Holes in welded and galvanised structures
 

I've been looking at a few welded structures made from tubular steel and galvanised. They often include open holes (see pictures below). Anyone know why? I could make a few guesses but I'm not certain.

https://www.flickr.com/photos/138493...posted-public/
https://www.flickr.com/photos/138493...posted-public/

Chris

Holes in welded and galvanised structures
 

On Thu, 5 Oct 2017 15:56:04 -0700 (PDT), Christopher Tidy
wrote:

I've been looking at a few welded structures made from tubular steel and galvanised. They often include open holes (see pictures below). Anyone know why? I could make a few guesses but I'm not certain.

https://www.flickr.com/photos/138493...posted-public/
https://www.flickr.com/photos/138493...posted-public/

Chris


Yes indeed.

They didnt bother to patch up the holes from the previous uses of the
steel before it was salvaged and reused.

Nothing more.


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Holes in welded and galvanised structures
 

Am Freitag, 6. Oktober 2017 00:59:22 UTC+2 schrieb Gunner Asch:

Yes indeed.

They didnt bother to patch up the holes from the previous uses of the
steel before it was salvaged and reused.

Nothing more.

But the holes are always of a similar size and always occur near the welded joints?

Holes in welded and galvanised structures
 

On 05/10/17 23:56, Christopher Tidy wrote:
I've been looking at a few welded structures made from tubular steel and galvanised. They often include open holes (see pictures below). Anyone know why? I could make a few guesses but I'm not certain.

https://www.flickr.com/photos/138493...posted-public/
https://www.flickr.com/photos/138493...posted-public/

Chris

Items that are hot dip galvanised have to be vented in order to prevent
dangerous pressure build-up, I've had many items dipped and it is a good
processÂ* but theÂ* sections need to be vented to relieve the pressure
build up .

Holes in welded and galvanised structures
 

Am Freitag, 6. Oktober 2017 02:00:24 UTC+2 schrieb David Billington:

Items that are hot dip galvanised have to be vented in order to prevent
dangerous pressure build-up, I've had many items dipped and it is a good
processÂ* but theÂ* sections need to be vented to relieve the pressure
build up.

Makes sense. Not what I guessed, though. I was guessing it was to prevent stagnant water from building up inside the tubes and causing corrosion.

Holes in welded and galvanised structures
 

On 2017-10-06, Christopher Tidy wrote:
Am Freitag, 6. Oktober 2017 02:00:24 UTC+2 schrieb David Billington:

Items that are hot dip galvanised have to be vented in order to prevent
dangerous pressure build-up, I've had many items dipped and it is a good
process* but the* sections need to be vented to relieve the pressure
build up.

Makes sense. Not what I guessed, though. I was guessing it was to
prevent stagnant water from building up inside the tubes and causing
corrosion.

Even if it were not galvanized, there is another reason to do
it. When I was welding up some tubing to make a support for a corner
notcher I started with a top rectangular frame with three sides milled
off each end of two of the four sides, leaving a flap which covered the
open end of the other two tubes. I drilled holes in each of the
un-flapped tubes to vent into the flapped ones, plus holes to vent into
the following upright legs. The reason for this was I expected
expansion of the air trapped in the tubes, and when welding that could
blow the fill material (Tig welding, FWIW) out of some of the joints.
Give it vents, and you won't have expanding air pushing out the melted
metal and weakening the joints.

Later tubes joining the legs part way down were also drilled on
the underside to avoid similar air induced holes.

Enjoy,
DoN.

--
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Holes in welded and galvanised structures
 

On Thu, 5 Oct 2017 16:47:41 -0700 (PDT), Christopher Tidy
wrote:

Am Freitag, 6. Oktober 2017 00:59:22 UTC+2 schrieb Gunner Asch:

Yes indeed.

They didnt bother to patch up the holes from the previous uses of the
steel before it was salvaged and reused.

Nothing more.

But the holes are always of a similar size and always occur near the welded joints?

Luck?


