Advice on stainless steel as valve and seat material for bottom pour pot

[Whitesmoke]

Hi fellow casters,
Whitesmoke from Australia here. It has been a while since I was here last.
I moved this from the This Old Pot sticky-wrong place -OOOpps!

I have taken into my head to fabricate a bottom pour pot. I can see the time saving of a bottom pour pot where I can dispense with the dipper against the advantage of sliding a mold underneath and pulling a lever.The clean lead will be good as well.

I have reviewed the pearls of wisdom contained in this thread, but still seek yet more information. Information on the best material for the seat and the valve to best resist against the inevitable corrosion is what I seek.

I am hoping to use stainless steel and it looks from what I have found that 316L might be suitable for low temperatures typically found in a pure lead ball procedure though there is some corrosion at higher temperatures.

The valve seat is of concern as being that it is not readily removed ( being welded in the the pot base )

The valve face and stem is no problem, I think, and can be made of say some 1/4" or 5/16" round bar which can be made easily removable and able to be placed in my lathe chuck.

The pot itself is a cut down 4.5 kilo( 10 lbs to you blokes) LPG gas cylinder which will straddle a three ring gas burner. The pot will incorporate a shelf to hold my .535" round ball moulds.
I don't wish to cast until it gets cooler as it is 95 degrees here at the moment. When it gets cooler towards May I shall cast my years supply which is about 2000 balls.
If any one has had success with a stainless valve and seat, I would certainly appreciate hearing about it.

Any other thoughts or advice on this which you can offer particularly regarding the valve /seat alternate material shall be appreciated.

Thanks in advance

Whitesmoke

[jsizemore]

I would use a harder material as the welded in seat. The stem is easily manufactured and replaced. 10lbs is a bit on the small side for volume casting, but you can always put less in a 20-40lb pot. More lead in the pot means more pressure at the nozzle when full. If you need it.

[OldBearHair]

Just thinking, Why not weld a threaded boss at the bottom of the pot so that you could replace the seat. Never have done that myself except in other applications.

[Burnt Fingers]

I would use a harder material as the welded in seat. The stem is easily manufactured and replaced. 10lbs is a bit on the small side for volume casting, but you can always put less in a 20-40lb pot. More lead in the pot means more pressure at the nozzle when full. If you need it.

A 10LB propane tank is a pretty big tank. It's going to hold more than 10 lbs of lead.

[john.k]

Be aware that 316 on 316 is just waiting to seize without any provocation.....and working at 350C in a dry environment would be ideal for seizure......a 400 series chrome stainless might be OK for one of the components.

[jim147]

That bung idea for the seat sounds pretty good.

[Mk42gunner]

I like the replaceable bung idea for the seat, and I think I would make the needle of a totally different material just to thwart the idea of seizing. Maybe going as far as making a few from different metals.

2,000 .535" Round balls per year sounds like a lot to me, good luck.

Robert

[quack1]

I use a home made natural gas fired pot. The first bit of advice I'd offer is to make the whole pot out of stainless if possible. Anything made of steel will rust, and the heating cycles will just make the rusting worse. I did make the valve and seat from stainless, no idea of what type of stainless. I just used what I had in the scrap pile. After about 40 years of use, they are still working as new, no sticking or galling. I made the actual seating area fairly small, figuring the smaller the area where the two pieces touch would cause the seal to be better. After I machined the valve and seat, I lapped the seal with 400 grit valve compound. The seal was good enough to hold water in the pot without leaking. I only ever get an occasional lead drip when casting. Something you'll need to do when melting a large amount of lead is to weight the arm the valve is attached to. The more lead in the pot, the more the valve will want to float away from the seat. When I first used the pot I couldn't figure out why i was having so much lead leakage. A big weight on the end of the lever took care of the problem. Also, consider fabricating an adjustable limit for handle movement. Very handy to be able control the flow of lead going into the mold. Think of the difference in volume needed to fill a 500gr 45 caliber bullet vs a 40gr 22 caliber bullet.
Here's a few pictures of the valve and seat. Hope this helps.
https://i.imgur.com/ztXADAal.jpg
https://i.imgur.com/XovwV1Fl.jpg
https://i.imgur.com/zL7wPSGl.jpg

[Scrounge]

Just thinking, Why not weld a threaded boss at the bottom of the pot so that you could replace the seat. Never have done that myself except in other applications.

What he said. You could either make your own from stainless, or whatever, or buy a "Bulkhead" fitting in stainless or whatever. Something like this: https://www.amazon.com/Bulkhead-Connector-Stainless-Thru-Bulk-Fitting/dp/B08BHYM5PS I know you're WAY down south, so you might not be able to get this exact item, but it will give you the idea, at least. If you dimple the bottom off your pot enough, you could sink the whole fitting below the inner surface of the pot so you can scrape it without hanging up on the fitting.

Bill

[GregLaROCHE]

From what I’ve seen on this forum, many people lap the valve in place. In fact I’m getting ready to do it to mine. It seems it would be a lot easier if you just lapped it in place, if it works. In that case, maybe a softer, rather than harder metal would be better.

[OldBearHair]

Stainless valve / brass seat made from a commercial brass fitting screwed into the welded stainless boss ??? To the dimensions of Quack 1's model.

[3006guns]

Stainless valve / brass seat made from a commercial brass fitting screwed into the welded stainless boss ??? To the dimensions of Quack 1's model.

