Surprise Sanke Pressurization

[Positronic_Matrix]

I brewed a (stubborn) pale ale in Jan 2020 (referenced in this thread). I left the beer to ferment for several months due to work travel, finally transferring the beer from a conical to a Sanke keg at the end of Apr 2002. With the distractions of COVID-19, the beer remained in a keg in my washroom (room temperature) until 13 Jun 2002. That’s 4 months of fermenting and 1.5 months in a Sanke keg. When I went to force carbonate the keg today, upon connection of the D-coupler, the emergency pressure release valve immediately activated. At first I thought it was a D-coupler valve failure, however after switching the coupler out with a new one, I realised that the keg was at an extreme pressure, likely 45-60 PSI. I spent an hour slowly bleeding the keg down and it’s now in my keezer at a nominal pressure cooling down.

I assumed that fermentation was done after 4 months and was surprised by the pressure, which I assume is from continued fermentation. I’ve sampled the beer multiple times as it is cooling in my keezer and it’s a middle-of-the-road IPA, drinkable but not exceptionally good or bad, so no strange infection seems to be present. The questions I have are as follows:

1. Could I have caused property damage or personal injury from an overpressurized Sanke keg?
2. Is it possible that this beer went through a second round of fermentation after being transferred from the conical after 4 months?
3. What tools exist to prevent dangerous build up of pressure in Sanke kegs after transferring beer?

Any insight or advice would be appreciated. I’ve seen everything in brewing, so this new unexpected outcome is a welcome surprise, even though it could have blown up my washroom.

 

[Vale71]

Could I have caused property damage or personal injury from an overpressurized Sanke keg?

AFAIK Sanke kegs don't have a PRV so it's possible to exceed their maximum rated pressure and have them blow up.

Is it possible that this beer went through a second round of fermentation after being transferred from the conical after 4 months?

Absolutely. There's plenty of complex sugars in finished beer that can be further fermented but first you have to get an infection.

What tools exist to prevent dangerous build up of pressure in Sanke kegs after transferring beer?

I'm not aware of any. Of course commercial beer is usually pasteurized so it's supposed to be quite stable so that is not really an issue in that case.
EDIT: it appears newer kegs can be outfitted with a burst-disc type PRV to prevent accidents. I'm not aware of older kegs being able to be retrofitted though.

 

[Dave Sarber]

PRV, or pressure relief valve.
I don't know what it would take to actually blow a sanke keg, but I'm pretty sure you weren't even close.

 

[Positronic_Matrix]

I went back to my brew notes and realised that this particular batch was stuck for several weeks. To restart the process, and to experiment with something new, I added Beano. I strongly suspect that over several months In the keg, the conversion of complex to simple sugars continued, resulting in continued fermentation. I did not realise the process was so slow and long.

I now have a new rule of thumb: do not mix Beano and kegs (even after several months) unless a pressure relief valve is used.

 

[verboten]

I use glucoamylase and keg every beer I make. You just have to wait until it’s finished before packaging,

 

[day_trippr]

I use glucoamylase and keg every beer I make. You just have to wait until it’s finished before packaging,

Well, yeah, once you've gone that route you're definitely waiting on stable gravity checks.
But, why are you using enzymes on "every beer you make"? Uber dry beer fan?

Cheers!

 

[verboten]

Well, yeah, once you've gone that route you're definitely waiting on stable gravity checks.
But, why are you using enzymes on "every beer you make"? Uber dry beer fan?

Cheers!

This was in reference to the beano comment just above mine.
I should have phrased it as When I use glucoamylase....verify stable, and I Keg every beer I make."

I do not dry out every beer, but i do a few. Yes, I like the nice dry beer at about 5% Cheers!

 

[Dr_Jeff]

You could build a spunding valve for a sanke coupler.
Take a nickel and put it on the top of a coupler, between the beer nut and the seal to close off the beer out connection.
Take the check valve out of the gas side, attach the spunding valve there.