Tank modification

[distancerunner]

Has anyone bored a hole in a stainless steel tank to accommodate a larger valve?

If so, what advice can you give concerning this kind of work?

 

[Ohio Bob]

For any metal work... sharpest possible tool. Don’t skimp on quality here.

 

[ChuckD]

Slow! For metal your drill rpm’s need to be much slower than drilling wood. A cutting fluid can also help but probably not necessary for thin metal.

 

[Chuck E]

Use a hole saw for bigger diameter holes. The good ones have a pilot drill in the center.

 

[distancerunner]

Thanks for the tips.

The idea is to create a connection for 1 1/2" triclamp outlet. Should this be welded or is there a fixture that can be inserted and fastened with nuts and gaskets?

 

[Jim Welch]

I've done a lot of metalworking in my life including stainless steel. What is the wall thickness and diameter of the hole you need? Are you enlarging a smaller hole?
A hole saw or chassis punch is the best way depending on thickness of material and diameter of hole.
If a drill bit must be used make sure it is sharp, and use good cutting oil. Stainless quickly work hardens, so I've found the best way is to have the piece to be drilled well clamped and use a relatively low speed/high feed drill technique while keeping the drill bit saturated with cutting oil. By low speed/high feed means a relatively slow but not too slow) drill bit rotational speed and a basically pushing through the piece quickly.
Depending on what I was fabricating I've had to drill dozens of holes in anything from 20 ga up to 1/4" 304, 308, and 316 stainless. Whenever I could I'd use a drill press but I could easily make hundreds

 

[distancerunner]

Fixture size is likely near 1.984". Have to go to the tank to measure gauge size.

 

[Jim Welch]

Will this be a welded fitting or threaded? If welded, do you need a sanitary weld? I'm presuming yes.
That's pretty close to 2", a 2" radio chassis punch will give you a nice clean, round 2" hole with about 0.008" clearance which is a nice fit I believe for either type of fitting.
A hole saw will be far cheaper but the hole may not be as clean and perfectly round but should be good enough provided one keeps control of the drill and avoids chatter since it seems like you are looking at using a hand drill.

Edit: Also with a hole saw you will be looking at cleaning the hole after drilling with round files and emery cloth

 

[distancerunner]

A friend has a punch set.

That means finding someone who can weld stainless.

 

[CDrew]

You'll need to find a good TIG welder that does food grade (sanitary) work. That thin metal is kind of a special task. I'd let them decide how to punch the hole but I'm sure a hole saw will not be the answer as they are imprecise and leave ragged edges.

Sanitary fittings are a game changer. Sounds like a good project.

 

[vinny]

Honestly, for what it is worth it might be worth letting the welder put the hole in as well, although a friend with a punch set is a good thing. I would stop in at a welding shop with pictures and get a price. They'll tell you if it's worth punching your own hole.

I had a some brazing done on one of my set ups for the small price of a bottle of what I produced. It cost me about 8 bucks.

 

[distancerunner]

Are there bolt on fixtures that allow for skipping the welding? Would the part sticking into the tank pose a problem with filling and racking?

 

[vinny]

For what it is worth, If it is easy enough to get the tank to a welder, or if you have a friend that could come to you that is even better, but the welded guaranteed no leak part would be worth the extra effort and money to me.

https://www.hobbyhomebrew.com/produ...eel-tri-clover-threaded-clamp-nut-and-o-ring/

 

[distancerunner]

That just might work!

 

[Jim Welch]

A friend has a punch set.

That means finding someone who can weld stainless.

Be sure your friend's 2" punch is actually 2" in diameter. If it is an electrician's 2" knockout punch (which is made for 2" conduit) it will make a hole about 2 1/4- 2 3/8" or so.
I used italics but should have used bold type to highlight "radio punch" in my previous post. Radio punches, aka chassis punches, generally make an exact size hole for what they are named, not a nominal hole like electrician's knockout punches which are generally used for conduit connections.

 

[distancerunner]

Thank you for the clarification.

My friend is a former business partner. I know for a fact that it is an electrician's punch set. I made the purchase, he got it when we parted ways.

Does anyone know clearance tolerances for either or both welding fitment or for the screw on fixture?

 

[distancerunner]

Right before starting this thread (due to impatience, the desire to know, and the desire to do the job myself) I sent a message to Brewer's Hardware, a company recommended by CDrew. Here is the response:

Hey Frank,

There are weldless TC fittings but we currently do not sell them because they don’t work very well. The large surface area of the bulkhead can be torqued too easily and cause leaking. We recommend welding or silver soldering on a fitting.

Welding would be ideal. If you are local we should be able to do this for you.

Thanks

Curtis

/end quote

One of the 100L tanks has a very small welded valve. It does not leak. The other has a screw on valve. With a fresh gasket and careful tightening it does not leak. Otherwise, it leaks.

Looks like the search for a good welding shop is on. Thanks to all who posted on this thread!

 

[vinny]

I completely understand the want to do it yourself. It is why I make wine.

I am always discouraged at the thought of hiring someone to anything. Number 1, I usually lose out on at least one new tool, but mostly I lose the opportunity to build new skills and understanding.

Gotta weigh out the costs sometimes. A tig welder is really gonna offset the value of this project in the wrong direction.

Keeping your wine safe and hassle free is the best choice you can make. All I was envisioning was a leaky valve and no way to address it without transferring the whole batch.

 

[Jim Welch]

Not sure if its been mentioned and you may know this but make sure the weld shop is experienced in sanitary weld techniques. Not every weld shop does this kind of work.

Edit: Nor can every competent welder competently perform the required process for sanitary welds, it is a special technique in the welding world..

 

[distancerunner]

I completely understand the want to do it yourself. It is why I make wine.

I am always discouraged at the thought of hiring someone to anything. Number 1, I usually lose out on at least one new tool, but mostly I lose the opportunity to build new skills and understanding.

Gotta weigh out the costs sometimes. A tig welder is really gonna offset the value of this project in the wrong direction.

Keeping your wine safe and hassle free is the best choice you can make. All I was envisioning was a leaky valve and no way to address it without transferring the whole batch.

Having a full set of carpentry, most plumbing, drywall, masonry, and a full rollaway of luthiery tools, adding to the collection is less motivating. But I'm with you a hundred and ninety percent on building new skills and learning concepts.

Ultimately, the decision comes down to logic. Do I want to make wine? Or do I want to learn how to make sanitary welds on stainless. Both sound like a lot of study and practice but I'm further down one road than the other.

At some point you come to the realization that you don't have to do everything for yourself. Besides, putting some money back in circulation is good for the economy. To say nothing of your subcontractor's family.

Not sure if its been mentioned and you may know this but make sure the weld shop is experienced in sanitary weld techniques. Not every weld shop does this kind of work.

Edit: Nor can every competent welder competently perform the required process for sanitary welds, it is a special technique in the welding world..

It was mentioned before but it bears repeating. Welding car frames or columns to a house beam is a far cry from a stainless vessel that we expect total neutrality and leak proofing.