Welding question: joining an inner sleeve

Fortunat1 wrote:

I believe that you have to effectively have a full lap joint weld
between each outer tube and inner tube, AND the joint must be a
truncated cut and not just straight across in order to have sufficient
weld cross section since it's essential that the weld zone be much
stronger than the virgin metal up the tube.

The rosette welds done further up don't contribute that much strength
and are mostly (I believe) to prevent the inner tube from having an
unsupported length that allows "wiggling" of the inner tube in the
outer tube under stress. possibly leading to cracks in the main weld.



OK, I can buy all of that, but I don't know exactly what you mean by
truncated. Are you talking about the profile of the edges of the outer
tube, or do you mean the outer tube must be cut diaganally?


Look at it from a "stress riser" point of view.

A weld (I see what the problem is here - how to describe in words what
you are thinking in yer head)

Ok

If a welded tube is butted together with square cut ends (90 degree cut)
the weld will cause a sudden localized change in cross section - a
stress riser - something we try hard to avoid.

But lopping the tubes at 45 to 60 degrees spreads the "bump" in the
cross section of the weld across a longer distance.

Think of the weld bead as a "hard" spot. Angling the weld avoids having
a hard spot in a tiny localized area.


What John said about the rose on the inner tube is about what I recall.
Stabilize the inner tube and (again) avoid having the hard spot all
concentrated at the end of the inner sleeve (at the cluster).

FWIW?

Richard

On Thu, 20 Sep 2007 21:45:24 -0400, "J.Kahn"
wrote:


I believe that you have to effectively have a full lap joint weld
between each outer tube and inner tube, AND the joint must be a
truncated cut and not just straight across in order to have sufficient
weld cross section since it's essential that the weld zone be much
stronger than the virgin metal up the tube.

John


John - please see http://members.cox.net/mhorowit/cluster/lapjoint/
I took your suggestion and treated each side of the "outer sleeve" and
the "inner sleeve" as the components of a lap joint; hence two beads.
That's what you were talking about instead of my trying to integrate
the outer and inner sleeves in one weld, correct? - Mike

PS - I don't think taking a shortcut by simply cutting a partial
slice in a larger diameter tube would make a difference in the
exercise;

Michael Horowitz wrote:
On Thu, 20 Sep 2007 21:45:24 -0400, "J.Kahn"
wrote:


I believe that you have to effectively have a full lap joint weld
between each outer tube and inner tube, AND the joint must be a
truncated cut and not just straight across in order to have sufficient
weld cross section since it's essential that the weld zone be much
stronger than the virgin metal up the tube.

John


John - please see http://members.cox.net/mhorowit/cluster/lapjoint/
I took your suggestion and treated each side of the "outer sleeve" and
the "inner sleeve" as the components of a lap joint; hence two beads.
That's what you were talking about instead of my trying to integrate
the outer and inner sleeves in one weld, correct? - Mike

PS - I don't think taking a shortcut by simply cutting a partial
slice in a larger diameter tube would make a difference in the
exercise;

Sorry Michael, I went back over AC43.13 and realized I made a mistake.
Para 74 covers this type of weld repair where there is an inner splice
tube and it says to leave a 1/8" gap between the outer tubes of the
splice and then it simply says "Weld the inner sleeve to the tube stubs
through the 1/8" gap, forming a weld bead over the gap."

So you just do one bead, but make sure you get penetration down to the
lower layer. It really is just an elongated rosette weld.

The angle cut for the splice should be 30 deg for both a straight angle
cut (truncated) or fishmouth. Do not make splice joints straight across.

If you don't have AC43.13 handy I can scan the page that shows the
splice repair method.

To avoid that burnback notch at the open end of your slot if you have to
come to it at the end of the bead run instead of the start, stop the
bead about 1/4 inch from the end of the slot, so that you finish the
bead with the last 1/4" at the open end of the slot unwelded. Let the
piece cool off, then go back at it and quickly finish the unwelded
section. The burnback happens when trying to finish the weld to the end
while the whole piece is really hot after doing a long bead.

John

Fortunat1 wrote:
"J.Kahn" wrote in
:

Fortunat1 wrote:
clare at snyder.on.ca wrote in
news:r3k3f35vka26ss9jq6k80m2cr1ef67usun@ 4ax.com:

This is tubing, right? Drill a couple of holes and rosette weld, or
plug weld the sleave in place. It is now doing it's job Now weld the
ends of the tubes together. If the weld penetrates into the
re-enforcement sleave, good. If it doesn't the sleave is still in
there providing extra strength to the joint (done properly, the
joint is almost strong enough with just 4 plug welds per end)

This makes sense to me, however, looking in my books, it's stated
pretty clearly that the inner tube should be welded to the outers.
there's a copy of that text he

http://www2.tech.purdue.edu/at/cours...Links/Ac43-13-
1
B/CH4 _5.pdf

Now, it would seem to me that penetration of the inner tube would add
very little strength at all, particularly if it was a good snug fit.
Am I reading this wrong?