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Holes in welded and galvanised structures
 

On Thu, 5 Oct 2017 15:56:04 -0700 (PDT), Christopher Tidy
wrote:

I've been looking at a few welded structures made from tubular steel and galvanised. They often include open holes (see pictures below). Anyone know why? I could make a few guesses but I'm not certain.

https://www.flickr.com/photos/138493...posted-public/
https://www.flickr.com/photos/138493...posted-public/

Chris
https://www.galvanizeit.org/design-a...g-and-drainage

Holes in welded and galvanised structures
 

On 06/10/17 01:10, Christopher Tidy wrote:
Am Freitag, 6. Oktober 2017 02:00:24 UTC+2 schrieb David Billington:

Items that are hot dip galvanised have to be vented in order to prevent
dangerous pressure build-up, I've had many items dipped and it is a good
processÂ* but theÂ* sections need to be vented to relieve the pressure
build up.
Makes sense. Not what I guessed, though. I was guessing it was to prevent stagnant water from building up inside the tubes and causing corrosion.

Here is a venting guidance video from Wedge Galvanising
http://www.youtube.com/watch?v=C8EGUlerwVg , it include brief footage of
what can happen when an unvented items is dipped and it bursts.

Holes in welded and galvanised structures
 

Am Freitag, 6. Oktober 2017 12:25:31 UTC+2 schrieb David Billington:

Here is a venting guidance video from Wedge Galvanising
http://www.youtube.com/watch?v=C8EGUlerwVg , it include brief footage of
what can happen when an unvented items is dipped and it bursts.

Great video. It explains a lot of small structural features on fabricated structures. Thanks to everyone for the responses. Interesting thread.

By the way, does anyone know why the cut-out on this excavator dipper is provided? I figure it might be something to do with stress distribution and fatigue resistance, but I can't work out why this cut-out location would help. Maybe it has another purpose. Any ideas?

https://www.flickr.com/photos/138493...posted-public/

Holes in welded and galvanised structures
 

Am Freitag, 6. Oktober 2017 12:25:31 UTC+2 schrieb David Billington:

Here is a venting guidance video from Wedge Galvanising
http://www.youtube.com/watch?v=C8EGUlerwVg , it include brief footage of
what can happen when an unvented items is dipped and it bursts.

By the way, I was told lately that galvanising sticks better if the steel surface is slightly corroded. Anyone know if this is true?

Holes in welded and galvanised structures
 

On 06/10/17 12:10, Christopher Tidy wrote:
Am Freitag, 6. Oktober 2017 12:25:31 UTC+2 schrieb David Billington:

Here is a venting guidance video from Wedge Galvanising
http://www.youtube.com/watch?v=C8EGUlerwVg , it include brief footage of
what can happen when an unvented items is dipped and it bursts.
By the way, I was told lately that galvanising sticks better if the steel surface is slightly corroded. Anyone know if this is true?

Possibly the corrosion leads to a rougher surface which results in a
thicker zinc coating. Items are intentional roughened by sand blasting
for that reason.

Holes in welded and galvanised structures
 

Am Freitag, 6. Oktober 2017 13:17:30 UTC+2 schrieb David Billington:

Possibly the corrosion leads to a rougher surface which results in a
thicker zinc coating. Items are intentional roughened by sand blasting
for that reason.

That makes sense, especially among guys who are keen to save money.

Holes in welded and galvanised structures
 

On 06/10/17 12:33, Christopher Tidy wrote:
Am Freitag, 6. Oktober 2017 13:17:30 UTC+2 schrieb David Billington:

Possibly the corrosion leads to a rougher surface which results in a
thicker zinc coating. Items are intentional roughened by sand blasting
for that reason.
That makes sense, especially among guys who are keen to save money.

I don't know if it would save money as my understanding is you pay by
the weight of zinc added. It's a very effective bulk process and my
neighbour priced up galvanising versus painting in his former job at
Hanson and the galvanisingÂ* was cheaper and more effective, the paint
system if used would have required sandblasting the steelwork anyway.
The galvanising didn't require sandblasting but it may have been done
for extra protection, the initial acid dip removes any rust and mill
scale anyway.

Holes in welded and galvanised structures
 

Am Freitag, 6. Oktober 2017 13:45:23 UTC+2 schrieb David Billington:

I don't know if it would save money as my understanding is you pay by
the weight of zinc added. It's a very effective bulk process and my
neighbour priced up galvanising versus painting in his former job at
Hanson and the galvanisingÂ* was cheaper and more effective, the paint
system if used would have required sandblasting the steelwork anyway.
The galvanising didn't require sandblasting but it may have been done
for extra protection, the initial acid dip removes any rust and mill
scale anyway.

