Ask The Brewmasters

Well we were just having some welding done on our 20bbl HLT, few little repairs and upgrades after 12 years of service. One of the big ones was a new port for mounting a spray ball in there to better descale it, as it didn't come with one and our descaling efforts have been pretty hit and miss over the years. Ran it for a couple hours and it was much, much, much better in there. Sweet! Then the leaking began. 

On further inspection, there were several dozen tiny little stress cracks around the bottom edges of the tank. Presumably stress corrosion cracking where it's most shouldering the load and from a decade of hot/cool/hot/cool. Our water is 18ppm chloride and 28ppm sodium, either due to how the city is treating it or saltwater intrusion into our aquifer (we are on an island after all). Presumably the scale had been plugging the cracks and cleaning opened them up. No good deed goes unpunished I guess. 

Welders did what they could but I suspect we'll be in whack-a-mole mode from here on out. Any advice on limiting the creeping damage? I read the Stainless Steel in the Brewery article from Volume 38, Number 2 • 2001 • Pages 67-82 which was helpful but also...I'm a tired brewer not a metalurgist. 

Got me thinking about my boat... Any reason not to stick a sacrificial anode in there? (Aluminum-zinc presumably.) I know that's primarily for galvanic corrosion, but wondering if it would help? If the cracking is from physical stress no, but I gather the cracks often start at sites where pitting or some other corrosion has occurred. Anyhow, any practical advice would be appreciated. Thanks!

This is not an uncommon issue. The combination of temperature and chlorides is the root cause, so I don't think a sacrificial anode will work. Chlorides react with chromium destroying the protective passivation layer.   I would normally recommend 316L stainless for HLTs, especially if the local water has a chloride content. From my perspective (and experience) the tank is toast. Your comment on "whack-a-mole mode" is correct. 

Well we were just having some welding done on our 20bbl HLT, few little repairs and upgrades after 12 years of service. One of the big ones was a new port for mounting a spray ball in there to better descale it, as it didn't come with one and our descaling efforts have been pretty hit and miss over the years. Ran it for a couple hours and it was much, much, much better in there. Sweet! Then the leaking began. 

On further inspection, there were several dozen tiny little stress cracks around the bottom edges of the tank. Presumably stress corrosion cracking where it's most shouldering the load and from a decade of hot/cool/hot/cool. Our water is 18ppm chloride and 28ppm sodium, either due to how the city is treating it or saltwater intrusion into our aquifer (we are on an island after all). Presumably the scale had been plugging the cracks and cleaning opened them up. No good deed goes unpunished I guess. 

Welders did what they could but I suspect we'll be in whack-a-mole mode from here on out. Any advice on limiting the creeping damage? I read the Stainless Steel in the Brewery article from Volume 38, Number 2 • 2001 • Pages 67-82 which was helpful but also...I'm a tired brewer not a metalurgist. 

Got me thinking about my boat... Any reason not to stick a sacrificial anode in there? (Aluminum-zinc presumably.) I know that's primarily for galvanic corrosion, but wondering if it would help? If the cracking is from physical stress no, but I gather the cracks often start at sites where pitting or some other corrosion has occurred. Anyhow, any practical advice would be appreciated. Thanks!

This is not an uncommon issue. The combination of temperature and chlorides is the root cause, so I don't think a sacrificial anode will work. Chlorides react with chromium destroying the protective passivation layer.   I would normally recommend 316L stainless for HLTs, especially if the local water has a chloride content. From my perspective (and experience) the tank is toast. Your comment on "whack-a-mole mode" is correct. 

Well we were just having some welding done on our 20bbl HLT, few little repairs and upgrades after 12 years of service. One of the big ones was a new port for mounting a spray ball in there to better descale it, as it didn't come with one and our descaling efforts have been pretty hit and miss over the years. Ran it for a couple hours and it was much, much, much better in there. Sweet! Then the leaking began. 

On further inspection, there were several dozen tiny little stress cracks around the bottom edges of the tank. Presumably stress corrosion cracking where it's most shouldering the load and from a decade of hot/cool/hot/cool. Our water is 18ppm chloride and 28ppm sodium, either due to how the city is treating it or saltwater intrusion into our aquifer (we are on an island after all). Presumably the scale had been plugging the cracks and cleaning opened them up. No good deed goes unpunished I guess. 

Welders did what they could but I suspect we'll be in whack-a-mole mode from here on out. Any advice on limiting the creeping damage? I read the Stainless Steel in the Brewery article from Volume 38, Number 2 • 2001 • Pages 67-82 which was helpful but also...I'm a tired brewer not a metalurgist. 

Got me thinking about my boat... Any reason not to stick a sacrificial anode in there? (Aluminum-zinc presumably.) I know that's primarily for galvanic corrosion, but wondering if it would help? If the cracking is from physical stress no, but I gather the cracks often start at sites where pitting or some other corrosion has occurred. Anyhow, any practical advice would be appreciated. Thanks!