Isn't there the danger of the lead "soldering" itself to the brass? I know.......brass molds never have problems, but the environment is a bit different inside a pot.

[OldBearHair]

tE[QUOTE=3006guns;5172553]Isn't there the danger of the lead "soldering" itself to the brass? I know.......brass molds never have problems, but the environment is a bit different inside a pot.[/QUOTE
Kindly submitted:
Should a problem arise just unscrew the fitting and replace it. Another idea is to use powdered glass to the parts of the brass in contact with the lead. It would make a great surface to receive the stainless valve lapped in with fine grit silicone carbide. ( rubbing compound ). Fire a half dozen fittings at a time with the glass for spares for replacements....... if that is necessary.

[Whitesmoke]

After seeing quak1's pot I am so impressed I have come up with a new pot.

Thank you quack1.
My wife volunteers at a church run thrift shop and spotted the stainless pot.

I scored a stainless steel pot maybe 8 3/8" diameter by 4" deep with a flat bottom .The wall thickness is quite good maybe 3/32 with a 1/4" thick base that I can probably drill and tap,no welding?

Its scratched and old, but for $3 it was mine. The LPG cylinder was going to be a pain in the bum in making the valve rod close to the cylinder side because the base curvature

I am enthusiastic about the brass seat protected by glass but not too sure on how the powdered glass is applied.

I take it that the brass is taken to a red heat under flame and the valve surface is dipped into the powdered glass. Or is it a kiln process where the powdered glass is sprinkled on the hot brass? Can you please enlighten me?

I own an electric furnace so this process may be possible.

Thanks
Whitesmoke

281660

[OldBearHair]

First thing is to refer to Quack 1's post #8 about using scrap stainless steel to make the valve and seat that has lasted 40 years.

I am enthusiastic about the brass seat protected by glass but not too sure on how the powdered glass is applied.

Quote:
I take it that the brass is taken to a red heat under flame and the valve surface is dipped into the powdered glass. Or is it a kiln process where the powdered glass is sprinkled on the hot brass? Can you please enlighten me? I own an electric furnace so this process may be possible. End quote. I like both of your suggestions. If I remember correctly, Use borax as a flux. Better yet is to google copper enameling. Check Rio Grande Supply Albuquerque NM for books etc.

[bangerjim]

Just stick with SST for the seat and forget about brass and glass coatings. Too much hassle.

If you are worried about the valve seat, do as above and weld a threaded boss in and screw the seat in and out if needed.

If you are attempting this little project, you must have access to a machine shop and a lathe???????????????

[44magLeo]

I haven't looked at many brands of pots. I have owned Lee pots for years.
Lee uses spouts that mount through a hole in the bottom of the pot. The spout is kinda top hat shaped. Just below the breim of the top hat it's threaded. For abouit 3/8" then is smooth. A nut threads onto the threads.
A hole in the bottom of the pot lets the body of the top hat slips through the hole. The brim of the top hat prevents the spout go through. The nut threads onto the Spout to hold it in place. The tension of the nut seals the spout to the pot.
As I said I haven't seen just how other pot are made, so I can't say yea or nay on how they mount the spout.
I thought that when I build a larger capacity pot than My Lee 4-20 I would use a 1/2" stainless steel bolt about 1/2' or 3/4 ' long. Drill a 1/8' holw all the way through. From the head end drill a 1/4 or 3/8" hole about 1/2 way through the bolt.
Grind the head of the bolt down so it's not so thick and rounded a bit. Leave enough so it's strong enough to be snugged down when mounted so it won't leak.
Then use sai a 1/4' steel rod with a tapered end to fit the spout. I would make the handle to lift the rod long and bent down the side of the pot with a heavy knob like RCBS and Lyman use. The weight of this long handle and heavy knob will help seal the valve.
I also thought about using a spring in the handle mount to help seal the valve too.
Making the handle mount adjustable for flow control is a must.
I thought I might make this pot with a 50 or so pound caopacity. Giving me enough room for mixing larger batches of specific alloys.
I'll use my propane fired big pot for melting down large batches of lead pipe or WW's and such and pouring them into ingots.
When I want to mix a batch of a certain alloy I can use this 50 lb. pot I could also this large pot for casting a larger quanity of boolits of a specific alloy.
I have the design of the pot pretty much worked out. The heating I'm still working on. I would like it to be electric for easy temp control. A 240 volt element and a PID will do quite well. Gas fired is easily controlled but more costly to do automatically.
Leo

[Mal Paso]

I would not worry about corrosion, lead oxides and crud build up causes drips. I would steal the Old Pro Melt valve style which uses a flat ended valve pin with a slight radius in a tapered hole deep enough that the pin can never come out. Minimum contact area gives a better seal. Something like this.

There are some cheap HSS taper reamers that would cut mild steel OK.

[JLF]

If you weld on the bottom of the pot a tube with a male thread, into which you can screw a gas stopcock, they are made of bronze. Said valves work with a conical socket. Which will allow you to manage the outlet flow of the foundry.
This is an approximate scheme

https://i.postimg.cc/Ln07sDX3/LLP-gas.jpg (https://postimg.cc/Ln07sDX3)
On the other hand, if you use a stainless steel seat, due to the difference in electronegativity between the iron in the pot and the base, it will accelerate the oxidation in the base near the seat ...