Maybe it's just a way to save on the cost of the sandblasting to roughen the surface.

Holes in welded and galvanised structures
 

On Fri, 6 Oct 2017 12:45:20 +0100, David Billington
wrote:

On 06/10/17 12:33, Christopher Tidy wrote:
Am Freitag, 6. Oktober 2017 13:17:30 UTC+2 schrieb David Billington:

Possibly the corrosion leads to a rougher surface which results in a
thicker zinc coating. Items are intentional roughened by sand blasting
for that reason.
That makes sense, especially among guys who are keen to save money.

I don't know if it would save money as my understanding is you pay by
the weight of zinc added. It's a very effective bulk process and my
neighbour priced up galvanising versus painting in his former job at
Hanson and the galvanising* was cheaper and more effective, the paint
system if used would have required sandblasting the steelwork anyway.
The galvanising didn't require sandblasting but it may have been done
for extra protection, the initial acid dip removes any rust and mill
scale anyway.

In high-volume commercial galzanizing, the steel is prepped with a
zinc ammonium chloride bath. Chemistry is not my thing but I think
it's actually a conversion coating that cleans the surface and leaves
a protective film of the conversion product on the steel.

Even slight oxidation of the steel weakens adhesion of the zinc.

--
Ed Huntress

Holes in welded and galvanised structures
 

On Fri, 6 Oct 2017 04:51:30 -0700 (PDT), Christopher Tidy
wrote:

Am Freitag, 6. Oktober 2017 13:45:23 UTC+2 schrieb David Billington:

I don't know if it would save money as my understanding is you pay by
the weight of zinc added. It's a very effective bulk process and my
neighbour priced up galvanising versus painting in his former job at
Hanson and the galvanising* was cheaper and more effective, the paint
system if used would have required sandblasting the steelwork anyway.
The galvanising didn't require sandblasting but it may have been done
for extra protection, the initial acid dip removes any rust and mill
scale anyway.

Maybe it's just a way to save on the cost of the sandblasting to roughen the surface.

As I think about it, that "high-volume" treatment I mentioned may
apply only to galvanizing steel strip in a continuous process. That's
where I learned about it, when I was reporting on making car body
panels.

I see that the American Galvanizer's Assn. has much more info, which
probably applies to fabricated structures and parts:

https://www.galvanizeit.org/educatio...to-galvanizing

--
Ed Huntress

Holes in welded and galvanised structures
 

On 06/10/17 12:55, Ed Huntress wrote:
On Fri, 6 Oct 2017 12:45:20 +0100, David Billington
wrote:

On 06/10/17 12:33, Christopher Tidy wrote:
Am Freitag, 6. Oktober 2017 13:17:30 UTC+2 schrieb David Billington:

Possibly the corrosion leads to a rougher surface which results in a
thicker zinc coating. Items are intentional roughened by sand blasting
for that reason.
That makes sense, especially among guys who are keen to save money.
I don't know if it would save money as my understanding is you pay by
the weight of zinc added. It's a very effective bulk process and my
neighbour priced up galvanising versus painting in his former job at
Hanson and the galvanisingÂ* was cheaper and more effective, the paint
system if used would have required sandblasting the steelwork anyway.
The galvanising didn't require sandblasting but it may have been done
for extra protection, the initial acid dip removes any rust and mill
scale anyway.
In high-volume commercial galzanizing, the steel is prepped with a
zinc ammonium chloride bath. Chemistry is not my thing but I think
it's actually a conversion coating that cleans the surface and leaves
a protective film of the conversion product on the steel.

Even slight oxidation of the steel weakens adhesion of the zinc.

For the stuff I've had done the first stage is the acid dip to remove
mill scale and rust, the 2nd bath is as you mention, and the 3rd stage
is the dip in the molten zinc.

Holes in welded and galvanised structures
 

On 06/10/17 12:04, Christopher Tidy wrote:
Am Freitag, 6. Oktober 2017 12:25:31 UTC+2 schrieb David Billington:

Here is a venting guidance video from Wedge Galvanising
http://www.youtube.com/watch?v=C8EGUlerwVg , it include brief footage of
what can happen when an unvented items is dipped and it bursts.
Great video. It explains a lot of small structural features on fabricated structures. Thanks to everyone for the responses. Interesting thread.