Well we were just having some welding done on our 20bbl HLT, few little repairs and upgrades after 12 years of service. One of the big ones was a new port for mounting a spray ball in there to better descale it, as it didn't come with one and our descaling efforts have been pretty hit and miss over the years. Ran it for a couple hours and it was much, much, much better in there. Sweet! Then the leaking began. 

On further inspection, there were several dozen tiny little stress cracks around the bottom edges of the tank. Presumably stress corrosion cracking where it's most shouldering the load and from a decade of hot/cool/hot/cool. Our water is 18ppm chloride and 28ppm sodium, either due to how the city is treating it or saltwater intrusion into our aquifer (we are on an island after all). Presumably the scale had been plugging the cracks and cleaning opened them up. No good deed goes unpunished I guess. 

Welders did what they could but I suspect we'll be in whack-a-mole mode from here on out. Any advice on limiting the creeping damage? I read the Stainless Steel in the Brewery article from Volume 38, Number 2 • 2001 • Pages 67-82 which was helpful but also...I'm a tired brewer not a metalurgist. 

Got me thinking about my boat... Any reason not to stick a sacrificial anode in there? (Aluminum-zinc presumably.) I know that's primarily for galvanic corrosion, but wondering if it would help? If the cracking is from physical stress no, but I gather the cracks often start at sites where pitting or some other corrosion has occurred. Anyhow, any practical advice would be appreciated. Thanks!

Yes, unfortunately I have to agree with Bradley. An anode will prevent general corrosion, but not SCC. The cracks are initiated and will keep propagating with the presence of chlorides (although I consider yours to be low) until the stress is removed. Welding them will work but will keep sensitizing the metal in the heat affected zone, making the metal more susceptible to SCC. If you can't afford to replace the tank, then another solution may be to coat the entire bottom of the tank (assuming that's were the problem is) with epoxy, thereby plugging the cracks and removing the environment.

Well we were just having some welding done on our 20bbl HLT, few little repairs and upgrades after 12 years of service. One of the big ones was a new port for mounting a spray ball in there to better descale it, as it didn't come with one and our descaling efforts have been pretty hit and miss over the years. Ran it for a couple hours and it was much, much, much better in there. Sweet! Then the leaking began. 

On further inspection, there were several dozen tiny little stress cracks around the bottom edges of the tank. Presumably stress corrosion cracking where it's most shouldering the load and from a decade of hot/cool/hot/cool. Our water is 18ppm chloride and 28ppm sodium, either due to how the city is treating it or saltwater intrusion into our aquifer (we are on an island after all). Presumably the scale had been plugging the cracks and cleaning opened them up. No good deed goes unpunished I guess. 

Welders did what they could but I suspect we'll be in whack-a-mole mode from here on out. Any advice on limiting the creeping damage? I read the Stainless Steel in the Brewery article from Volume 38, Number 2 • 2001 • Pages 67-82 which was helpful but also...I'm a tired brewer not a metalurgist. 

Got me thinking about my boat... Any reason not to stick a sacrificial anode in there? (Aluminum-zinc presumably.) I know that's primarily for galvanic corrosion, but wondering if it would help? If the cracking is from physical stress no, but I gather the cracks often start at sites where pitting or some other corrosion has occurred. Anyhow, any practical advice would be appreciated. Thanks!

Yes, unfortunately I have to agree with Bradley. An anode will prevent general corrosion, but not SCC. The cracks are initiated and will keep propagating with the presence of chlorides (although I consider yours to be low) until the stress is removed. Welding them will work but will keep sensitizing the metal in the heat affected zone, making the metal more susceptible to SCC. If you can't afford to replace the tank, then another solution may be to coat the entire bottom of the tank (assuming that's were the problem is) with epoxy, thereby plugging the cracks and removing the environment.

Well we were just having some welding done on our 20bbl HLT, few little repairs and upgrades after 12 years of service. One of the big ones was a new port for mounting a spray ball in there to better descale it, as it didn't come with one and our descaling efforts have been pretty hit and miss over the years. Ran it for a couple hours and it was much, much, much better in there. Sweet! Then the leaking began. 

On further inspection, there were several dozen tiny little stress cracks around the bottom edges of the tank. Presumably stress corrosion cracking where it's most shouldering the load and from a decade of hot/cool/hot/cool. Our water is 18ppm chloride and 28ppm sodium, either due to how the city is treating it or saltwater intrusion into our aquifer (we are on an island after all). Presumably the scale had been plugging the cracks and cleaning opened them up. No good deed goes unpunished I guess. 

Welders did what they could but I suspect we'll be in whack-a-mole mode from here on out. Any advice on limiting the creeping damage? I read the Stainless Steel in the Brewery article from Volume 38, Number 2 • 2001 • Pages 67-82 which was helpful but also...I'm a tired brewer not a metalurgist. 

Got me thinking about my boat... Any reason not to stick a sacrificial anode in there? (Aluminum-zinc presumably.) I know that's primarily for galvanic corrosion, but wondering if it would help? If the cracking is from physical stress no, but I gather the cracks often start at sites where pitting or some other corrosion has occurred. Anyhow, any practical advice would be appreciated. Thanks!