Ceramic backing for Duplex Stainless Steel

[Oscarvs]

Sirs,
Please if somebody could send me information or comments about the advantages or disadvantages of use the ceramic backing for welding on duplex stainless steel (ASTM A240 type 2304). We construct storage tanks for mining industry and the weld for both sides are possible, but we thinking use ceramic backing for reduce the heat input on HAZ, because the heat is harmful for the duplex stainless steel. The process used is FCAW process with gas shielding 100% CO2.

 

[metengr]

Oscarvs;
Ceramic backing or even using ceramic backing tape is commonly used for welding from one side only versus two sides. What is the storage tank plate thickness range? I don't see why you can't weld from one side, back grind and (if necessary) add weld metal to ensure full penetration? If a proper root is pulled from one side, you should not need to add a significant amount of weld metal from the opposite side.

Try the ceramic backing tape and evaluate the results regarding welder productivity.

 

[Oscarvs]

Metengr,
I know that the heat is harmful for duplex stainless steel, so I want minimize the heat input on the weld seam. With ceramic backing, I avoid the heat input for both back grind and back weld.

 

[metengr]

I agree. You also control heat input with interpass temperature. For duplex stainless steel, your interpass temperature should be below 300 deg F. I really don't see a problem with welding from both sides provided you follow strict interpass temperature control.

 

[weldtek]

Oscarvs,
As metengr says, done properly, two sided welds on duplex can be made without compromising the HAZ's. If you do plan to use ceramic backing, proper joint design is essential because you could actually create a situation where it's more difficult to maintain the desired balance.