TIG question

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I'm new to TIG.I am going to TIG some steel.  The pieces are 3/16" hot-rolled plate to 3/16" hot-rolled plate (at right angles) and 3/16" hot-rolled plate to 1.5" X .083" square tubing.  What surface preparation do you recommend?  I grinded the mill scale off the hot-rolled and was planning on cleaning the oil off the tubing with brake cleaner.Should I do anything else?  If so, [email protected]
Reply:Take the scale off the tubing as well.  The little 3m sanding disks work well, so do the fine grit flap disks.  Clean with acetone.  You shouldn't need to take much off of the tubing at all.  Be sure to wipe the inside of the tube ends as well, and the plate after grinding.
Reply:The tube is bright (e.g. not hot rolled).  Do I still need to grind it?
Reply:Even if the tubing does not have a heavy scale on it like HR, it still has a scale.  You can get by without taking it down to bright metal, but I never chance it.  Take a look at this thread for how it should be prepped prior to TIG welding:http://weldingweb.com/vbb/showthread.php?t=28660