Conduit-- it's available everywhere.
You can get it for cheap from any hardware
store; you can get it for free from any abandoned
or not-so-abandoned building.
I want to weld these two pieces of conduit
together.
Problem: the structural steel that you want
it cladded in a very thin, very very toxic
layer of galvanization.
If I weld, they're probably going to stick,
but the galvanization will burn and boil off
and it will poison me.
Also it makes the weld not so great.
I'm going to show you how to get rid of the
galvanization thoroughly, effectively, and
quickly using a material that you can get
in any hardware store or have around the house.
Galvanization is a protective coating that's
laid down over steel to keep it from rusting.
It's a mix of different heavy metals, usually
zinc.
And you can tell if something is galvanized
when it has this dullish grey cast to it,
and secondly you can see a crystalline structure
in it, the way that it's laid down when it's
in the pickling bath or whatever they use
to galvanize.
One solution, and a solution that I've heard
from various metalworkers is take the metal
and grind it.
Things like conduit and most things that are
galvanized aren't just galvanized on the outside,
they're also galvanized on the inside.
How am I going to get a grinder into there?
It's going to be difficult, I'm going to be
there with a die grinder or a Dremel for hours.
Too much work.
Instead of using mechanical means to get the
galvanization off, I'm going to use chemical
means.
Materials needed: a plastic cup to hold everything
in, the metal that you want to remove the
galvanization from.
Since we're just stripping galv off the end,
just the part that we're going to weld, it
doesn't have to take the whole rod, just the
part that you need to work on.
Secondly, very importantly, muriatic acid.
It's a relatively dilute, like one third strength,
hydrochloric acid.
So, decently strong, but not super strong.
You can find it in any hardware store; it's
usually in the meth lab section.
And baking soda: a base to neutralize the
solution when we're all done.
I've got something to prop up my metal, in
this case it's a gas can.
I'm going to pour the acid in-- at this point
you might want some gloves or goggles.
What I like to do: I take a deep breath, I
stick the metal in the acid, and then I step
away.
A tale of heavy metal poisoning: I had this
really cool metal; it came from rooftop water
tanks.
I looked at it, and I didn't see any crystalline
structure on it, so I didn't think it was
galvanized.
And it had this dull reddishness to it that
I thought was a thin layer of rust.
Figured it was one of those steels like COR-TEN
or whatever that would just rust a little.
That night when I was welding I was shaking
and sweating; horrible fever like I've never
really had before.
Went to sleep, slept for 16 hours.
Later, I thought "Wait... maybe that metal
was galvanized, but in a way I haven't seen
before."
I had suffered whatever the final stage of
galvanization poisoning is.
The only other stage after that is death.
If I had done then what I'm showing you to
to do now, I probably wouldn't have screwed
up a couple of really important meetings,
I wouldn't have gotten horribly horribly ill,
and life in general would be a lot better.
So over here you can see a pretty sharp line--
that was the level of the acid.
Below that, it's just dull straight uncoated
steel.
It's already starting to oxidize, if I leave
it out for another twenty minutes it will
probably be red with rust.
Above there is a layer that I think it might
be degalvanized.
That's where the fumes from the acid rose
up, you can see it on this one.
And then up above that, straight up galvanized
metal.
Look at the color difference.
This: galvanized.
This: maybe galvanized, I don't think so,
and then this: bare steel.
I used the acid to get the galvanization off
the inside as well as the outside of the pipe,
now I need to get the acid off the inside
of the pipe.
So I'm making a solution of water and baking
soda, and then dip that in.
Muriatic acid: one of the things it's commonly
used for is cleaning cement.
If you dilute it out with water, especially
if you neutralize it first, you can dump it
down the drain.
You're no longer dumping down an acid, you're
dumping down a salt-- I'm not sure which salt
it is-- and water.
If you were to spill this on your workspace
floor or on your assistant, and you want to
neutralize it, just dump some baking soda
on it.
For example: oh no, a spill of acid!
Baking soda will fix it!
Ta-da, science!
After neutralizing the acid with baking soda,
I rinsed these off in the sink to clean them
off and you can see where it's already starting
to rust.
The galvanization is gone.
However the galvanization was gone very very
quickly, in just the violent part of the acid
reaction.
Later it just burbled burbled burbled slowly.
That slow burbling was the acid eating the
steel.
We left it in for longer than we should have,
and you can feel a ridge here in between the
original thickness and the thickness it was
eaten down to.
I know that's not just missing galvanization
since it's only a few molecules thick.
I'm just doing a quick and dirty join.
I'm not going to make it fancy, I'm not fish-mouthing
this to get a good, tight fit up, I'm just
sticking two pieces of metal together just
to show it will not boil out galvanization
and it should make a pretty decent weld.
Not the prettiest weld, but when you don't
fish-mouth tube, you have a lot of gap to
fill.
But the important thing is that it looks like
it will hold, there's no boiled away galvanization,
around it, there's no foaming, I didn't get
sick.
I've shown you how to degalvanize conduit
and turn something that's everywhere but kinda
useless into another useful thing.
If you want to see some real science... is
this one on camera?
Yeah.
Oh, science!
SCIENCE!
Science, acid bubbling next to a can of gasoline,
what could possibly go wrong?
Ahhh!
A cheap easy way to get kicked out of every
science fair!
"Sir, aren't you a little old to be in this
science fair?"
Don't get in the way of my knowledge, la la
la, security comes, then you burn them with
acid.
I'll show you who's science now...
