RobsVette
Mechanical
- Apr 15, 2009
- 94
Ok Guys, I have a question and am hoping you guys can help. The question results from me doing something stupid, I want to see what you guys think. If I ultimately have to redo the weld joint I am willing to take responsibility for my mistakes and accept that, however I want to make sure I have a full understanding of what is required before I make a blanket statement that I need to redo a weld.
Here is the issue, we are welding a 12" x 20" piece of hollow stuctural steel (5/8" thick) to a 2" thick plate that is 4' x 4' to create a pipe support for a steam line.
The design engineer for the structure is saying that in order to carry the loads that were determined by the stress analysis, we need to be able to have a full penetration weld. (as a disclaimer: this individual by his own admission is not a welding engineer. His position is the he wants to be absolutely certain that he can count on 100% of the cross section of the tube as load carrying. ie... there are no break on discontinuities to create stess concentrations along the weld joint)
According to AWS D1.1 this is a T or Corner joint. When reviewing the pre-qualified WPSs in D1.1 none of them allow for a simple open butt joint with a 6010 root. The only thing that I can come up with is either a TC-U4A joint (which would require backing) or a BTC-P4 joint (with a 1/8" land.) This is the rout we went. Rather than try to secure backing strips I felt it would be easier to weld with the land as a partial penetration joint.
Given the very small land used (1/8") is it still acceptable to take credit for the entire 5/8" as being welded from the tube steel to the plate. My opinion would be yes, because as you weld the first passes (7018 rod was used to weld this,) you would have a good amount of penetration down into the base metal in order to join them together. I know 7018 is considered a moderate penetration rod, but I think you would still break down the metal along the land and create a good fusion along the root of the joint. I dont think it would be a 100% "X Ray quality" weld, but I do think it would acceptable in regards to the load carrying capacity of the support.
What would you guys consider on a joint like this? Would the partial penetration be acceptable or should I go back and redo the joint to make it a complete penetration. Any refences in AWS D1.1 would be helpful as well.
Please let me know if any further information is needed.
Thanks in advance for any help.
Rob
Here is the issue, we are welding a 12" x 20" piece of hollow stuctural steel (5/8" thick) to a 2" thick plate that is 4' x 4' to create a pipe support for a steam line.
The design engineer for the structure is saying that in order to carry the loads that were determined by the stress analysis, we need to be able to have a full penetration weld. (as a disclaimer: this individual by his own admission is not a welding engineer. His position is the he wants to be absolutely certain that he can count on 100% of the cross section of the tube as load carrying. ie... there are no break on discontinuities to create stess concentrations along the weld joint)
According to AWS D1.1 this is a T or Corner joint. When reviewing the pre-qualified WPSs in D1.1 none of them allow for a simple open butt joint with a 6010 root. The only thing that I can come up with is either a TC-U4A joint (which would require backing) or a BTC-P4 joint (with a 1/8" land.) This is the rout we went. Rather than try to secure backing strips I felt it would be easier to weld with the land as a partial penetration joint.
Given the very small land used (1/8") is it still acceptable to take credit for the entire 5/8" as being welded from the tube steel to the plate. My opinion would be yes, because as you weld the first passes (7018 rod was used to weld this,) you would have a good amount of penetration down into the base metal in order to join them together. I know 7018 is considered a moderate penetration rod, but I think you would still break down the metal along the land and create a good fusion along the root of the joint. I dont think it would be a 100% "X Ray quality" weld, but I do think it would acceptable in regards to the load carrying capacity of the support.
What would you guys consider on a joint like this? Would the partial penetration be acceptable or should I go back and redo the joint to make it a complete penetration. Any refences in AWS D1.1 would be helpful as well.
Please let me know if any further information is needed.
Thanks in advance for any help.
Rob
