Welding T304 Metal Decking

[AUCE98]

I have a client that wants to replace a roof with T304 3N metal decking. They need to comply with FM Global attachment requirements, thus requires being welded. Are there any concerns of welding T304 to A992 with puddle weld attachments? I am concerned with welding dissimilar metals.

AUCE98

 

[kingnero]

Dissimilar welding is commonly done and qualitative (usually with a 309 filler metal), however there are other, more significant factors to take into consideration (like different coeff. of expansion, and galvanic corrosion).

 

[r13]

I suggest to post this question on the "Welding" forum to get more opinions.

 

[EdStainless]

I guess that my first question is Why?
What will be above and below this deck?

The SS will have a thermal expansion roughly double that of steel.
If there is moisture then accelerated local corrosion of the steel is a real possibility.
And the risk of corrosion to the SS from trapped moisture as well.
Lots of potential issues.

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P.E. Metallurgy

 

[Ron]

A properly done puddle weld does not depend entirely on the perimeter fusion with the sheet metal. A puddle weld is required to be "reinforced" meaning the puddle is a concave profile that extends over the perimeter of the initial blow through hole. This creates an attachment much like a screw head holding the decking down in addition to the perimeter fusion.