Welding SS 316 to SS 316 L corrosion issue?

[AarnoudO]

Hi,

My company sells SS316 valves (bought) which get welded to SS316L weld neck flanges which we manufature ourselves from bar-stock.

A client of ours questions our welding SS316 to SS316L.
This should have a higher risk of corrosion.
They suggest it is necassary to use SS316L/SS316L.

I think we are ok because we never saw any problems with our product, but I don not realy know the actual difference between the SS316L/SS316L weld and the SS316/SS316L weld.
I know SS316L is weld quality and has a carbon content of max. 0.03%. But can someone please help me understand why someone would think that a system containing a SS316/SS316L weld is of less corrosion resistance than a system containing SS316 and SS316L but NO SS316/SS316L welds?

Your help would be greatly appreciated,

 

[stanweld]

Welding on the 316 side of the joint provides a greater chance of sensitization. Depending on the environment, there is a greater potential for intergrannular corrosion to occur in the HAZ of the 316.

 

[EdStainless]

In order to know if you are at risk you should do two things.
1. Check the actual C content of the 316 parts
2. Carry out some A262 testing

If you are interested in doing these we can provide further information.

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Plymouth Tube

 

[strider6]

316L is used 'cause it reduced the likelihood to have sensitization and following corrosion. another way to reduced the sensitization effect is to make a solution annealing heat tratment that redissolve the cr carbide and restore the corrosion resistance of the SS.
even a sensitized SS can be used in milder corrosive environemnts. I think you have to define the enviroments in and then if it's possible to make a solution annealing of the weld.

http://www.stainless-steel-world.net/pdf/11007.pdf

http://www.corrosionist.com/Materials_Stainless_Steel_Welding.htm

S

Corrosion Prevention & Corrosion Control

 

[EdStainless]

One issue to be aware of is that sensitized 300 SS is much more prone to chloride stress cracking than 'clean' material.

If these are thin parts that cool quickly and the carbon level isn't too high then everything may be fine.
At 0.05% C you have about 5 min to get below 800F to prevent sensitization.

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Plymouth Tube

 

[antmann2005]

check thermal expansion...filler material...passivate if at all required.