By the way, does anyone know why the cut-out on this excavator dipper is provided? I figure it might be something to do with stress distribution and fatigue resistance, but I can't work out why this cut-out location would help. Maybe it has another purpose. Any ideas?

https://www.flickr.com/photos/138493...posted-public/

I've been told that the start and stop of a weld is where fractures are
most likely to start and that on equipment such as that the welds are
intentionally started and stopped in a low stress region so it may be
that the hole in the centre of the weldment is where that happens.

Holes in welded and galvanised structures
 

Christopher Tidy wrote:

Am Freitag, 6. Oktober 2017 02:00:24 UTC+2 schrieb David Billington:

Items that are hot dip galvanised have to be vented in order to prevent
dangerous pressure build-up, I've had many items dipped and it is a good
process but the sections need to be vented to relieve the pressure
build up.

Makes sense. Not what I guessed, though. I was guessing it was to prevent
stagnant water from building up inside the tubes and causing corrosion.
If a closed segment had some water left in it by accident, and then you
welded on it, it could explode. Some people have apparently been killed in
such explosions, or horribly burned by flying molten metal.

Theoretically, this could happen just from trapped air, too.

Jon

Holes in welded and galvanised structures
 

On Fri, 6 Oct 2017 11:25:27 +0100, David Billington
wrote:

On 06/10/17 01:10, Christopher Tidy wrote:
Am Freitag, 6. Oktober 2017 02:00:24 UTC+2 schrieb David Billington:

Items that are hot dip galvanised have to be vented in order to prevent
dangerous pressure build-up, I've had many items dipped and it is a good
process* but the* sections need to be vented to relieve the pressure
build up.
Makes sense. Not what I guessed, though. I was guessing it was to prevent stagnant water from building up inside the tubes and causing corrosion.

Here is a venting guidance video from Wedge Galvanising
http://www.youtube.com/watch?v=C8EGUlerwVg , it include brief footage of
what can happen when an unvented items is dipped and it bursts.

I hope they had the customer sign that he had drilled vent holes, so
he can pay for it instead of them. Messy! 840F/449C expands air a
bit, I'm guessing.

--
However beautiful the strategy, you should occasionally look at the results.
-- Sir Winston Churchill

Holes in welded and galvanised structures
 

On 06/10/17 20:51, Larry Jaques wrote:
On Fri, 6 Oct 2017 11:25:27 +0100, David Billington
wrote:

On 06/10/17 01:10, Christopher Tidy wrote:
Am Freitag, 6. Oktober 2017 02:00:24 UTC+2 schrieb David Billington:

Items that are hot dip galvanised have to be vented in order to prevent
dangerous pressure build-up, I've had many items dipped and it is a good
processÂ* but theÂ* sections need to be vented to relieve the pressure
build up.
Makes sense. Not what I guessed, though. I was guessing it was to prevent stagnant water from building up inside the tubes and causing corrosion.

Here is a venting guidance video from Wedge Galvanising
http://www.youtube.com/watch?v=C8EGUlerwVg , it include brief footage of
what can happen when an unvented items is dipped and it bursts.
I hope they had the customer sign that he had drilled vent holes, so
he can pay for it instead of them. Messy! 840F/449C expands air a
bit, I'm guessing.

--
However beautiful the strategy, you should occasionally look at the results.
-- Sir Winston Churchill

I suspect they missed that one as the galvanisers I've used will drill
holes at their discretion if they feel it isn't appropriately vented.

Holes in welded and galvanised structures
 

On Fri, 6 Oct 2017 11:25:27 +0100, David Billington
wrote:

On 06/10/17 01:10, Christopher Tidy wrote:
Am Freitag, 6. Oktober 2017 02:00:24 UTC+2 schrieb David Billington:

Items that are hot dip galvanised have to be vented in order to prevent
dangerous pressure build-up, I've had many items dipped and it is a good
process* but the* sections need to be vented to relieve the pressure
build up.
Makes sense. Not what I guessed, though. I was guessing it was to prevent stagnant water from building up inside the tubes and causing corrosion.

