Why is your lead failing?  What is the T & P of the steam, and the diameter & wall thickness of the lead?  What is the solution you are heating?

Alternatives to lead are
1) All plastic HXers (PVDF) or Teflon.  Read the article Fluoropolymer Heat Exchangers at http://www.metalfinishing.com/WZ/MetalFinishing/guidebooks/MetalGB_FinishingPlantEngineering/000018/show/
George Fischer sells some nice PVDF units, both internal and external types:
http://www.us.piping.georgefischer.com/index.cfm?D0FD2F71A3AE4B00AA6B6C72BF427CA2

2) Teflon-coated metal HXers.  The major manufacturers all carry them; the cost is about 20-25% greater than for bare 304 SS, and then you further need to increase the area by 20%.  However, maybe more efficient than much thicker wall lead pipe.  Need to avoid scratches, of course.

3) Zirconium, tantalum, titanium or some other chemically resistant HXer.  I use Zr HXer for cooling sulfuric acid anodizing solution, and due to higher efficiency, am using a much smaller HXer than previously with lead (pipes lining nearly all the entire tank walls).  Now, only have Zr HXer on the back wall.  Due to the smaller size & weight and ease of installation, the installed cost is less than for lead, plus have more usable space.  See
http://www.tranter.com/
http://www.titanmf.com/
http://www.astrocosmos.com/ (extensive materials compatibility table., i.e., corrosion charts)

4) There are both Teflon, quartz glass and exotic metal coated electric heaters (if your heat requirement isn’t huge). see http://www.clepco.com/plating/index.html or
http://www.process-technology.com/processtechnol/products.htm

Hope this helps,
Ken