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4
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HgTX
Civil/Environmental
- Aug 3, 2004
- 3,722
"You keep using that word. I do not think it means what you think it means." (Princess Bride)
I am posting this in this particular forum because bridge welding is more likely than structural welding to have long machine welds.
Almost every set of plans I see requires E70XX or E7018 electrodes. But just because your undergraduate steel design textbook used E70XX electrodes in the design example does not mean that is all there is to welding with 70-ksi electrodes.
Designers seem to intend "E70XX" to generically mean "filler metal with a minimum tensile strength of 70 ksi". But it does not mean that. E70XX means something very specific. It means filler metal with a minimum tensile strength of 70 ksi, welded by the shielded metal arc welding process. That is stick welding. With rods. Manually. With stops and starts every foot or so.
If you want the fabricator to be able to use any machine or semi-automatic wire-fed process such as submerged arc welding, flux-cored arc welding, etc., you cannot say "E70XX". Moreover, if you are designing to a specification that requires SAW for certain types of joints (AREMA and certain DOTs), you create a spec conflict by using that term. If you are using weathering steel, the corresponding weathering filler metal is in fact 80 ksi (a side effect of the alloys, not because more strength is needed), and if you require E70XX for a weathering steel structure you have now guaranteed non-weathering properties for your welds.
The best way to get the weld metal you want is to call for filler metal of matching strength to the base metal; this is covered very well in the AWS D1.1 and D1.5 welding codes. Otherwise you can talk about the minimum required weld metal tensile strength.
But don't say "E7018". The fact that you've gotten away with it so far just means people have been ignoring you. But "we knew what they meant" is not the optimal way to go about one's business.
Rant over. Thank you for your time.
Hg
I am posting this in this particular forum because bridge welding is more likely than structural welding to have long machine welds.
Almost every set of plans I see requires E70XX or E7018 electrodes. But just because your undergraduate steel design textbook used E70XX electrodes in the design example does not mean that is all there is to welding with 70-ksi electrodes.
Designers seem to intend "E70XX" to generically mean "filler metal with a minimum tensile strength of 70 ksi". But it does not mean that. E70XX means something very specific. It means filler metal with a minimum tensile strength of 70 ksi, welded by the shielded metal arc welding process. That is stick welding. With rods. Manually. With stops and starts every foot or so.
If you want the fabricator to be able to use any machine or semi-automatic wire-fed process such as submerged arc welding, flux-cored arc welding, etc., you cannot say "E70XX". Moreover, if you are designing to a specification that requires SAW for certain types of joints (AREMA and certain DOTs), you create a spec conflict by using that term. If you are using weathering steel, the corresponding weathering filler metal is in fact 80 ksi (a side effect of the alloys, not because more strength is needed), and if you require E70XX for a weathering steel structure you have now guaranteed non-weathering properties for your welds.
The best way to get the weld metal you want is to call for filler metal of matching strength to the base metal; this is covered very well in the AWS D1.1 and D1.5 welding codes. Otherwise you can talk about the minimum required weld metal tensile strength.
But don't say "E7018". The fact that you've gotten away with it so far just means people have been ignoring you. But "we knew what they meant" is not the optimal way to go about one's business.
Rant over. Thank you for your time.
Hg