On Sun, 30 Mar 2008 12:09:59 -0400, WaIIy wrote:

On Sun, 30 Mar 2008 17:07:28 +0700, Bruce in Bangkok
wrote:

On Sat, 29 Mar 2008 21:59:03 -0700 (PDT), RichH
wrote:

Bruce is somewhat correct ... the tank has to be padded with an inert
gas such as Nitrogen, etc. Welders on transmission lines 'hot-tap'
repairs all the time ... just need someone who KNOWS how to weld
such.


The point about making a hot tap is that you are welding on a closed
pipe that is filled completely with oil - no air. some what different
then an empty tank.

I have no idea why the A.F. procedure was to steam the tank. Certainly
we had all kinds of inert gas available but that was the procedure.
Maybe because it worked?

In high school shop class, I had a lawnmower gas tank I wanted to
solder.

I washed the tank with host soapy water and let water run through it for
about ten minutes. I then waited for it to dry.

As soon as I hit it with the torch, kaboom and there went part of my
left eyebrow.

Lets not get to telling "welding and it blew up" stories. I've got a
couple that will make you cringe.

Bruce-in-Bangkok
(correct email address for reply)

On Sun, 30 Mar 2008 17:55:34 -0600, Paul Cassel
wrote:

WaIIy wrote:


In high school shop class, I had a lawnmower gas tank I wanted to
solder.

I washed the tank with host soapy water and let water run through it for
about ten minutes. I then waited for it to dry.

As soon as I hit it with the torch, kaboom and there went part of my
left eyebrow.


I thought when welding fuel tanks you leave them full of water when you
do the welding.


That is one theory but (1) you can't weld a portion of a normal (thin)
tank that is in contact with water as if you get 100 penetration your
filler metal comes in contact with the liquid and (2) if you are
welding above the water level there is room for explosive gasses to
accumulate.



Bruce-in-Bangkok
(correct email address for reply)

Bruce in Bangkok wrote:
On Sun, 30 Mar 2008 17:55:34 -0600, Paul Cassel

That is one theory but (1) you can't weld a portion of a normal (thin)
tank that is in contact with water as if you get 100 penetration your
filler metal comes in contact with the liquid and (2) if you are
welding above the water level there is room for explosive gasses to
accumulate.


I didn't envision it this way. I figured you welded a patch of similar
material to cover the hole much like a patch on an inner tube of your
bicycle. Thus you could lay a bead all around the patch effecting a
repair on a tank 100% filled with water.

I did some welding once but not on tanks. IIRC that was how the real
welders were doing it.

-paul

On Mon, 31 Mar 2008 08:52:20 -0600, Paul Cassel
wrote:

Bruce in Bangkok wrote:
On Sun, 30 Mar 2008 17:55:34 -0600, Paul Cassel

That is one theory but (1) you can't weld a portion of a normal (thin)
tank that is in contact with water as if you get 100 penetration your
filler metal comes in contact with the liquid and (2) if you are
welding above the water level there is room for explosive gasses to
accumulate.


I didn't envision it this way. I figured you welded a patch of similar
material to cover the hole much like a patch on an inner tube of your
bicycle. Thus you could lay a bead all around the patch effecting a
repair on a tank 100% filled with water.

I did some welding once but not on tanks. IIRC that was how the real
welders were doing it.

-paul


Depends on how you want to repair it. Welding a patch is fine, or
welding up the hole. But, having has a couple of things blow up on me
I think I'll stick to purging the tank in some manner before I weld
it. and I'm still kicking -- some people that tried welding tanks that
weren't properly purged aren't.




Bruce-in-Bangkok
(correct email address for reply)

On Mon, 31 Mar 2008 23:10:56 -0400, WaIIy wrote:

On Mon, 31 Mar 2008 12:49:10 +0700, Bruce in Bangkok
wrote:

On Sun, 30 Mar 2008 12:09:59 -0400, WaIIy wrote:

On Sun, 30 Mar 2008 17:07:28 +0700, Bruce in Bangkok
wrote:

On Sat, 29 Mar 2008 21:59:03 -0700 (PDT), RichH
wrote:

Bruce is somewhat correct ... the tank has to be padded with an inert
gas such as Nitrogen, etc. Welders on transmission lines 'hot-tap'
repairs all the time ... just need someone who KNOWS how to weld
such.


The point about making a hot tap is that you are welding on a closed
pipe that is filled completely with oil - no air. some what different
then an empty tank.

I have no idea why the A.F. procedure was to steam the tank. Certainly
we had all kinds of inert gas available but that was the procedure.
Maybe because it worked?

In high school shop class, I had a lawnmower gas tank I wanted to
solder.

I washed the tank with host soapy water and let water run through it for
about ten minutes. I then waited for it to dry.

As soon as I hit it with the torch, kaboom and there went part of my
left eyebrow.

Lets not get to telling "welding and it blew up" stories. I've got a
couple that will make you cringe.


We could tell a few "I just poured a little gas on the leaves"


It also makes a really great way to start the charcoal in a barbecue.

Bruce-in-Bangkok
(correct email address for reply)

On 29 Mar, 15:10, Marc Auslander
wrote:
I have a 20 year old diesel tank that has a small leak at or near a
bottom weld.

I've been thinking of taking it to a heliarc welder to attempt a
repair.

Comments?

gas explodes,if a tank is filled with liquid even desiel it will not
explode but the heat loss when welding can be a problem one solution
is to fill the tank with soap bubbles useig a soapy liquid and an air
line then weld a large patch on the bottom of the tank.