I believe that you have to effectively have a full lap joint weld
between each outer tube and inner tube, AND the joint must be a
truncated cut and not just straight across in order to have sufficient
weld cross section since it's essential that the weld zone be much
stronger than the virgin metal up the tube.

The rosette welds done further up don't contribute that much strength
and are mostly (I believe) to prevent the inner tube from having an
unsupported length that allows "wiggling" of the inner tube in the
outer tube under stress. possibly leading to cracks in the main weld.


OK, I can buy all of that, but I don't know exactly what you mean by
truncated. Are you talking about the profile of the edges of the outer
tube, or do you mean the outer tube must be cut diaganally?



The joints between the splice sections can be either a diagonal cut
(truncated) or fishmouth cut but never straight. In either case the cut
angle is 30 deg to the long axis of the tube.

John

"J.Kahn" wrote in news:xh0Ji.5443$RI4.28423
@wagner.videotron.net:

Fortunat1 wrote:
"J.Kahn" wrote in
:

Fortunat1 wrote:
clare at snyder.on.ca wrote in
news:r3k3f35vka26ss9jq6k80m2cr1ef67usun@ 4ax.com:

This is tubing, right? Drill a couple of holes and rosette weld,
or
plug weld the sleave in place. It is now doing it's job Now weld
the
ends of the tubes together. If the weld penetrates into the
re-enforcement sleave, good. If it doesn't the sleave is still in
there providing extra strength to the joint (done properly, the
joint is almost strong enough with just 4 plug welds per end)

This makes sense to me, however, looking in my books, it's stated
pretty clearly that the inner tube should be welded to the outers.
there's a copy of that text he

http://www2.tech.purdue.edu/at/cours...al_Links/Ac43-
13-
1
B/CH4 _5.pdf

Now, it would seem to me that penetration of the inner tube would
add
very little strength at all, particularly if it was a good snug
fit.
Am I reading this wrong?

I believe that you have to effectively have a full lap joint weld
between each outer tube and inner tube, AND the joint must be a
truncated cut and not just straight across in order to have
sufficient
weld cross section since it's essential that the weld zone be much
stronger than the virgin metal up the tube.

The rosette welds done further up don't contribute that much
strength
and are mostly (I believe) to prevent the inner tube from having an
unsupported length that allows "wiggling" of the inner tube in the
outer tube under stress. possibly leading to cracks in the main
weld.


OK, I can buy all of that, but I don't know exactly what you mean by
truncated. Are you talking about the profile of the edges of the
outer
tube, or do you mean the outer tube must be cut diaganally?



The joints between the splice sections can be either a diagonal cut
(truncated) or fishmouth cut but never straight. In either case the
cut
angle is 30 deg to the long axis of the tube.


Yep, I understand that OK. Just the way the word truncated was used I
thought it might have meant that the edge of the outer tube had to be
beveled or something, but surely this is not neccesary with .035 or .049
tubing anyway. I think I'm happy with the mechanics of it all.

F1

"J.Kahn" wrote in news:sf0Ji.5442$RI4.28304
@wagner.videotron.net:

Michael Horowitz wrote:
On Thu, 20 Sep 2007 21:45:24 -0400, "J.Kahn"
wrote:


I believe that you have to effectively have a full lap joint weld
between each outer tube and inner tube, AND the joint must be a
truncated cut and not just straight across in order to have
sufficient
weld cross section since it's essential that the weld zone be much
stronger than the virgin metal up the tube.

John


John - please see http://members.cox.net/mhorowit/cluster/lapjoint/
I took your suggestion and treated each side of the "outer sleeve"
and
the "inner sleeve" as the components of a lap joint; hence two beads.
That's what you were talking about instead of my trying to integrate
the outer and inner sleeves in one weld, correct? - Mike

PS - I don't think taking a shortcut by simply cutting a partial
slice in a larger diameter tube would make a difference in the
exercise;

Sorry Michael, I went back over AC43.13 and realized I made a mistake.
Para 74 covers this type of weld repair where there is an inner splice
tube and it says to leave a 1/8" gap between the outer tubes of the
splice and then it simply says "Weld the inner sleeve to the tube
stubs
through the 1/8" gap, forming a weld bead over the gap."

So you just do one bead, but make sure you get penetration down to the
lower layer. It really is just an elongated rosette weld.

The angle cut for the splice should be 30 deg for both a straight
angle
cut (truncated) or fishmouth. Do not make splice joints straight
across.

If you don't have AC43.13 handy I can scan the page that shows the
splice repair method.

To avoid that burnback notch at the open end of your slot if you have
to
come to it at the end of the bead run instead of the start, stop the
bead about 1/4 inch from the end of the slot, so that you finish the
bead with the last 1/4" at the open end of the slot unwelded. Let
the
piece cool off, then go back at it and quickly finish the unwelded
section. The burnback happens when trying to finish the weld to the
end
while the whole piece is really hot after doing a long bead.



Hope you don't mind me butting in here, but the photo that Michael put
up of that splice with the slit cut into the outer tube. Is anyone
suggesting that this is a good type of splice for some applications? I
can't see any inherent advantages in this as opposed to the diagonal
type. Or is this just an experiment in welding through a small gap in
the tubing?

