welding corroded steel

huangyhg

welding corroded steel.
we have some precast concrete cloumns in which the existing column base plates have experienced various degrees of corrosion/rust.  the existing base plate is plate steel anchored and cast into the column base.  would like to weld a new base plate to the existing base plate, core out the existing anchor bolts and install new epoxy adhesive anchor bolts.  any thoughts on surface preparation of existing base plate and welding new base plate to it?
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grinding to shiny-bright material is usually all it takes. remove as much corrosion from the weld and adjacent areas.
simply cleaning the area of weld may not be sufficient. debris, rust or other foreign material at the faying surfaces may creep up on the welder during welding resulting in porosity, incomplete fusion or other weld discontinuities.
check out aws d1.1:2002, 5.15.
grinding is good but labor intensive. bead blasting is cost effective and faster if you are set up to do either.  depends a great deal on how bad the plate is corroded and how many columns you are doing.  often you will not be able to grind all the rust out to the satisfaction of the inspector.
rod
i agree with evelrod.  it will give you a better job, but you might also need to do some post-blast grinding to achieve a flat mating surface.
after you do all this, don't forget to check the plate for loss of cross-section effect on its capacity.