Stainless Manifold Repair
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Stainless Manifold Repair
I have a stainless manifold and it's cracked twice now. The first time it cracked the cracks were welded back up, and some additional metal was added to increase the strength.
Now it is cracked again, in different places.
I was thinking it needed relief cuts, but some hunting around here suggests that those are only required on the cast manifolds. I'm also afraid that if I make any relief cuts, the manifold won't seal against the head anymore.
Do I just need to re-weld the cracks again and try to get better penetration? Add more filler wire? Or do I need to do something to change the stresses?
Now it is cracked again, in different places.
I was thinking it needed relief cuts, but some hunting around here suggests that those are only required on the cast manifolds. I'm also afraid that if I make any relief cuts, the manifold won't seal against the head anymore.
Do I just need to re-weld the cracks again and try to get better penetration? Add more filler wire? Or do I need to do something to change the stresses?
#2
Was it bolted to a flat plate the first or second time it was repaired?
I would recommend grinding out the majority of the weld that is cracked beyond the cracked section, beveling both sides of the gap, lay a root pass with purge than cover pass.
I would recommend grinding out the majority of the weld that is cracked beyond the cracked section, beveling both sides of the gap, lay a root pass with purge than cover pass.
Last edited by Zsanz; 07-17-2018 at 07:40 PM. Reason: bcuzItypegewd
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What wall thickness is that manifold.
Got any closer pictures? In the last picture is the crack in the middle of the weld?
Welds look a little undercut.
What material and filler?
Got any closer pictures? In the last picture is the crack in the middle of the weld?
Welds look a little undercut.
What material and filler?
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The manifold is stainless, I'm assuming 304 but I don't know for sure. I assume the wire is the same, but again that is just my assumption. The material is pretty thick; they are "weld els" but I'm not sure if they are a standard thickness or not.
The cracks are all down the middle of the welds.
What is "undercut" in regards to the welds?
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I'm learning to weld at work, so I will be getting help from one of the good welders there when I fix this. I'm not sure we can purge, but I will ask. I do know we only use TIG for stainless steel though.
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This sucks, sorry skidude.
304ss, schedule 40, 308 filler. I bolt the manifold to a spare head when I weld them, initially and when I fixed it the first time/added those square support patch things.
I wouldn't worry about the head not sealing if you make relief cuts, especially if you bolt the flange to something flat when you reweld it.
Like noted already, grind out as much of the crack as you can giving you a little channel to add new filler. Go past the current crack somewhat. Back purge with argon can't hurt, same for adding more square overlaps.
304ss, schedule 40, 308 filler. I bolt the manifold to a spare head when I weld them, initially and when I fixed it the first time/added those square support patch things.
I wouldn't worry about the head not sealing if you make relief cuts, especially if you bolt the flange to something flat when you reweld it.
Like noted already, grind out as much of the crack as you can giving you a little channel to add new filler. Go past the current crack somewhat. Back purge with argon can't hurt, same for adding more square overlaps.
Last edited by TurboTim; 07-18-2018 at 10:47 AM.
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This sucks, sorry skidude.
304ss, schedule 40, 309 filler. I bolt the manifold to a spare head when I weld them, initially and when I fixed it the first time/added those square support patch things.
I wouldn't worry about the head not sealing if you make relief cuts, especially if you bolt the flange to something flat when you reweld it.
Like noted already, grind out as much of the crack as you can giving you a little channel to add new filler. Go past the current crack somewhat. Back purge with argon can't hurt, same for adding more square overlaps.
304ss, schedule 40, 309 filler. I bolt the manifold to a spare head when I weld them, initially and when I fixed it the first time/added those square support patch things.
I wouldn't worry about the head not sealing if you make relief cuts, especially if you bolt the flange to something flat when you reweld it.
Like noted already, grind out as much of the crack as you can giving you a little channel to add new filler. Go past the current crack somewhat. Back purge with argon can't hurt, same for adding more square overlaps.
Would you recommend fixing the cracks then cutting the flange, or cutting the flange before I weld the cracks? I'm thinking I should weld it first.
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Why 309 filler? I've always used 308 or 304-304.
If that was picture is a crack in the weld that's unusual. Most of the time the cracks appear next to the weld in the haz.
If that was picture is a crack in the weld that's unusual. Most of the time the cracks appear next to the weld in the haz.
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If you are going to cut the flange, I would absolutely do so prior to bolting the manifold to a flat plate and re-welding it. This will put the least static stress on the welds after you bolt it to the head.
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I think 309 is acceptable for stainless to stainless. But it's usually the go to "different metals" filler.
Skidude. Can you post closer pictures of the cracks?
Undercut is when the weld is slightly under the surface of the 2 joining tubes.
But I didn't realize Tim was the one who built that manifold, and he knows more about welding than I do for sure.
Skidude. Can you post closer pictures of the cracks?
Undercut is when the weld is slightly under the surface of the 2 joining tubes.
But I didn't realize Tim was the one who built that manifold, and he knows more about welding than I do for sure.
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I don't know much about welding, other than the more I step on the pedal, the hotter my hands get.
So my welds are funny, they crack thru the weld instead of the HAZ My most recent header for the VP's boat routinely cracks straight thru the reinforcement patch. Crazy.
So my welds are funny, they crack thru the weld instead of the HAZ My most recent header for the VP's boat routinely cracks straight thru the reinforcement patch. Crazy.
#18
1) If its 304, use ER308 or 308L filler.
2) Do not preheat. There is no benefit to preheating an austenitic stainless steel, only detriment.
3) You need to purge the weld root.
4) Your welds are underfilled, and the spacing of your "dabs" of filler is creating pinholes/craters from shrinkage. This is a highly restrained piece, so it's going to crack down the centerline accordingly.
5) You need to completely excavate the cracks for repair, and a bit beyond. Every butt weld there needs additional weld metal. Honestly, given the simplicity of the piece and the fact that it can't be properly repaired without removing the flange, I think you'd be time/effort ahead by re-fabricating the entire piece.
2) Do not preheat. There is no benefit to preheating an austenitic stainless steel, only detriment.
3) You need to purge the weld root.
4) Your welds are underfilled, and the spacing of your "dabs" of filler is creating pinholes/craters from shrinkage. This is a highly restrained piece, so it's going to crack down the centerline accordingly.
5) You need to completely excavate the cracks for repair, and a bit beyond. Every butt weld there needs additional weld metal. Honestly, given the simplicity of the piece and the fact that it can't be properly repaired without removing the flange, I think you'd be time/effort ahead by re-fabricating the entire piece.
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