Welding Tips and Tricks

Hi everybody!

I do welding as a hobby and a friend of mine asked me to make a 12 gallon aluminum water tank for him.
He is going to put it up on his camper and use it for showering.

The main question I have is do I need to purge the tank while welding?
And would you weld brackets inside of the tank for structural strength?
The tank is about 4x20x40 inches.

Any advice would be greatly appreciated!
Cheers!

No need to purge aluminum but it wouldn't hurt if you did it anyway. You never said what thickness your metal was so there is no way to comment on structural brackets.Your shower tank project would be strong enough with 1/8" plate...no pressure only a holding tank and not a lot of water. Cut your pieces so they touch inside the corner and OS corner everything and it should be fine. Paint it black too.

The thickness would indeed be 1/8".
What do you mean by OS corner everything? (I'm fairly new to welding terminology and google gave me nothing)

My client intends to paint the water tank black for the sun to heat it's contents more effectively.
I'm not sure if that's the way it works though.
Aluminum being a fairly good heat sink, wouldn't it cool the water more than heat it?

Thanks exnailpounder!

NilsB wrote: Aluminum being a fairly good heat sink, wouldn't it cool the water more than heat it?

The fact the aluminum is such a good conductor of heat works both ways. If the outside of the tank is warmer than the water inside (from the sun hitting it, warm air temps, etc) then the aluminum will efficiently conduct the heat from the outside into the water. If the water is warmer that the air outside of the tank, it will just as efficiently carry the heat from the water out to the surrounding air.

NilsB wrote:The thickness would indeed be 1/8".
What do you mean by OS corner everything? (I'm fairly new to welding terminology and google gave me nothing)

My client intends to paint the water tank black for the sun to heat it's contents more effectively.
I'm not sure if that's the way it works though.
Aluminum being a fairly good heat sink, wouldn't it cool the water more than heat it?

Thanks exnailpounder!

OS cornering(outside cornering) means cutting your pieces to they are just short enough that the edges touch on the inside edges,(your pieces are cut short the thickness of your material x2) leaving you a 90 degree gap to weld. OS corners are really easy in aluminum and you don't need a ton of filler and they look really nice when properly done. Black paint will heat water so well because it absorbs infra-red radiation and the underlying aluminum gives it up to the water. I built a pool heater for a friend years ago that was copper pipe painted black that the water circulated through. It worked too well and the pool got too hot....the opposite was true if my buddy got drunk and left the pool pump on all night,,,the pool would lose 10 degrees at night. You get the picture.

clavius wrote: The fact the aluminum is such a good conductor of heat works both ways. If the outside of the tank is warmer than the water inside (from the sun hitting it, warm air temps, etc) then the aluminum will efficiently conduct the heat from the outside into the water. If the water is warmer that the air outside of the tank, it will just as efficiently carry the heat from the water out to the surrounding air.

Makes sense! Thanks a bunch

exnailpounder wrote: OS cornering

Do you mean something like this?

you got it!
there is a video jody has with Crummy doing just that.
craig

Yessir. Edges are pretty easy to weld that way even on aluminum. I know most people do their corners that way but I have seen guys just overlap and flat weld over the cracks and it looks like "Fido's Butt" Good luck on your project and post up some pictures if you can. Us old timers like me and motox up there^^^^ don't have lives and we depend on weld porn

manuel pulse,smooth rhythm, good prop.
craig

Side-track... Do make sure that the tank has some facility on it for straps or loops to fixate it onto/under the camper.

10+ gallons of water sloshing about in a container can tranfer quite some momentum to the sides and 'push' it around unless it's strapped down tight.

Some sort of brackets welded to the tank with bolt holes can be done too, but these do need sufficient suface to attach to the tank as this will be stress points where the forces will try to bend/tear the tank wall.

Bye, Arno.