From: kimberln@crl.com (J. Kimberlin)
Newsgroups: rec.crafts.metalworking
Subject: Re: Repairing small/pinholes in oil reservoir tank?
Date: 30 Jul 1996 17:01:27 -0700

In article <adamp.48.0B2C9C19@mcs.com>, Adam Pierce <adamp@mcs.com> wrote:
>>The only proper way to fix the tank is cut out the rusty
>>metal (where it is thin, of course) and then weld in
>>a replacement section.  While you have the tank open,
>>clean out as much rust as possible.
>	My question was always the same as the one that was raised; how 
>is an explosion prevented? The procedure is to keep a considerable 
>amount of gas in the tank so as to eliminate as much air space as possible. 
>The remaining air space is filled with an inert gas such as nitrogen this 
>works but is expensive so the shop would attach a hose to the exhaust pipe of 
>an old smoky engine and the other end to the gas tank and ran the engine for 
>about 15 minutes this eliminated enough oxygen to prevent any problems. This 
>technique sounds scary as hell but they have not blown themselves up in over 
>30 years of using this technique and I guess that they will keep on doing it 
>that way for at least the next 30.

I had some welding done once and at the shop, which was outside, there 
were a couple of gas tanks that needed repairs.  The gas tanks were first 
filled with hot water, left to sit for 10 minutes or so, then drained.  
Then, they would light a sheet of paper rolled up and give it to a guy who 
would run past the tank and shove the lighted paper into the filler 
nozzle.  The tanks I saw went *whump* and had 2 feet of flame, but did 
not distort.  Then the welder went at it with oxy-acet.  I was suitably 
scared sh*tless when I saw what they were going to do.  But evidently 
this was common practice.  The gasoline sold there was 72 octane - not 
very volatile, actually, and the altitude was 7600 feet.

Now, I have to say that I saw this in 1963 in Asmara, Eritrea which was 
part of Ethiopia at that time and not a separate country as it is today.
I don't know if this sort of activity has anything to do with being fleet 
of foot, but an Ethiopian lady won the marathon and an Ethiopian man is 
also doing good in the current olympics.  I'll bet their technique for 
welding gas tanks has not changed, and they are certainly good runners.

JerryK

From: Pete Albrecht
Newsgroups: rec.crafts.metalworking
Subject: Re: best way to clean old gas tank
Date: 13 Feb 1998 16:30:46 GMT

>I need to clean an old gas tank for reuse. It has some old gas in it
>now and it is removed.  The bottom is the only rusty area/ dirty.
>what chemical and/or process  is the best to clean this??


Typically you send it out to be "hot tanked," boiled in caustic soda. This will
remove all of the rust. It will also open any impending pinholes if the rust
has gone that far. It will also remove any tin coating on the inside which was
supposed to prevent rust in the first place.

For stuff like this I go to a very accomodating local auto radiator shop.

There are products available to recoat the inside of the tank but I would
consider those only as a last resort, if you have a tank with pinholes and the
rubbery solution may close it.

For a few pinholes, you can let a pro sweat brass patches onto the tank DON'T
DO THIS AT HOME!!! An empty gas tank is as close as most of us will ever get to
a bomb. There will be gasoline vapor inside no matter how well you try to rinse
or dry it! It comes out of the "pores" in the sheet metal. The pros, such as a
good radiator shop, can do this, usually by filling the tank with water or
inert gas while soldering.

Other solutions -- I have seen badly rusted tanks for rare cars repaired by
metal craftsmen, the kind of guys who make entire bodies from scratch. They cut
out the bottom, hammer out a new one complete with all the required ribs, and
butt weld it in place.

For some tanks, it may be possible to install a bladder, such as those used in
race cars. The tank then only acts as a holder for the rubber fuel tank inside.


If you want to try the PVC sloshing sealers, a company back east called Bill
Hirsch (advertises in Hemmings and other magazines) sells it, as does Eastwood.

Pete

From: Pete Albrecht
Newsgroups: rec.crafts.metalworking
Subject: Re: best way to clean old gas tank
Date: 13 Feb 1998 16:35:22 GMT

Oh, one thing I forgot to mention, one problem with the sloshing sealers is
that they may be affected by alcohol in the gasoline, and right now, out here
in CA, all of our gas has junk like that in it (like watering down drinks and
then charging extra for it). Don't know if "oxygenated fuels" have gone
nationwide yet.

Pete

From: "David Rouse" <drouse@pacbell.net>
Newsgroups: rec.crafts.metalworking
Subject: Re: best way to clean old gas tank
Date: 14 Feb 1998 12:21:27 GMT

PLAlbrecht <plalbrecht@aol.com> wrote in article
<19980213163001.LAA03022@ladder03.news.aol.com>...
>>I need to clean an old gas tank for reuse. It has some old gas in it
>>now and it is removed. The bottom is the only rusty area/ dirty. what
>>chemical and/or process is the best to clean this??
>
>Typically you send it out to be "hot tanked," boiled in caustic soda.
>This will remove all of the rust. It will also open any impending
>pinholes if the rust has gone that far. It will also remove any tin
>coating on the inside which was supposed to prevent rust in the first
>place.

