What is happening here?

Question

What is happening here?

SteveWag (Civil/Environmental)

(OP)

3 Apr 14 14:32

This is a one month old sewage screening device. It is in an enclosed rated area and it's not pleasant, but not as nasty as most headworks. I have used 304 with 316 fasteners for years for this application for years and never saw anything like this. There was no welding done during or after erection.
Steve

http://files.engineering.com/getfile.aspx?folder=06b1bc7c-7d04-4a2b-98e0-84

SteveWag (Civil/Environmental) · Answer 1 · 2014-04-03 14:33:30

Photo 2

http://files.engineering.com/getfile.aspx?folder=27a442b8-a6a0-41fa-b1ae-56

SteveWag (Civil/Environmental) · Answer 2 · 2014-04-03 14:34:12

Photo 3

http://files.engineering.com/getfile.aspx?folder=497bc447-5783-4d04-9e9f-62

SteveWag (Civil/Environmental) · Answer 3 · 2014-04-03 14:34:54

Photo 4

http://files.engineering.com/getfile.aspx?folder=a453e746-17ea-493f-a72e-ae

SteveWag (Civil/Environmental) · Answer 4 · 2014-04-03 14:35:26

Photo 5

http://files.engineering.com/getfile.aspx?folder=0ab3ee89-671a-4be9-bea8-a4

SteveWag (Civil/Environmental) · Answer 5 · 2014-04-03 14:36:17

Photo 6

http://files.engineering.com/getfile.aspx?folder=d7a55926-815f-446d-b012-ee

SteveWag (Civil/Environmental) · Answer 6 · 2014-04-03 14:37:09

Photo 7

Thanks guys !!!!

http://files.engineering.com/getfile.aspx?folder=c976cd6c-7133-4f0d-8c4d-b8

weldstan (Materials) · Answer 7 · 2014-04-03 15:04:52

Looks like iron contamination (rusting) and crevice corrosion at bolting.

berkshire (Aeronautics) · Answer 8 · 2014-04-03 17:53:05

Was this part fabricated in a shop with other metals i.e. steel being fabricated?
This looks like stray iron contamination.
B.E.

You are judged not by what you know, but by what you can do.

tbuelna (Aerospace) · Answer 9 · 2014-04-04 00:49:41

Maybe just surface stains. How were the surfaces cleaned before the photos were taken?

SteveWag (Civil/Environmental) · Answer 10 · 2014-04-04 10:15:37

I am pretty sure it is shop contamination. The device erection/start-up was supervised by the shop head man and in passing I remember him saying that a lot of new workers had just been added. And, for a normally slow to respond company, they are sending a couple of guys to do on-site pickling/passivation next week (I’m in PA they in FL).
Thanks
Steve

EdStainless (Materials) · Answer 11 · 2014-04-04 16:43:58

Fe contamination.
#3 looks like weld splatter from nearby steel welding
#4 looks like someone used a brush or wheel that had been used on steel.
and so on

What concerns me are the bolts. Will they remove the bolts, clean, and then install new hardware (that has been passivated)?
If they pickle with bolts in place they will only get acid into the joints, and they may cause serious corrosion damage.
This could be true of all mechanical joints. Getting them clean in one thing, properly rinsed can be another issue.

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What is happening here?