weld connections - 1920s steel

huangyhg

weld connections - 1920's steel
i have a project with structural steel built possibly in the 1920's, not really certain exactly when.  how can i determine if the steel is weldable?  
check out our whitepaper library.
i am sure that someone has asked this question before. check the past threads for anything on this topic.
take a coupon and send it to a testing lab to determine weldability. the coupon must be removed in such a way as to not modify its properties.
how large does this coupon need to be?  
i intend on welding the bottom flange of a 15" x 60 plf section erected in 1907, to the top flange of a new section to create a built-up section for an existing facility.
i would do this before cutting out a piece to test.
a quick test to see if it is readily weldable is to make a one side fillet weld,7018 electrode, a 1/4" 2"x2" tab in an inconspicuous place and try to forcibly remove it.
try first in the hard direction, hitting one time on the weld side. then hit it from the easy side. it shouldn't break out the hard way. the weld should fail hitting from the easy side.