Weldless Bulkhead

Hello,

I am planning to make a weldless bulkhead for my 40qt Stainless Pot. I want to make mine a little bit differently than the usual construction, so I'd like some feedback about whether it will work.

This is for a bulkhead to attach a valve and diptube to a kettle.



Parts:
A: SS Washer, 7/8" ID x 1-3/8" OD x 0.062" Thick ... McMaster Part # 98126A748
B: Silicone O-Ring #211, 13/16" ID x 1-1/16" OD x 1/8" Wide ... McMaster Part # 9396K32
C: SS Washer, 1-1/8" ID x 1-5/8" OD x 0.090" Thick ... McMaster Part # 98126A803
D: (Same as A) SS Washer, 7/8" ID x 1-3/8" OD x 0.062" Thick
Bushing: 316SS Bushing, 1/2" NPT Reduced to 3/8" NPT ... McMaster Part # 4452K166

I'm thinking it would be possible to drill out the bushing for it to accept a 5/8", or more likely, 3/4" OD Stainless Tube to use as a diptube in the kettle. I figure it should friction fit inside and be tight enough to maintain a siphon without having to use a compression fitting. From what I can tell the inside of the 1/2" to 3/8" Bushing will have a minimum inner diameter after drilling the threads out of 0.675" (4548K381). This actually provides a larger flow diameter than if one were to use a close nipple for the bulkhead (4548K171).

Another concern of mine is whether the bushing will screw in far enough into the ball valve.

Here's my calculation:

0.53" Thread Engagement on Bushing - 0.062"x2 Washers - 0.090" Washer - 0.050" 18 Gauge Kettle Wall = 0.266" Thread available for ball valve

I'm using kal's design idea where the o-ring is compressed between two washers, with the bottom washer a larger diameter for the o-ring to sit and expand in.

Thanks in advance and I appreciate any comments and suggestions!

Cheers!

I don't understand why the o-ring isn't on the kettle wall; won't water/wort just leak out from the two washers? Why not use silicone sealing washers between the washer's and the kettle wall?

albannach said:

I don't understand why the o-ring isn't on the kettle wall; won't water/wort just leak out from the two washers? Why not use silicone sealing washers between the washer's and the kettle wall?

Click to expand...

+1, I would think you would want the o-ring between a washer and the kettle wall. ****Where it is now I can't see it being worth anything**** Never mind that, I just looked at the washer sizes and see what you are getting at, the oring will sit inside washer C, right? Still don't know if this will be any better than if it was not there. Plus removing one washer will get you another 0.062" of engament on your thread.

albannach said:

I don't understand why the o-ring isn't on the kettle wall; won't water/wort just leak out from the two washers? Why not use silicone sealing washers between the washer's and the kettle wall?

Click to expand...

The o-ring IS on the kettle wall. If you look at the dimensions, the o-ring fits inside the id of washer "C". The larger washer will keep the o-ring from deforming too much.


Bobby M has documented a very nice weldless design, put it does not terminate with a bushing on the inside as your does.

Your setup will make a more solid feel because when tightened down, it will be metal to metal and eliminate any wobble from the o-ring.

My concern is the radius of the kettle, and whether the o-ring will seal on the sides. Also, as you said, will the bushing thread in far enough to lock it all in place.

I used a similar setup to mount my heating element, but used a 2" coupling and a large bushing on the outside which eliminated the radius.

The o-ring size is the key... problem is when you tighten it down, you cannot see the o-ring to visually inspect that it makes contact.

Good luck,

Ed

Your oring should be on the wet side of the bulkhead. Move the kettle to between A and C and you should be great.

B

I presume the radius will be negligible since the o-ring is 0.139" wide, and with the 0.090" thick washer (C) it will compress 0.049", although I'm not sure. I wish I had these parts to just play with. My reasoning that the single 0.090" washer would be better than all 0.062" is that the o-ring may be too thick and become compressed too much (0.049" vs. 0.077" compression).

Why should the o-ring be on the wet side?

Ohio-Ed said:

The o-ring IS on the kettle wall. If you look at the dimensions, the o-ring fits inside the id of washer "C". The larger washer will keep the o-ring from deforming too much.

Click to expand...

Now I get it, thanks

I took Bobby M's design and modified it a bit. I couldn't get the o-rings local. I bought some high temp rubber gasket material in a sheet from Lowe's. Then I cut rubber washers slightly larger than the stainless washers. I have about 30 runs on the set up so far and no leaks at all. The best thing is that I have plenty of the rubber gasket material left for other projects. The rubber material is about 1/8 " -3/16" thick. Probably not food grade but so far I have noticed no ill effects or off tastes.

I see now that there is a flaw in that washer A and the o-ring will not seal off the thread area. This is why a locknut works, since it seals the threads also.

Anyone have ever try using a 5/8" diptube friction fit inside of a 1/2" nipple? SS compression fittings are really expensive.

I bought several weldless fittings and didn't have good luck. A few leaked, despite several efforts to correct them. As it turns out, I found weld fittings online for a good deal and it would have been less $$ and aggrevation had I gone this route at the beginning. Your mileage may vary.

The best place for the Oring would be in the clean notch between the flange and the threads on the reduction bushing. Unless you really mash the oring, distorting it enough to fill the threads, capillary action will win, and you'll have a leak.

if the oring/gasket goes on the flat part of the bushing, there's a flat surface for the oring to seal against. You could even put a thin washer to widen the contact area. Kinda like a real bulkhead fitting.

Pickles had some great 1/2" full thread BH's for sale in the Classified.

For your other problem with the dip tube, you could drill out a plug and silver-solder the tube in the hole. Ghetto 1/2" to tube fitting. It's actually what I plan on doing.

B