[MDixon]

I once researched it long ago (2001) and came up with a 10 min contact time with 200ppm bleach (FWIW - 1/2 tbsp should be 100 ppm).

I checked Palmer and he does suggest 20min, so I decided to do a little research and came up with a link on food surfaces from Auburn. The USDA suggests no less than 50ppm and no more than 200ppm. Water should be 105-120F and remain in contact from 1-5 minutes and anything less than 200ppm is supposedly a no rinse concentration, but we all pretty much know the bleach smell is a no no. Further it says, "However, chlorine sanitizers can corrode equipment and should not be in contact with stainless steel surfaces for more than 30 minutes."
http://www.ag.auburn.edu/poul/virtuallibrary/mckeeeffectivechlorine.html

So my answer of 100ppm and a few minutes was initially wrong, but now is miraculously validated  

More miraculous validation, if anyone still cares...
http://nrckids.org/CFOC/PDFVersion/Appendix%20I.pdf
http://www.factsaboutbleach.com/bleach_public_health.html
http://www.charmeck.org/Departments/Health+Department/Environmental+Health/Educational+Info/Brochures/chlorinesanitizer.htm

[zorch]

It's been several kegs, which also contributes to my overall confusion: How does an infection go from one keg to another?

You may need to replace your _gas_ lines.    I had a similar situation about a year ago... 3 kegs in a row went sour.    Eventually I tracked it down to my (opaque) CO2 line.  Apparently I had neglected to vent a pressurized keg before hooking up the gas, and it shot a bit of beer into the tubing.     I replaced the gas line (with clear tubing) and haven't had a problem since.

[Matt B]

Good point. I just noticed that some (thankfully non-infected beer) beer had managed to back flow into my co2 tank while I was force carbonating through the bev out line. I'll likely just toss all of my tubing, put the co2 tank upside down, purge the beer out, and the next time the tank has been emptied stuff it in the oven with the valve open and heating it up to ~200F for a short while to kill any possible infection in there, and then clean out the regulator as best I can with starsan and what not.

[wilypig]

I have a manifold with 6 gas lines and all my lines are now protected by check valves since I back flushed the system with a naturally fermented cider. McMaster Carr has them for about 6 bucks a piece. Well worth the cost to save a batch or 2. This can also prevent the cross flavor contamination that some people experience when feeding more than one keg from a single regulator.

[micsager]

I was curious as to how everyone sterilizes their kegs. Seems straight forward, but apparently not so for me.

I've had this perpetual problem where some of my beers are being slightly infected with what I think is lacto. I've determined that it's likely the kegs because I just tried some from the keg, has that sour twang to it, and the bottles (that I was saving for competitions now that I'm actually starting to do that) didn't. You're probably asking if I tasted it when I bottled/kegged it as well as take the FG: yeah, I did. I just don't remember tasting the twang, though I've discovered I have a hard time picking it up in a non-carbonated and warm beer, as I've kegged beer that was clearly infected and didn't really notice it at kegging time, so who knows.

I store my kegs filled with water with a couple cap fulls of iodaphore, clearly this doesn't seem to be enough. Every keg that I go through now I'm washing with PBW, boiling the posts, and running a torch along the dip tube to make sure anything that's in there is DEAD. Then running a gallon or so of star san through it, and storing it with the star-san and giving it a shake every couple of days. I haven't kegged anything since I started this regimen, I'm hoping it'll be enough .. this is miffing me off, I'm likely going to pour out 10g of american amber that actually came out reasonably good, and I just finished a pale ale that had a similar problem and just wasn't that enjoyable, I just had a hard time dumping it. I'm now past that point.

Not to be picky, but we sanitize kegs.  We do not sterilize them.