Corrosion in SS316

[metboss]

Hi all,

We have API 6A high pressure Gate Valve cladded with Inco 625 internal cladding. Seat pocket and Gate material is SS 316. My question is “ are we oaky to use Inco 625 and SS 316 combination in galvanic corrosion point of view ? Any localized corrosion ?
Service medium is Water.

Thanks

 

[EdStainless]

How bad is the water? If you have chlorides then you risk pitting/crevice corrosion in the 316.
This isn't because of the 625, it is just that 316 has mediocre pitting resistance.


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P.E. Metallurgy, Plymouth Tube

 

[metboss]

Water is tested & free Chlorines. It is for water injection wells. Our concern is on galvanic corrosion between SS 316 & Inco 625 when service medium is water (free from chlorides).

Regards

 

[EdStainless]

If the 316 will not corrode on it's own then the 625 will not cause galvanic issues.

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P.E. Metallurgy, Plymouth Tube

 

[metboss]

Thanks for your feedback.

Regards

 

[metboss]

This is for water injection well. Although water is being tested, presence/effect of chlorides cannot be ruled out due to contamination with other fluids during in service.

In such cases, if SS 316 corrodes by its own due chloride presence in water, then what is the further impact ?

1) Will combination of dissimilar metal (SS 316 & Inco 625) further aggravate pitting corrosion of SS 316 in chloride presence?

2) Any control measures to mitigate such problems ?

Regards