I have used off the shelf heavy-duty radiator cleaner with good
results if the corrosion isn't too bad. Mix it strong with very hot
water and stick an air line in for agitation. The best results though
I achieved using a commercial floor cleaner made by ZEP. A friend of
mine was restoring an early 60's MG and the tank had sat for about 10
years with gas in it. The cleaner used potassium hydroxide as the
active ingredient. It took two applications to get it to a usable
condition. I have found that basic solutions work better than acidic
ones. If you use something with a really strong pH, be kind to your
sewage treatment plant and reduce it to a neutral pH before sending
down the tubes.

>There are products available to recoat the inside of the tank but I would
>consider those only as a last resort, if you have a tank with pinholes
>and the rubbery solution may close it.

The coating that I have used was epoxy based and is damned near
impervious to anything. I live in Ca. and the 'additives' don't seem
to phase it at all and it has been about four years now since I
coated the tank on my Honda.

>For a few pinholes, you can let a pro sweat brass patches onto the tank
>DON'T DO THIS AT HOME!!! An empty gas tank is as close as most of us will
>ever get to a bomb. There will be gasoline vapor inside no matter how
>well you try to rinse or dry it! It comes out of the "pores" in the sheet
>metal.

Now this is simply not true. After the tank has been cleaned, rinsed
and dried there will not be enough residue to constitute a hazard.
Scale and corrosion will asorb gas and will keep releasing it despite
attempts to thoroughly dry it, clean metal will not. A cheap and
dirty way to deal with pinholes is to clean the metal on the outside
of the tank where the pinhole is and use a panhead sheetmetal screw
with a gas resistant rtv sealant.

From: Pete Albrecht
Newsgroups: rec.crafts.metalworking
Subject: Re: best way to clean old gas tank
Date: 15 Feb 1998 20:55:38 GMT

I wrote

>>There will be gasoline vapor inside no matter how well you try to rinse
>>or dry it! It comes out of the "pores" in the sheet metal.

David Rouse wrote
>Now this is simply not true. After the tank has been cleaned, rinsed
>and dried there will not be enough residue to constitute a hazard.
>Scale and corrosion will asorb gas and will keep releasing it despite
>attempts to thoroughly dry it, clean metal will not.

RIght. I meant that there will still be vapor inside an otherwise untreated
tank (not boiled out etc. ) Don't try to weld or solder a tank that has merely
been rinsed out and dried, there will still be gasoline vapor inside. (Your
nose will tell you that...) But boiling it out will remove the remaining gas
vapor.

Pete

From: Pete Albrecht
Newsgroups: rec.crafts.metalworking
Subject: Re: best way to clean old gas tank
Date: 15 Feb 1998 20:59:53 GMT

Peter Drumm wrote
>The radiator shops here quit doing gas(and diesel fuel) tanks some
>time ago. For $95-$100 you can get a brand new tank for almost any
>car/PU, repairs can easily cost that much.

Shops here in southern California still do it. There are even businesses that
do nothing but strip auto sheetmetal, including tanks. (Redi-Strip franchises,
etc.)

Tanks aren't available for all cars. I work on old Porsches, and tanks for
those can go from $250 for a decent usable ordinary tank to $1000 for the
80-liter 356 Carrera/GT racing tank. So in this case, and for other old
limited-production cars, cleaning and fixing the tank makes sense.

Pete

From: Pete Albrecht
Newsgroups: rec.crafts.metalworking
Subject: Re: best way to clean old gas tank
Date: 18 Feb 1998 04:09:30 GMT

M. Kinsler wrote

>I'm also thinking of
>trying to take existing tanks of some sort--air tanks, or whatever--and
>coupling them together with fuel-resistant hose to make an ersatz tank
>with perhaps a larger capacity than my current 14 gallons.

Aw, think BIG, man... go find a copy of Brock Yates' (he of Car & Driver
Magazine fame) "Sunday Driver", written back in the early 1970s. As I recall
the story, they were pre-running the original One Lap of America (aka the
Cannonball Baker Sea to Shining Sea Trophy Dash) in a Dodge van, fitted with an
old heating oil tank. I don't know how many gallons those things take but the
joke was that if they ever had an accident, you would see the fireball for
about three states in any direction. The plan was to run from NY to LA nonstop.
Almost made it. Had to stop in Flagstaff for gas. In the days of full-service
stations. "Gee, mister, how much does this thing TAKE?"

Pete
survivor of the 1989 One Lap of America aboard a Lamborghini truck,
ferchrissakes.