try these:

Ductile Iron Pipe Research Association
http://www.dipra.org

Ductile Iron Society
http://www.ductile.org

There are also some out of print books on the subject put out by either mmanufacturers or trade organizations.  You might check with a used book store that handles technical subjects.

Where is the pipe?  Is it coated or bare?  How old?  Why are you interested in protecting it?

Email: Hscribner@henkelsandmccoy.com

I would be leary of relying on DIPRA for ductile iron corrosion info. This organization is funded by DI manufacturers and their job is convince engineers to select DI. I have seen plenty of DI corrosion failures in the field on pipe less than 20 years old, even with the polyethylene wrap. You might want to try nace.org, the corrosion engineering organization, but the DI people have managed to stiffle good guidance. They also often cite studies that incorporate data for grey cast iron, which experiences significantly different corrosion processes.

If any one can tell me about relation of half cell corrosion to the actual corrosion of steel in concrete.I want it for my master's thesis.