"Fortunat1" wrote

Hope you don't mind me butting in here, but the photo that Michael put
up of that splice with the slit cut into the outer tube. Is anyone
suggesting that this is a good type of splice for some applications? I
can't see any inherent advantages in this as opposed to the diagonal
type. Or is this just an experiment in welding through a small gap in
the tubing?

If you do not make the slit and weld the inner to the outer, you are only
making the splice strong in STRAIGHT COMPRESSION, or STRAIGHT TENSION. You
have done nothing to marry the ENTIRE length of the two tubes together, so
they are strong in bending.

By only welding along the edge of the truncated or fishmouthed tube, you are
concentrating all of the bending to where the ends of where one tube meets
the other.

The slit is to spread all bending (and compression or tension) loads all
along the length of BOTH tubes.

Follow the picture he posted. That is the only recognized, strong and safe
way to make that type of splice. Any other treatment of the joint is not as
strong as it could be, and should be.

Again I say, AC43 is a time tested, an recognized way to do things,
especially in things such as splicing tubes. That technology has not been
changed in nearly 100 years. The methods contained in it are the right way
to do things, and were developed over many years of trial and error and
through experiment and testing.

Take the extra time to do what is suggested.
--
Jim in NC

"Morgans" wrote in
:

n welding
through a small gap in the tubing?

If you do not make the slit and weld the inner to the outer, you are
only making the splice strong in STRAIGHT COMPRESSION, or STRAIGHT
TENSION. You have done nothing to marry the ENTIRE length of the two
tubes together, so they are strong in bending.

By only welding along the edge of the truncated or fishmouthed tube,
you are concentrating all of the bending to where the ends of where
one tube meets the other.

The slit is to spread all bending (and compression or tension) loads
all along the length of BOTH tubes.

Follow the picture he posted. That is the only recognized, strong and
safe way to make that type of splice. Any other treatment of the
joint is not as strong as it could be, and should be.

Again I say, AC43 is a time tested, an recognized way to do things,
especially in things such as splicing tubes. That technology has not
been changed in nearly 100 years. The methods contained in it are the
right way to do things, and were developed over many years of trial
and error and through experiment and testing.

Take the extra time to do what is suggested.


Well, I can't find that type of repair anywhere in AC43. I also can't
see how it would contribute at all to the strength of a repair done
using the inner sleeve method. Even on the outer sleeve method, it only
states that a gap be left when the outer tube is split longitudinally.
when the outer tube is a snug fit, there doesn't even need to be rosette
welds... (I'm looking at and aound 4-38 here)

On Sep 22, 6:38 am, Fortunat1 wrote:
"Morgans" wrote :



n welding
through a small gap in the tubing?

If you do not make the slit and weld the inner to the outer, you are
only making the splice strong in STRAIGHT COMPRESSION, or STRAIGHT
TENSION. You have done nothing to marry the ENTIRE length of the two
tubes together, so they are strong in bending.

By only welding along the edge of the truncated or fishmouthed tube,
you are concentrating all of the bending to where the ends of where
one tube meets the other.

The slit is to spread all bending (and compression or tension) loads
all along the length of BOTH tubes.

Follow the picture he posted. That is the only recognized, strong and
safe way to make that type of splice. Any other treatment of the
joint is not as strong as it could be, and should be.

Again I say, AC43 is a time tested, an recognized way to do things,
especially in things such as splicing tubes. That technology has not
been changed in nearly 100 years. The methods contained in it are the
right way to do things, and were developed over many years of trial
and error and through experiment and testing.

Take the extra time to do what is suggested.

Well, I can't find that type of repair anywhere in AC43. I also can't
see how it would contribute at all to the strength of a repair done
using the inner sleeve method. Even on the outer sleeve method, it only
states that a gap be left when the outer tube is split longitudinally.
when the outer tube is a snug fit, there doesn't even need to be rosette
welds... (I'm looking at and aound 4-38 here)

You might have a really old version of AC43.13. You need
43.13-1B to reference it in section 4. The old 1A version has it in
Chapter 2, paragraph 74, Figure 2.7. The FAA website has it but I
haven't been able to get at it the last two days. They must be fixing
it. I hope.

Dan

On Sat, 22 Sep 2007 10:43:11 +0000 (UTC), Fortunat1 wrote:

"

Hope you don't mind me butting in here, but the photo that Michael put
up of that splice with the slit cut into the outer tube. Is anyone
suggesting that this is a good type of splice for some applications? I
can't see any inherent advantages in this as opposed to the diagonal
type. Or is this just an experiment in welding through a small gap in
the tubing?


OP here - what I was trying to do as easily as possible was to
duplicate the single part of the weld that would give me problems:
getting the inner metal molten without cooking the outer metal
sleeve. I simply cut an 1/8" slot in a piece of tubng, slipped the
inner tube in place and welded the two beads. Yes, I know why a real
weld would be along a 30^ angle, but that wasn't the point of the
exercise, which was to see how to run that bead, whether on the TE of
a split outer tube, or the gap proscribed for a splice by inner
sleeve. - Mike