Weld Seem Strengths.?
Hello,
Let's assume we have two parallel 3' aluminum 1.3" OD, .25" wall thickness tubes. There is a 2' .5" OD .25" wall thickness tube below the two 3' tubes intersecting them on one end. The result is a U shape with the 2' tube overlapping below the other two.
Now let's assume we have a 2' 1" OD .25" wall thickness tube overlapping ABOVE the two 3' pipes, but 5" back from the edge where the thinner tube overlaps.
These tubes are all welded together. The aluminum is 6061 T6 Schedule 40.
Could someone comment as to the forces (vertical and lateral) these welds could be expected to withstand? Are we looking at a level a person could exert, or into the hundreds of pounds? I am simply talking about the welds, not the tubing.
Thanks
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The filler metal is answer, but you didn't give ANY specs on the filler metal! So, with that being said,I cannot tell you the answer to your question. HOWEVER, your tubing should withstand 45,000 pounds of pressure per square inch. If you tell me what filler metal you were using, I can tell you what the welding will be able to withstand. The first 2 numbers in your filler metal will indicate tensile strength multiplied by 1000. For example a 7018 rod tells me the following: 70= 70,000 psi tensile strength, how much the weld will hold. The 1 tells me it can weld in all positions, flat, virtical, horizontal and overhead. The 8 tells me that its a low hydrogen rod.
I must also add that this depends on the soundness of the weld metal deposited. If there are defects in the weld such as undercut, porosity etc, that will affect its strength. There are other variables as well, but I'm not getting into that.
The previous posters are mistaken.
The weakest part of any weld is in the "Heat Affected Zone" (H.A.Z.) around the weld, not the weld itself. This is especially true with aluminum. T
Note: The "-T6" suffix after 6061 indicates heat treated material.
===> Welds on heat treated Al alloys like 6061 series can be expected to be SIGNIFICANTLY WEAKER than the parent metal.
The heat of welding destroys the heat treatment in the H.A.Z. and may result in greater than 60% loss of strength there.
Welds on aluminum are also notoriously prone to cracks, unlike steels. The reasons for this are complex and don't bear discussion.
I'm not sure I understand what you mean by "overlapping above" and "overlapping below." I can't really give you an idea how strong the joints would be unless you're much more specific.
Are you talking about simply laying the pipes on top of one another and depositing a small amount of weld around the contact point? That's a bad idea. You'd have a far stronger joint by drilling a hole through both pipes and bolting them together in that configuration.
I'm no engineer so can't specify strengths but, typically welds are held to be stronger than the than the components that they hold. Working with high pressure gases in welded stainless steel tubing I have never seen a weld give way although I have seen a tube rupture.
This also depends upon the type and quality of the welds. If the welding was done by an experienced welder who works with aluminum the welds will be stronger than if the welds are done by an experienced welder who does not work with aluminum.
Aluminum welding is a specialized trade.