Here is a venting guidance video from Wedge Galvanising
http://www.youtube.com/watch?v=C8EGUlerwVg , it include brief footage of
what can happen when an unvented items is dipped and it bursts.


Thanks! Taught me lots of stuff!

Much obliged!


---
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Holes in welded and galvanised structures
 

Interesting. How about these holes and weld tails (see below)? These must be for additional strength and fatigue resistance, right?

https://www.flickr.com/photos/138493...posted-public/
https://www.flickr.com/photos/138493...posted-public/

Chris

Holes in welded and galvanised structures
 

On Sun, 8 Oct 2017 16:09:44 -0700 (PDT), Christopher Tidy
wrote:

Interesting. How about these holes and weld tails (see below)? These must be for additional strength and fatigue resistance, right?

Must be.


https://www.flickr.com/photos/138493...posted-public/
https://www.flickr.com/photos/138493...posted-public/

Fascinating that the part has 3 weld tails and no (visible) welding on
the bottom left side. Those tabs are under extremely high pressure as
pivot points. Historical failure surely led to this practice. I'll
bet Caterpillar, Kubota, Case, Hitachi, Komatsu, Volvo, etc. engineers
have some stories to tell about them. If you write to them and they
respond, please share it with us. I always got Gibbs-slapped as a kid
because I constantly asked for more details about everything.

-
I've figured out why we have Dems. Uncle Siggy told me:

Most people do not really want freedom, because freedom involves
responsibility, and most people are frightened of responsibility.
--Sigmund Freud

Unfortunately, some Reps are that way, too. (see CONgress)

Holes in welded and galvanised structures
 

"Larry Jaques" wrote in message
...
On Sun, 8 Oct 2017 16:09:44 -0700 (PDT), Christopher Tidy
wrote:

Interesting. How about these holes and weld tails (see below)? These
must be for additional strength and fatigue resistance, right?

Must be.


https://www.flickr.com/photos/138493...posted-public/
https://www.flickr.com/photos/138493...posted-public/

Fascinating that the part has 3 weld tails and no (visible) welding
on
the bottom left side. Those tabs are under extremely high pressure
as
pivot points. Historical failure surely led to this practice. I'll
bet Caterpillar, Kubota, Case, Hitachi, Komatsu, Volvo, etc.
engineers
have some stories to tell about them. If you write to them and they
respond, please share it with us. I always got Gibbs-slapped as a
kid
because I constantly asked for more details about everything.


Before computers the practice was to design as carefully as existing
theory and manual calculation permitted and then test to destruction.
WW2 aircraft engines that had to be as light (=weak) as possible are a
good example.
http://spitfiresite.com/2010/04/the-...in-engine.html
"Only 175 had been built and these were considered to be rather
unreliable. As a result, Rolls-Royce introduced an ambitious
reliability-improvement programme to fix the problems. This consisted
of taking random engines from the end of assembly line and running
them continuously at full power until they failed. Each was then
dismantled to find out which part had failed, and that part was
redesigned to be stronger. After two years of this programme the
Merlin had matured into one of the most reliable aero engines in the
world, and could sustain eight-hour combat missions with no problems."

These overly optimistic submarine engine designs were never perfected:
https://oldmachinepress.com/2014/08/...diesel-engine/
"The 16-338 engines proved somewhat unreliable in service and required
excessive maintenance. Some of the 16-338's issues were due to the
Navy using standard diesel lubricating oil rather than the special oil
specified for use in the engine. Ultimately, the Tench- and Tang-class
submarines were re-engined and their 16-338 parts were used as spares
to keep the USS Albacore running until it was withdrawn from service
in 1972."

It was withdrawn from service when the supply of spares ran out. I
happened to visit the Albacore when the Navy Yard's retired chief
engineer was aboard to prepare for a film crew.

The Navy's opinion was that the crankcase was too lightly built and
flexed excessively.

https://en.wikipedia.org/wiki/Hooven-Owens-Rentschler
It was originally a German design that didn't work out well for them
either.

