Leaky Custom Weldless Bulkhead

[adempewolff]

Hello all,

I'm an expat in China and currently assembling equipment to brew 60L (~15 gallon) batches--20L batches just were not meeting the demand from the other expats in my city. The nice thing about living in China is it's really easy and affordable to order exactly the equipment you need. The bad part is that there isn't a big community here to help you troubleshoot exactly what you need. Here is my problem:

I have an 80L insulated stainless steel tea/soup container (really popular in Asia, work perfect for brewing!) that I'm using for my ML tun, and a similarly sized stainless steel brew kettle. both have two NPT 15 (outer diameter ~20mm) weldless bulkhead fittings installed (one for ball valve, one for a thermometer). You can't really find suitable stainless steel bulkhead fittings here, so I just ordered some parts from a factory that does custom 304 stainless fittings. The fittings are essentially a nipple with hex nut extenders on each end, stainless steel washers for spacing and an o-ring on the inside between the washer and a wall.

I had thought that since the main problem facing people in getting leakless bulkheads was the o-ring over the thread that I would be problem-free using a nipple and spacers to get the o-ring off the thread. However, when I installed them everything was incredibly leaky.

So, I saw two options: 1) get some sort of washer/nut to constrain the o-ring from expanding outwards, forcing it to expand inwards and form a seal and 2)weld my hex-nut to a washer so I just needed a seal between the wall and the washer. I went for the second option as it was easier for me to get them welded than order new custom parts.

With the welded nuts/washers, there is a much better seal--especially on the ML tun--but everything is still a little leaky when full of water. I can't for the life of me figure out what the problem is, or even whether the water is leaking past the O-ring or the threads between the nipple and nut (which are tight and have plenty of teflon tape on them).

I'm wondering if getting a silicon washer rather than o-ring might solve my problem?

Any suggestions or insights to what might be causing the leak would be appreciated! Thanks in advance!

Following are pictures of my set up.

ML-tun, interior:

ML-tun, exterior:

Close-up of ball-valve fitting on ML-tun (there is length of PVC piping sheathing the nipple and transferring the weight from the outer washers to the interior wall):

Brew kettle, interior:

Brew kettle, exterior:

Welded washers/nuts:

 

[alexnharvey]

A silicone washer might well work better. The nut I used (for my heating element) came with a groove that traps the o-ring and compresses it. http://www.bargainfittings.com/index.php?route=product/product&path=36_38&product_id=57

 

[HDIr0n]

what kind of material is your current o-ring?

 

[KegWrangler]

Is there teflon tape on the threads between the nipple and your welded washer-nuts? (By the way very cool idea on those!) If not the liquid could be wiggling out between those threads.

A silicon washer/gasket (flat versus round cross-section) might work a little better. What ever you try should be as thick as possible since your mashing it up against a curved surface.

 

[adempewolff]

Thanks to all for the replies!

@alexnharvey: I ordered a bunch of silicon washers to see if they'll work better. My back up plan is to order some more custom nuts with a depression machined in for the o-ring, but I'm not sure exactly how big to make it/how to shape it. I guess I could use the image from the link you sent me as a guide.

@HDIr0n: They are all silicon.

@Keg wrangler: Yes, I did put teflon tape on those threads. In fact, there is teflon tape on all the threads in those pictures (with the exception of the ball valve/barb connection). I'd like to claim credit for the washer/nut idea, but I saw it in a forum post somewhere else (can't find the link). What might be the problem is, while the outside weld is pretty neat, the welder was a little messy on the inside and melted off a bit of a couple of the outmost threads on few of the nuts. I'm hoping that that isn't the problem though, the leak would have to get past the first 20 good threads before reaching the damaged ones...

The curved surface is also probably a big player. The washers I ordered are pretty thick so hopefully they'll do the job. I suppose I could also have some curved washers made that would follow the curve of the wall but that would be more time and money--I'm keeping my fingers crossed that I can just fix this with the silicon washers...

 

[HDIr0n]

I think with some thick flat washers you should be good to go. Keep us updated as you get them in. Soo a dumb question is the shipping as stupid as it is going from the US to China as it is going from China to the US?

 

[adempewolff]

@HDIr0n It depends on how you have it shipped (Air, Sea, Chinese carrier, Western carrier, etc.) I am hoping to get some space in a shipping container to ship my equipment home when I finally move back as I can't imagine downgrading to a rubbermaid now.

I think there are certain (small) things (temperature controllers, custom fittings, etc.) that if a couple people got together it would be affordable to send even by air compared with the price in the US. For example, the "ebay" temperature controller that people buy for about $30 in the states I buy for about $13 here.

Also, if any vendors are interested in making an order of these insulated stainless ML tuns I could look around and hook them up with a supplier here. They really work perfect for brewing: easy to clean, no leaching of chemicals, and they hold temperature perfectly for well over an hour. A decent size (30L) for 5 gallon batches costs less than $25 retail, you could probably get them for less than $15 bulk, install a ball valve and thermometer (in fact I could probably even find a supplier that would do the welding as well) and still sell it for a price that homebrewers would earn back when they don't have to replace aging rubbermaids every couple years.