Weld penetration

After first selecting the proper joint type from the 5 basics, (butt, tee, lap, corner, edge) joint prep becomes a factor or not. A fillet weld on a tee joint for example will most often require no edge prep grooving.

The type of joint chosen dictates the type of edge prep and the degree of penetration required for a sound joint. In structural welding the AWS has structural welding codes that spell out the various requirements.

The spacing between two pieces of a joint is referred to as the root opening. The root face is the edge that is not beveled. The width of the root opening and the angle of the bevel (on joints requiring a bevel) is decided upon depending on the accessibility of the joint, the joint design, and material thickness. Can you get to one side or both? Are you using a backing plate for instance?

In general as the materials groove angle decreases, the root opening increases. Also, in very general terms, in material 1/4" thick or more, joint edge prep is required with the exception of the fillet weld mentioned previously. (On square groove joints, 1/4" is the maximum thickness where full root penetration can be achieved when both sides arc accessible.)

You asked some great questions that I wish I could answer but I can't. I'm on too much medication to think straight at this time. It's he11 knowing that you have it up there somewhere but can't spit it out.

Hopeful that someone else can chime in here and give you some good answers.

T_Bone

There were excellant replys to your post. My head is fairly clear tonight so let me give a reply.

Yes I was referring to base metal penetration on my last post.

As stated, joint design has everything to do with penetration. As a general rule anything over 1/4" base metal thickness needs a bevel of approx. 45 degrees. Thats 22.5 degrees bevel on each piece on a groove weld joint. Root face should be limited to 1/8" maxmium with a 1/8" maxmium root opening. Some joint designs require less bevel and some joints require more. This would also be effected by the welding process selected.

Now that I gave a general rule of thumb, let me blow that therory out of the water with this example. We have a 1/4" square butt joint weld with 100% joint penetration required with the back of the joint not accessible. As stated above we don't need a bevel, and root opening will be 1/8" and we will use a 1/8" 6010 electrode a very deep penetrating electrode. Using 1/8" 6010 DCEP there would be no way we would achieve 100% penetration without a bevel on this joint design with out back gouging the weld which we can not do because it's not accessible. We could however achieve 100% penetration with a 30 degree beveled joint design or by using a backing plate with a 1/4" root opening.

As a welder gains experience, it will be apparent when more or less bevel is needed for a pictular joint design for 100% penetration weld no matter what the joint design is.

Is a 100% penetration weld needed all the time? Nope, as a fillet joint weld would be good example.

The AWS code book has several pages of joint design spec's so it's not possible to cover all of them in this post.

T_Bone

Well it's from the medication I'm taking, I think. Seams like the short term memory is being effected as I read some of my posts and I know I wrote it but it doesn't register as me saying the content of the post. Had to look on a form tonight to spell my first name. I couldn't remember if it had 1 n or 2 n's to spell Kenneth. Wife says it's time to see the Doctor again.
Anyway kinda spooky on this end so thats why I quit posting so much as I don't want to give out any wrong info.

Thanks for asking
T_Bone