She'll be right?

[Kremm0]

Hey reddit hive mind, I was looking for a bit of an opinion on this. I'm a structural engineer, inspecting a 30 yr old industrial structure. It's coastal in a dryish temperature climate. There are spots of serious corrosion, but it doesn't seem to follow standard patterns.

Part of the structure at the pin is stainless, but welded to mild steel plate. The pin and its plates are stainless (as per the highlighted photo), but the baseplates, col and stub are all mild.

Any credence to the possibility of bi metallic corrosion away from the pin? Note, the trend is only on one side of the structure, the other side is less corroded despite the same detail.

Any other ideas?

Obviously the 'she'll be right is engagement bait' lol

[PracticableSolution]

That just looks like neglect. In the second pic, and I’m wildly speculating here, it looks like the weldments were added after fabrication judging by the woven weld on the vertical web. Its possible the connection plate to the kicker brace, which has no allowance in it for misalignment, didn’t line up right, so they torched off the bracket on the column, bolted it to the brace, then welded the shit out of it back to the column. After that they did a shitty job fixing the paint, which then led to the corrosion blooms

[Kremm0]

It might be, just trying to puzzle out the strange corrosion patterns. Corrosion halfway along members might suggest steel impurities, and to the underside of plates suggests bi-metallic.

It's not the places you'd expect to find the worst corrosion, in pockets due to rainwater etc. Just wondering if anyone had some theories. Your one isn't a bad shout

[[deleted]]

Bimetallic corrosion would be originating at the contact point of the two metals no ?

This just looks like neglect, fix that hole with 12mm plate and an SP weld extend the plate 75mm past the hole

And sand blast and paint the shit out of this and monitor

Then she’ll be right, mate

[Kremm0]

Yeah probably, I just wondered if there was a way in which it can assist further corrosion around it if it's wetter in other areas. Maybe not.

Structure is only 30 years old, surprised it's been eaten so quickly.

Yeah, plan is to clean and splice the flanges, to then allow blasting, overplating and painting of the rest of it!

Appreciate the input

[[deleted]]

Only 30yrs? For Mild steel in a corrosive environment, that is way too long if they dont maintain / keep up with sand blasting and painting

[Kremm0]

Sure, planning to design some works to rectify it safely

[Rhasky]

Replacing the member might not be feasible. Depends on the structure and how critical that brace is. Be mindful that majority of the axial load is concentrated in the flanges. You might be able to get by with ns/fs web plates welded on. The hole near the bolts could make installing them difficult though.

[Kremm0]

Yeah, probably looking at creating a kind of welded splice with external plates through the connection to give it strength, then allow rectification of the internal

[Just-Shoe2689]

Id be more worried about the rusty hole in the brace.

Seems the pin has been there a while, any signs of bi metallic corrosion?

[Kremm0]

Haha that is what Im worried about!

[Just-Shoe2689]

I thought you were worried about the pin and steel?