-jsw

Holes in welded and galvanised structures
 

On Mon, 9 Oct 2017 10:34:08 -0400, "Jim Wilkins"
wrote:

"Larry Jaques" wrote in message
.. .
On Sun, 8 Oct 2017 16:09:44 -0700 (PDT), Christopher Tidy
wrote:

Interesting. How about these holes and weld tails (see below)? These
must be for additional strength and fatigue resistance, right?

Must be.


https://www.flickr.com/photos/138493...posted-public/
https://www.flickr.com/photos/138493...posted-public/

Fascinating that the part has 3 weld tails and no (visible) welding
on
the bottom left side. Those tabs are under extremely high pressure
as
pivot points. Historical failure surely led to this practice. I'll
bet Caterpillar, Kubota, Case, Hitachi, Komatsu, Volvo, etc.
engineers
have some stories to tell about them. If you write to them and they
respond, please share it with us. I always got Gibbs-slapped as a
kid
because I constantly asked for more details about everything.


Before computers the practice was to design as carefully as existing
theory and manual calculation permitted and then test to destruction.
WW2 aircraft engines that had to be as light (=weak) as possible are a
good example.
http://spitfiresite.com/2010/04/the-...in-engine.html
"Only 175 had been built and these were considered to be rather
unreliable. As a result, Rolls-Royce introduced an ambitious
reliability-improvement programme to fix the problems. This consisted
of taking random engines from the end of assembly line and running
them continuously at full power until they failed. Each was then
dismantled to find out which part had failed, and that part was
redesigned to be stronger. After two years of this programme the
Merlin had matured into one of the most reliable aero engines in the
world, and could sustain eight-hour combat missions with no problems."

In the early decades of the last century, that's how Rolls-Royce
developed their automobile engines, too.

Royce took measurements from the best engines of the day and then
averaged them. That's how he arrived at, for example, the odd
bore/stroke dimensions of their early engines.

The 1904 Grey Ghost was developed that way. To this day, many
historical automobile experts consider it to be the best engine for
its day, of all time.

The bar was rather low in 1904, however. d8-)

--
Ed Huntress

Holes in welded and galvanised structures
 

"Ed Huntress" wrote in message
...
On Mon, 9 Oct 2017 10:34:08 -0400, "Jim Wilkins"
wrote:

"Larry Jaques" wrote in message
. ..
On Sun, 8 Oct 2017 16:09:44 -0700 (PDT), Christopher Tidy
wrote:

Interesting. How about these holes and weld tails (see below)?
These
must be for additional strength and fatigue resistance, right?

Must be.


https://www.flickr.com/photos/138493...posted-public/
https://www.flickr.com/photos/138493...posted-public/

Fascinating that the part has 3 weld tails and no (visible)
welding
on
the bottom left side. Those tabs are under extremely high
pressure
as
pivot points. Historical failure surely led to this practice.
I'll
bet Caterpillar, Kubota, Case, Hitachi, Komatsu, Volvo, etc.
engineers
have some stories to tell about them. If you write to them and
they
respond, please share it with us. I always got Gibbs-slapped as a
kid
because I constantly asked for more details about everything.


Before computers the practice was to design as carefully as existing
theory and manual calculation permitted and then test to
destruction.
WW2 aircraft engines that had to be as light (=weak) as possible are
a
good example.
http://spitfiresite.com/2010/04/the-...in-engine.html
"Only 175 had been built and these were considered to be rather
unreliable. As a result, Rolls-Royce introduced an ambitious
reliability-improvement programme to fix the problems. This
consisted
of taking random engines from the end of assembly line and running
them continuously at full power until they failed. Each was then
dismantled to find out which part had failed, and that part was
redesigned to be stronger. After two years of this programme the
Merlin had matured into one of the most reliable aero engines in the
world, and could sustain eight-hour combat missions with no
problems."

In the early decades of the last century, that's how Rolls-Royce
developed their automobile engines, too.

Royce took measurements from the best engines of the day and then
averaged them. That's how he arrived at, for example, the odd
bore/stroke dimensions of their early engines.

The 1904 Grey Ghost was developed that way. To this day, many
historical automobile experts consider it to be the best engine for
its day, of all time.

