Hi Gents, What could be the reas

[Mohsen_81]

Hi Gents,

What could be the reason and solution for the corrosion in the below photo?
The wall of electric equipment, nameplate, and lock all are 316L (material certificates approved valid for 1.4401/1.4404) and the weld filler is 316Lsi(1.4430).
The equipment is just received on-site and not installed yet (means new)

Thanks

 

[The Obturator]

It can be something as simple as contaminated water dripping over the area. This can happen especially if there is a carbon steel component above the area. It can even be due to someone unwittingly cleaning the area with a wire brush that was previously used on carbon steel. It looks like more of a surface contamination rather than deeper corrossion, but it needs a proper clean up.

*** Per ISO-4126, the generic term 'Safety Valve' is used regardless of application or design ***

*** 'Pressure-relief Valve' is the equivalent ASME/API term ***

 

[LittleInch]

Looks like the old wire brush / powered brush or grinding disc steel contamination to me.

Clean it off with a stainless steel brush.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[dik]

...and let us know if it works.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[EdStainless]

SS wire brush or clean abrasive flap wheel.
Then get a tube of RedOne or a similar pickling paste and use it to clean those areas.
The welders likely did a poor job of shielding the welds and they were heavily heat tinted.
Then to add insult to injury they either cleaned with carbon steel brushes, or SS or abrasives that had been used on carbon steel.
There is iron embedded in the surface and likely also scale from the welds.

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[dik]

I seem to recall from an earlier posting that you can use Head and Shoulders white shampoo for testing fdr ferrous contamination.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[EdStainless]

Yes, it is a great shortcut method.
White Head & Shoulders wiped onto the clean surface. (I have seen a paint roller used for large areas)
Keep it damp by gently misting with distilled water occasionally.
And over a couple of hours you will see if you cleaning worked.
If it didn't get it free from iron you will get light blue spots forming.

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[dik]

I haven't seen it used, but tried it and is seems to be an excellent 'indicator'. I don't know how sensitive it is, but I suspect it's very sensitive. On one sample I intentionally used a dry Q-tip and just a tiny bit... I picked it up really well. I don't recall who mentioned it, but it was novel and I had to try it.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[EdStainless]

I used it inside of a large process tank once. Really impressed the customer.

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[Compositepro]

This looks like rust staining. You can get it on plastic or porcelain surfaces, too. In the picture,it is seen heaviest in areas that are protected from abrasion and wear. So these are deposits, not corrosion. Where I typically see it is where water containing iron is allowed to sit exposed to air.

 

Just don't use it in the shower, H&S is disgusting stuff.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[mfgenggear]

Improper cleaning procedure, and not passivated. contact with carbon based steels

 

[dik]

But, it's a great indicator of ferric contamination...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[desertfox]

Hi

I think I would suspect that the material isn’t what it’s claimed to be, the amount of rust suggests that it’s carbon steel. Another thought it might be if it is stainless that the welding as depleted the area of chrome in which case the areas around the welds will rust, what does the manufacturer say?

See the link below for corrosion of stainless steel

https://cougartron.com/blog/why-does-stainless-steel-rust/

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[EdStainless]

It is stainless alright, just poor weld shielding and clean up.
This is very common.
The only thing more common is seeing SS artwork that was very carefully made and cleaned, and then installed by lifting with steel chains.
Leaving a series rust dash marks across it.

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P.E. Metallurgy, consulting work welcomed