Welding 316L with 308L ?

[AUSTIN316L]

Hi
We've welded 316L base metal with 308L filler (by mistake). I would like to know of any negative effects if the product is used in a potable water application, no more than room temp, static load (in the region of 20 ksi).

The product will be passivated prior to use.

 

[Metalguy]

If you TIG welded the root pass you probably have enough moly from dilution to approx. 316L on the ID. 316/L has a lot more Cl- resistance than 304/L and 308/L, so you should be OK if the Cl- is reasonably low and only on the ID.

You can have a lab. confirm the Mo level of the root pass.

"I'm that dog who saw a rainbow, only none of the other dogs believed me." from "Kate and Leopold"

 

[AUSTIN316L]

Actually the weld was MIG welded. Our lab results show up to 0.9% of Moly from Dilution of the base metal 316L.

After passivation, visually there's no signs of a difference. An overnight rinse with tap water (containing some Ch) showed no signs of corrosion. At least none I could see.

Now I'm thinking if doing a quick TIG pass with 316L filler rod would be a good idea to inject some Moly. Then of course passivate the joint as we normally would.

 

[metengr]

I agree with Metalguy. In addition, I would not bother with the TIG pass.

 

[EdStainless]

In theory the 316 cover pass would be a good idea, but I doubt that it would really help.
You may get pitting in the welds, but the risk of microstructural damage from the heat input of another pass is just as risky.
Leave it.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm