn't count even though I agree with js55 that a single/pass layer is the only acceptable "Root Weld". I am just looking for the facts from industry standards. Some people are taught information and don't question it because that is what everyone else is saying but to investigate and CYA is a much better practice. The "Root Weld" as I know it as a single pass/layer is an industry standard but I'm on a current project that has a Tee CJP joint with a double bevel and they are putting in 2 Root Welds from one side to have enough material to backgouge. The issue is both root and back gouge gets PT examination and signed off as acceptable as a single "Root Weld" for VT and PT.

By js55

Date 03-07-2014 15:45

super,
If the first pass/bead fuses both components then the second pass is not a root. Adding material for a backgouge does not make it a root.