Metal waste tanks?

[Dave Park]

Hi.

I have in the past made custom metal tanks for different uses, like fuel/coolant in antique aircraft, or fresh water tanks, without problems.

Are there any special considerations with gray and black waste tanks that would limit metal choices due to corrosion, wear, fatigue or etc?

I ask, because I could fabricate custom tanks in metal more comfortably and easily than in plastics or fiberglass. I can also do things like make a sealed inner tank, then an outer tank with a 1" insulated space, so tanks don't freeze in winter, and also, the tanks would be perfect fits for my projects.

What do you think? What am I missing?

[Dave Park]

Anyone? Bueller? Bueller?

I'll even take opinion over certainty!

[Minno]

Wouldn't metal tanks corrode in a few years? Esp. black water with chemicals we use?

Kay

[Dave Park]

I can line metal tanks with plastic coatings, so no metal/black water contact is possible.

[Ganaraska]

They used to use tanks made of galvanized sheet metal at least for fresh water, they switched to plastic because they are easier and cheaper to make.

Corrosion and freezing are the 2 big problems. If you have the corrosion problem beat with a lining then all you have to worry about is freezing.

Make the sides taper like a funnel or inverted pyramid. That way if they freeze the water climbs the sides and does not do any damage. Insulation will help but will only stave off freezing for a few hours. You need to assume they will freeze solid at some time.

[tvanwave]

Originally Posted by Dave Park

Hi.

I have in the past made custom metal tanks for different uses, like fuel/coolant in antique aircraft, or fresh water tanks, without problems.

Are there any special considerations with gray and black waste tanks that would limit metal choices due to corrosion, wear, fatigue or etc?

I ask, because I could fabricate custom tanks in metal more comfortably and easily than in plastics or fiberglass. I can also do things like make a sealed inner tank, then an outer tank with a 1" insulated space, so tanks don't freeze in winter, and also, the tanks would be perfect fits for my projects.

What do you think? What am I missing?

Drain, fill openings would have to conform to industry sizes. Stainless steel would be pretty much corrosion proof for a looong time.

[Aerowood]

I think Stainless steel would be the ideal choice.

[mbrod666]

I personally like epoxy lined mild steel for a number of reasons including ease of fabrication and flexibility. Stainless has issues with being brittle and stress corrosion cracking caused by exposure to acid and some chemicals. That's why most stainless steel transports have interior linings.

[thecatsandi]

Originally Posted by Dave Park

Hi.

I have in the past made custom metal tanks for different uses, like fuel/coolant in antique aircraft, or fresh water tanks, without problems.

Are there any special considerations with gray and black waste tanks that would limit metal choices due to corrosion, wear, fatigue or etc?

I ask, because I could fabricate custom tanks in metal more comfortably and easily than in plastics or fiberglass. I can also do things like make a sealed inner tank, then an outer tank with a 1" insulated space, so tanks don't freeze in winter, and also, the tanks would be perfect fits for my projects.

What do you think? What am I missing?

The tanks would have to Stainless Steel. Bodily output is corrosive as well as some of the chemicals used to keep the smell down.
The tank would have to be well supported.

[duggie]

What would you line the interior of the stainless tank with?

[masseyfarm]

I don't think you can beat the "plastic tank" for weight savings.

Dave

[perryg114]

Stainless steel would work but you need to know what you are doing with welds. Welds are where you’re going to have the most problems because you don't know what the properties are going to be once something is melted and stuff segregates. I would tend toward plastic holding tanks and if you must then make a stainless steel fresh water tank. Stainless does not like chlorine so you have to be careful on when you sterilize tanks not to overdo it. You want 300 series stainless steel.

Perry

[SmokelessJoe]

Does anyone have an opinion or knowledge to offer on using 5052 aluminum ( its supposed to resist corrosion some) for a FRESH WATER tank?

Thanks,


Sergei

[perryg114]

Anodizing would be best but it needs to be done after fabrication. It might be ok without it. Aluminum is used in cooling systems with anticorrosion additives and you don't want that in your drinking water. For long term storage I am worried a little. Typically it is used for things like diesel fuel that is relatively non-corrosive.

Perry

[SmokelessJoe]

I should also clarify that the FRESH in my case is never used for driinking, only washing.


Sergei

[Kevin245]

Originally Posted by duggie

What would you line the interior of the stainless tank with?

I would not line the interior of a stainless tank.

[Foiled Again]

Originally Posted by masseyfarm

I don't think you can beat the "plastic tank" for weight savings.

Dave

Agree heartily. Also there are several suppliers with reasonable prices.

Paula

[SmokelessJoe]

Using plastic is only viable if you can use a stock size, tons of which are available.

Dave Park, who originated the question is a skilled builder so he must have in mind a special size.

Metal is the only reasonable way in that case. A plastic blow molded tank would require paying for a mold and if you need to bend sheet goods you need an giant oven so special size plastic will be cost prohibitive.


Sergei