trapped gorilla in kettle

[THE volunteer]

so this last wednesday i walked in to brew and heard what sounded like a gorilla pounding on the inside of my kettle. it was a loud pop every 5-10 seconds and one of them was so hard it sent the lid jumping about 6 inches off the top! at first i thought maybe the flu/dampers could be the problem but after taking a close look found that they are working fine. there are no visable welding problems but im begining to think that it may be coming from a broken weld on one of the beams that connects the actual kettle to the outer jacket(just a guess). the noise is hard to pinpoint but think its coming from about head high. i know its not the bottom because i removed the door and saw that the floor of the kettle is welded to a small I beam thats also welded to to bottom of the jacket. the only thing i can think of is that somewhere, when it heats up, metal is flexing violently and the cause of this is a loose weld. im not sure what my next move is and im damn sure not looking forward to cutting into a 2 year old, 15bbl dme kettle to find it.
any help would be greatly appreciated(obviousley)

Jeffrey Helms
Oaken Barrel Brewing Company

[rafters_brewer]

I've witnessed similar noises on a regular basis but not at that magnitude. I've always chalked it up to insulation reinforcements adjusting to temperature fluctuations. I'm curious to hear any solutions....

[Michael Murphy]

Heat can cause stainless to move/expand alot, perhaps the material is thin and expanding and making the noise welded or not. if the welds were faulty then you would know it, but if its still working then its probaly a design flaw. I would contact the supplier of the kettle and ask them whats up.

[BeersmithMT]

Jeffrey,

I could be way off base here, but the description of your problem made me suspicious. I don't know whether your kettle is steam or direct-fired. If it happens to be a steam-fired kettle, condensation in your steam jacket can cause similar noises when hit with steam. A couple of times it was so strong I thought our brewhouse was preparing for liftoff! If you suspect condensation might be your problem, drain the condensation out of the jacket. If it continues to be a problem, check your steamtraps to make sure they are functioning properly.

[steveg]

Yeah, sounds to me like condensate trapped in the jacket. I've seen plenty of pipes rattle and bang when steam tries to push up through condensate.

You might have a steam trap and or condensate recovery line partially blocked.

[mr.jay]

Ditto on condensation in the jackets. Encountered the same problem about 6 months ago. Had my middle jacket condensate trap serviced along with the new boiler we needed, and the "gorilla" has since disappeared. The lid jumped like a smokestack flap on an 18 wheeler. I had my back to it (alone in the brewhouse), wasn't expecting it, and nearly pooped myself the first time it happened. P.S. I too have a DME system.

[BrewinLou]

Steam hammering

We get that as well. Our traps are only a year or so old. I check and clean them often but the hammering goes on. I think our condensate return tank is too small and or not low enough.

[Rob Creighton]

If you do use steam, does it run to other uses (hot water tank)? It is apparently now code here in Canada that you must have a high level sensor and alarm on your boiler. If it is in a high level condition, I am told you can get wicked hammering that can damage piping and jackets. If the steam goes to other uses, I would assume it would hammer there too for a reference point.

[ausbrewer1]

Usually these noises are associated with heat expansion and/or condensate issues. A couple of ideas not already mentioned would be reducing initial steam pressure or preheating the vessel with a hot water flush just prior to filling with wort.

[Oakenbrewer]

To put everyone on the right track, this particular kettle is a new design by DME. It's a direct-fired kettle with bottom and side chambers for improved efficiency. Jeff, I think what you are experiencing is just expansion/flexing of the stainless (as mentioned earlier). Although I never saw the manway lid jump, when I brewed at the Oaken Barrel I experienced those banging noises and was told they were normal - according to Kenny Sampson at DME. Especially when you're heating hot liquor.

Ken Price
former brewer, Oaken Barrel Brewing Co.
current brewer, Yazoo Brewing Co.