Mild to Stainless Weld Considerations

[TurdHerd]

I haven't been able to find yet in my searching exactly what i'm looking for, I am trying to determine what factors I should consider in designing a weld between A36 and 304 SS. I have a welded connection between a pipe and blind flange, both currently A36 steel, using E70XX weld rod, which has performed well for us for years. I am changing the flange to 304 SS to bolt to another stainless plate, so I will need to change the filler material to E309 because of the dissimilar metals, but is there any reason to assume that this weld will be any weaker than the original weld?

Thanks for the help!

 

[thaidavid40]

Why not keep the A36 flange, and use a dielectric flange kit?
Dave

Thaidavid

 

[metengr]

No. If you go the weld route, this is a dissimilar metal weld and the E309 stainless steel weld metal, will match the 304 stainless steel base metal strength. The E309 as-deposited will be above 80 Ksi minimum, per SFA 5.4 Table 6 (All Weld Metal Strength).

 

[gtaw]

The one thing you might consider is galvanic corrosion due to the use of dissimilar metals in the presence of an electrolyte.

If there is thermal cycling, the opportunity for low cycle thermal fatigue should be considered.

Best regards - Al

 

[TurdHerd]

Thanks for the replies everyone, I appreciate the advice. I will explore the dielectric flange kit, that might be helpful.

Thermal cycling shouldn't be an issue, and I plan to have all exposed surfaces coated with epoxy paint to prevent galvanic corrosion.

 

[EdStainless]

If you are coating it then why bother with stainless?


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P.E. Metallurgy, Plymouth Tube

 

[TurdHerd]

EdStainless, My pipe/flange will be coated but the plate I'm connecting to will be stainless. So I'm trying to avoid having the machined face of my A36 flange in direct contact with a 304 SS plate, it will be submerged.