The bar was rather low in 1904, however. d8-)

--
Ed Huntress

https://www.wired.com/2010/03/boeing...ing-flex-test/

-jsw

Holes in welded and galvanised structures
 

On Mon, 9 Oct 2017 12:23:38 -0400, "Jim Wilkins"
wrote:

"Ed Huntress" wrote in message
.. .
On Mon, 9 Oct 2017 10:34:08 -0400, "Jim Wilkins"
wrote:

"Larry Jaques" wrote in message
...
On Sun, 8 Oct 2017 16:09:44 -0700 (PDT), Christopher Tidy
wrote:

Interesting. How about these holes and weld tails (see below)?
These
must be for additional strength and fatigue resistance, right?

Must be.


https://www.flickr.com/photos/138493...posted-public/
https://www.flickr.com/photos/138493...posted-public/

Fascinating that the part has 3 weld tails and no (visible)
welding
on
the bottom left side. Those tabs are under extremely high
pressure
as
pivot points. Historical failure surely led to this practice.
I'll
bet Caterpillar, Kubota, Case, Hitachi, Komatsu, Volvo, etc.
engineers
have some stories to tell about them. If you write to them and
they
respond, please share it with us. I always got Gibbs-slapped as a
kid
because I constantly asked for more details about everything.


Before computers the practice was to design as carefully as existing
theory and manual calculation permitted and then test to
destruction.
WW2 aircraft engines that had to be as light (=weak) as possible are
a
good example.
http://spitfiresite.com/2010/04/the-...in-engine.html
"Only 175 had been built and these were considered to be rather
unreliable. As a result, Rolls-Royce introduced an ambitious
reliability-improvement programme to fix the problems. This
consisted
of taking random engines from the end of assembly line and running
them continuously at full power until they failed. Each was then
dismantled to find out which part had failed, and that part was
redesigned to be stronger. After two years of this programme the
Merlin had matured into one of the most reliable aero engines in the
world, and could sustain eight-hour combat missions with no
problems."

In the early decades of the last century, that's how Rolls-Royce
developed their automobile engines, too.

Royce took measurements from the best engines of the day and then
averaged them. That's how he arrived at, for example, the odd
bore/stroke dimensions of their early engines.

The 1904 Grey Ghost was developed that way. To this day, many
historical automobile experts consider it to be the best engine for
its day, of all time.

The bar was rather low in 1904, however. d8-)

--
Ed Huntress

https://www.wired.com/2010/03/boeing...ing-flex-test/

-jsw


Wow! But will it fly?...

If you looked at that without knowing what's going on, you'd think
that Boeing was building an ornithopter -- a wing-flapping airplane.

--
Ed Huntress

Holes in welded and galvanised structures
 

Am Montag, 9. Oktober 2017 15:15:55 UTC+2 schrieb Larry Jaques:

https://www.flickr.com/photos/138493...posted-public/
https://www.flickr.com/photos/138493...posted-public/

Fascinating that the part has 3 weld tails and no (visible) welding on
the bottom left side. Those tabs are under extremely high pressure as
pivot points. Historical failure surely led to this practice. I'll
bet Caterpillar, Kubota, Case, Hitachi, Komatsu, Volvo, etc. engineers
have some stories to tell about them. If you write to them and they
respond, please share it with us. I always got Gibbs-slapped as a kid
because I constantly asked for more details about everything.

Those are JCB loader pivots. Interesting thing is, the early pivot plates did not use this arrangement of welds (instead they were welded all the way around and had no central hole) and they did not regularly fail. However, the early pivot plates were about twice as big and heavy. I figure it's an optimisation process which demands this kind of weld design.

Might write to them if I have time. Not sure that will happen though. The JCB Facebook group would be quicker for an informal answer.

Best wishes,

Chris

Holes in welded and galvanised structures
 

Am Montag, 9. Oktober 2017 15:15:55 UTC+2 schrieb Larry Jaques:

Fascinating that the part has 3 weld tails and no (visible) welding on
the bottom left side. Those tabs are under extremely high pressure as
pivot points. Historical failure surely led to this practice. I'll
bet Caterpillar, Kubota, Case, Hitachi, Komatsu, Volvo, etc. engineers
have some stories to tell about them. If you write to them and they
respond, please share it with us. I always got Gibbs-slapped as a kid
because I constantly asked for more details about everything.

Looks like Volvo does exactly the same thing:
https://www.flickr.com/photos/138493...posted-public/