What was that welding exercise/exam?

Somewhere I read about a welding exercise where the student built a
tube frame of some sort, pressurized it, checked for leaks, then
smashed it flat and rechecked for leaks.
I've looked thru my books but can't find it. Anyone recall where I can
find a description of the exercise? - Mike

mhorowit wrote:
Somewhere I read about a welding exercise where the student built a
tube frame of some sort, pressurized it, checked for leaks, then
smashed it flat and rechecked for leaks.
I've looked thru my books but can't find it. Anyone recall where I can
find a description of the exercise? - Mike

Here is an idea:-

"Build a tube frame of some sort, pressurise it, check it
for leaks, then smash it flat and recheck for leaks."

Sorry - but you seem to have covered all of the
bases^H^H^H^H^H requirements already.

Oh, maybe you want to know how to interpret the results.
If it leaks you failed:-)

On 12 Jul 2006 04:58:49 -0700, "mhorowit" wrote:

Somewhere I read about a welding exercise where the student built a
tube frame of some sort, pressurized it, checked for leaks, then
smashed it flat and rechecked for leaks.
I've looked thru my books but can't find it. Anyone recall where I can
find a description of the exercise? - Mike

I have no idea what any official test looks like except a vague
recollection that the australian test was an N shape coming up off a
tube. you had to weld it bolted vertically up off a bench to
demonstrate welding in all positions. it was then sliced up to check
for carbon and impurities in the weld. there was also a set of butt
welds in sheet.

I have a friend who is a crackerjack welder but lacked the confidence
to tackle a welded tube airframe. even after he welded a tailwheel
that I flew across australia and back.
I had him weld up a square in tubing using a different type of joint
in each corner. he then stressed this to destruction in a press.
it took two tons to destroy each corner and the joint failure was in
the tubes a little way off beside the weld. with that reasurance he
has almost completed an absolutely schmick low wing sonerai two.

try it it worked for him.
Stealth Pilot

"mhorowit" wrote in message
oups.com...
| Somewhere I read about a welding exercise where the student built a
| tube frame of some sort, pressurized it, checked for leaks, then
| smashed it flat and rechecked for leaks.
| I've looked thru my books but can't find it. Anyone recall where I can
| find a description of the exercise? - Mike
|

My instructor had me butt weld some tubing in a vertical as well as a
horizonal position. Then grind off the weld until flush with the surface
of the tubing. Then cut the tubing into strips across the weld
approximately 3/8" wide. Then clamp each strip in a vise about an inch
away from the weld and bend the tubing back and forth until it breaks. A
break outside of the weld is a passing grade. A very humbling experience
at the time.

--
Jarhead




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"Jarhead" wrote

My instructor had me butt weld some tubing in a vertical as well as a
horizonal position. Then grind off the weld until flush with the surface
of the tubing. Then cut the tubing into strips across the weld
approximately 3/8" wide. Then clamp each strip in a vise about an inch
away from the weld and bend the tubing back and forth until it breaks. A
break outside of the weld is a passing grade. A very humbling experience
at the time.

The big thing missing with that exercise is checking for pinholes in the
weld, which would cause a leak. If the joint leaks, it lets moisture into
the inside of the tubes and promotes rust.

Some tube framed aerobatic aircraft have a pressure tap fitted to the tube
in a prominent place. The tubes are assembled with holes joining one tube
to the next. After welding, linseed oil is put inside the tubing (to
prevent rusting), then rotated around and drained out. The fuselage tubes
are then pressurized with nitrogen. If on the preflight, the pilot sees
that the gauge has dropped to zero, then he/she knows that there is a crack
in the frame somewhere, and to find it and fix it.

All in all, another very good way to make sure your airplane is not going to
fall apart, with you in it. That would be a "bad thing." g
--
Jim in NC

"Morgans" wrote in message
...

"Jarhead" wrote

My instructor had me butt weld some tubing in a vertical as well as a
horizonal position. Then grind off the weld until flush with the surface
of the tubing. Then cut the tubing into strips across the weld
approximately 3/8" wide. Then clamp each strip in a vise about an inch
away from the weld and bend the tubing back and forth until it breaks. A
break outside of the weld is a passing grade. A very humbling experience
at the time.

The big thing missing with that exercise is checking for pinholes in the
weld, which would cause a leak. If the joint leaks, it lets moisture into
the inside of the tubes and promotes rust.

Some tube framed aerobatic aircraft have a pressure tap fitted to the tube
in a prominent place. The tubes are assembled with holes joining one tube
to the next. After welding, linseed oil is put inside the tubing (to
prevent rusting), then rotated around and drained out. The fuselage tubes
are then pressurized with nitrogen. If on the preflight, the pilot sees
that the gauge has dropped to zero, then he/she knows that there is a
crack
in the frame somewhere, and to find it and fix it.

All in all, another very good way to make sure your airplane is not going
to
fall apart, with you in it. That would be a "bad thing." g
--
Jim in NC


Instead of filling with nitrogen, fill with argon while the frame is being
welded. This keeps the inside of the weld as clean as the outside. A low
flow rate is ample as it doesn't bleed to atmosphere as easily as the
outside of the tubing. The same pressure gauge will provide years of
confidence in the airframe integrity.

Stealth, send your welding samples to ETRS Pty. Ltd, 1 Acirl Street Ipswich
Qld, not sure of postcode. Their website http://www.etrs.com.au/ is being
updated at the moment, due to a company buyout, talk to Mike Lynham in
Ipswich about what samples are required for aircraft welding test. They will
destructively test and certify the welding.

Hope this helps,
Peter

mhorowit wrote:
Somewhere I read about a welding exercise where the student built a
tube frame of some sort, pressurized it, checked for leaks, then
smashed it flat and rechecked for leaks.
I've looked thru my books but can't find it. Anyone recall where I can
find a description of the exercise? - Mike

Take a 6 inch pipe. Fishmouth one end with 45 degree bevels, then keep
cutting all the way through the pipe along those same angles. Do it
again. Weld a shrader valve into one of the pieces, then weld the
whole thing (4 pieces) together. Does it hold air? Good. Now squash
it flat. If it still holds air, you can weld pressure vessels for
nuclear applications.

I could have the details a little off on the fabrication, but that's
the general scheme of it.