Mark Feddersen wrote:

I did not add the weld to the .005 wrapper, but I have no knowledge if this is correct. I remember being worried that if I scribed a weld line in the .005 styrene wrapper, it would be weakened and when glued to the body it would not curve smoothly, but rather leave a slight peak. Today, you can add an Archer weld line if need be.

I could only find a couple of top-down views of jacketed tank cars in Ed Kaminski's books, but none showed a top weld seam, so my view would be that it's not needed.
Let me take this opportunity to credit Mark for his inspiring articles in _Mainline_ all those years ago. I pored over them so many times I hardly even need the Xerox copies I made, and have had a variety of tank car projects popping up in my mind ever since. Thanks, Mark.

Tony Thompson Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705 www.signaturepress.com
(510) 540-6538; fax, (510) 540-1937; e-mail, thompson@...
Publishers of books on railroad history