Help with cans bulging/popping with Unfiltered beer

[hokus]

We are pretty novice with packaging, currently using a mobile outfit and don't do any sort of filtering currently. We have established shelf lives (for flavor) of 3 months on most of our can products. We are starting to see some feedback of some cases that are bulging/popping/exploding out in the market. These cases are being stored warm (supposedly 70) at our wholesalers and distributors. Most cases that are in question are beyond our established shelf life, but are still being found on the shelves. My questions:

-Knowing filtering and pasteurizing would be the best thing and using finings, what would be some things to help eliminate the issue. Anything we should be looking for. All beer that is packaged was thought to be at terminal gravity.
-Is it practical to ask wholesalers to store these cans cold?
-Being that the beer is past our shelf life for flavor, do you think we should be responsible for a refund? Opinion?
-Should we be looking at possibility of contamination from the mobile outfit as a cause for re-fermentation/swelling cans?

[TonyT]

Cans don't just explode...either the beer wasn't at FG at packaging or you have a contamination problem. Have you done forced fermentation tests on the beer to determine your actual lowest possible final gravity, then compared that to your measured FG? Have you sent any finished cans off for lab analysis?

[Larry Doyle]

Sounds like you may want to start a quality control program before you go out of business.

Yes, you are responsible for your cans bulging and blowing up in the marketplace. If you want to point to the shelf life fine print be my guest but that will only hasten your demise as a business.

Yes, a dirty seamer can and will cause your product to spoil.

If you get to the point where you are actually checking the CO2 content in your cans be aware that a bulged can will give you a false low CO2 reading.

[hokus]

All the cans in question should have been at final FG, but this is something I am already looking at more on my end to improve upon.

Would a beer that isn't at FG take 5-6 months to finally show signs of bulging cans? Can it take that long, or would it happen sooner?

Our mobile guy does not provide any proof of sterile seaming, other then I can watch them CIP and spray in down before they start filling. Also they are using a simple basin of sanitizer to dip the cans in before sending them through the line, thoughts on this being a cause for concern? Maybe the cans themselves are not sterile enough? What about the can lids? On most machines I never see the lid get any sort of sanitizing prior to being placed on the can.

Recommendations on labs to send to?

Thanks

[hokus]

I also wanted to add that this seems to be an issue that is few and far between. Not every can in the cases will have the problem, and not all cases in the batch have the same problem. This tends to make me think sani issues, but I am not an expert.

[Thirsty_Monk]

Just to point out sterile and sensitize us not the same. So let's not interchange these two terms.