Repair of cracked brass
May 4, 2010 1:36 PM   Subscribe

I have a brass gas line manifold for a draft beer system that has developed a hairline crack. To fix it, I'm contemplating one of the following: (a) fill/wick with solder using a plumber's propane torch; (b) JB Weld epoxy; or (c) asking a friend to weld it (hi MrMoonPie!). Thoughts?
posted by exogenous to Grab Bag (17 answers total)
Soldering is probably the best solution. But I would use silver solder which you can get from a welding supply company. I'm not sure that regular solder will hold. Silver soldering is not hard but you'll probably something hotter an a propane torch. Either Google silver soldering for more information or ask on a machinist or metalworking forum.
posted by 14580 at 1:50 PM on May 4, 2010

Flux/Torch/Solder should do the trick just fine. That manifold looks like it's brass, with some brass filler or whatever solder, it should fill right in. If you've got resources like a torch and a friendly welder, avoid JB Weld at all costs.
posted by thebigdeadwaltz at 1:50 PM on May 4, 2010

I think soldering it is going to turn out to be tricky, even though that's probably the "right" way to do it.

I wouldn't use JB Weld, but maybe try one of the epoxies specifically designed for doing copper plumbing.
posted by ecurtz at 1:58 PM on May 4, 2010

Normally I am all about repairing versus replacing, but if the part in question is identical to the one you linked to, is it really worth it? It's a $30 part and it's under pressure. I might try some flux and (non-lead, drinking water safe) solder if you happen to have the stuff around and are desperate to keep it working until the new part comes in, but I'd also order the new part.

You might fix the existing hairline crack, but the fact that the crack is there suggests there's an underlying weakness in the part that's causing it to fail. Filling in the crack might or might not fix that weakness. You might fix it, only to find out in a week or a month or a year that the crack has gotten bigger or restarted in some other area. Unless you know why the part failed (e.g. you dropped it), I wouldn't trust it.
posted by Kadin2048 at 2:12 PM on May 4, 2010

Friend with experience/tools.
posted by fixedgear at 2:45 PM on May 4, 2010

This is an assembly made of multiple parts. Would you be able to replace just the part that's failed? If the supplier won't sell you just the individual part, maybe check McMaster-Carr (or even a well-stocked plumbing supply store if it's just one of the brass Ts that's failed)
posted by zombiedance at 2:47 PM on May 4, 2010

Echoing Kadin. $30 is for the manifold with the check valves and everything. If the check valves are still good, you can scavenge the valves and hose barbs, and get just the new body for like $15 (or, if it's a 2-way manifold, use a $7 Y adapter.
posted by qvantamon at 2:55 PM on May 4, 2010

Replace it, not repair. It's a pressurized part. The problem with a repair is that it may work today.. but will it continue working tomorrow? Next week? Fail at just the wrong time?

What you linked to is $30, I can't see any repair being cheaper than that, if you include the cost of your time to fix it, run to the hardware store etc.

Also, why did it crack? Is it under some sort of mechanical stress? Or just a badly made part? Are you bending it funny (for example?) If so, the next part (or repair) will fail at some point.
posted by defcom1 at 3:19 PM on May 4, 2010

Oh, yeah, and refilling a cylinder of gas will run you at least $10. One soldering job that starts leaking after you test it, and you'll already be out more than the part in gas.
posted by qvantamon at 3:26 PM on May 4, 2010

I don't know why it failed, so I don't want to throw another $30 plus shipping at a replacement that, for all I know, will also fail in a year or two.

Regarding going through tanks of gas, I did plenty of that before I figured out where the leak was, and have become pretty cautious. I have a twin-gauge regulator and found that if the main tank valve is closed, the high pressure gauge is a sensitive indicator for downstream loss of pressure. I will test a repair at twice working pressure before leaving my tank hooked up overnight.
posted by exogenous at 4:00 PM on May 4, 2010

BTW it's a low pressure application, less than 15 psi (1 bar).
posted by exogenous at 4:02 PM on May 4, 2010

dude, just replace it. the failure might not be catastrophic enough to poke your eye out, but do you really want beer leaking all over your fridge if the crack continues? Or worse, a C02 leak that drains your tank, leaving you unable to tap all that tasty tasty beer?

I ordered a 2 keg system from Keg Connection and a gauge wasn't working correctly, so they mailed me a new one. If your setup isn't that old, it might still be under warranty as well.

Like you said, it's not a super-high pressure application, so i can't see any reason other than manufacturing defect for cracks to form in brass. Unless you are tightening the connections with a hammer or something.

happy brewing!
posted by dubold at 5:11 PM on May 4, 2010

Where, exactly, is the crack?

Depending on where, you could solder it, but you're going to have a hard time getting the area inside the crack clean and well fluxed enough that solder will stick. Throwing the part across the room does not help - believe me, I've tried. Also, the valve packing is not going to like being at molten metal temperatures, which means you'd have to take the whole thing apart.

If it's one of those brass T's or the flange fitting, replace it. McMaster Carr wants $4.11 for the T and $13 for a 10 pack of the hose barbs. (I'm just guessing pipe and tube sizes here.) You can probably get what you need at Home Despot for about the same price as a roll of solder and a can of flux.

Either way, you'll need teflon tape when you put it back together.
posted by Kid Charlemagne at 5:31 PM on May 4, 2010

Yeah, but welding is fun! I'll play around with it, if you want. I'm fixin' to get a nicer setup, and this might just be the excuse.
posted by MrMoonPie at 5:53 PM on May 4, 2010

Lead free solder + flux would fix this easy. Depending on the nature of the crack you might want to drill each end to prevent it spreading. I can't get a feel for the size of the valve from the picture but you might need something hotter like MAPP instead of regular propane as a pound of brass is a lot to heat up.
posted by Mitheral at 6:23 PM on May 4, 2010

I've silver soldered many brass items. In addition to the solder, special flux is required. The brass has to be very hot to liquify the solder. Even with an oxy-acetylene torch it isn't easy. If the part is one of a kind, there would be no question about trying it. But a new part for $30? That's a no brainer.
posted by digsrus at 8:07 PM on May 4, 2010

I wound up getting a simple stainless T to split the gas line, though some time down the road I will look into repair of the assembly (either repairing the cracked bit or replacing it).
posted by exogenous at 12:24 PM on June 4, 2010

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