What could have caused the heating pipe to corrode so badly that it failed? It was next to an external wall and lagged. The are a couple of lengths of the pipe lying outside the building unused for the same 6 years, other than the threaded ends, they look new.
image https://drive.google.com/open?id=1o8...cqBdRGYatmQb6R

On Mon, 11 Mar 2019 10:37:31 -0700 (PDT)
misterroy wrote:

What could have caused the heating pipe to corrode so badly that it
failed? It was next to an external wall and lagged. The are a couple
of lengths of the pipe lying outside the building unused for the same
6 years, other than the threaded ends, they look new. image
https://drive.google.com/open?id=1o8...cqBdRGYatmQb6R

Accumulation of moisture inside the lagging plus warmth from lagging
equals accelerated oxidation?

"misterroy" wrote in message
...
What could have caused the heating pipe to corrode so badly that it
failed? It was next to an external wall and lagged. The are a couple of
lengths of the pipe lying outside the building unused for the same 6
years, other than the threaded ends, they look new.
image https://drive.google.com/open?id=1o8...cqBdRGYatmQb6R

Most likely significant electrolysis due to a ****ed mains earth system and
bonding.

On 11/03/2019 17:37, misterroy wrote:
What could have caused the heating pipe to corrode so badly that it failed? It was next to an external wall and lagged. The are a couple of lengths of the pipe lying outside the building unused for the same 6 years, other than the threaded ends, they look new.
image https://drive.google.com/open?id=1o8...cqBdRGYatmQb6R

Do you, by any chance, have an electro-osmotic damp proof course fitted?

I have had two instances of *earthed* components in contact with damp
masonry corroding in a similarly dramatic fashion. One was a galvanised
back-box (which I replaced by setting-in a plastic one), the other was
the screws and after that four six inch lengths of 316 stainless steel
6mm studding which I set into the rubble stone wall to support radiator
brackets.

I havn't had any trouble with other galvanised back boxes, but this one
was in a bit of wall which the DPC was spectacularly failing to protect.

However given the distribution of corrosion in your case I would be more
inclined to associate it with condensation within the insulation,
especially in the presence of salts.

water and air usually or maybe the plating was naff?
Brian

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"misterroy" wrote in message
...
What could have caused the heating pipe to corrode so badly that it failed?
It was next to an external wall and lagged. The are a couple of lengths of
the pipe lying outside the building unused for the same 6 years, other than
the threaded ends, they look new.
image https://drive.google.com/open?id=1o8...cqBdRGYatmQb6R

On 11/03/2019 21:20, Brian Gaff wrote:
water and air usually or maybe the plating was naff?
Brian


It is actually quite surprising how slowly iron corrodes under normal
but adverse conditions. The upper bound on metal loss rate is usually
assumed to be 0.1 mm / year even in marine environments. You can get
*pitting* at much greater rates than this, which is why car bodywork was
so dreadful a few decades ago before manufacturers bothered properly.

But 0.1 mm/year explains why Victorian Piers and lock gate mechanisms
are still there, even without repainting.

newshound Wrote in message:
On 11/03/2019 21:20, Brian Gaff wrote:
water and air usually or maybe the plating was naff?
Brian


It is actually quite surprising how slowly iron corrodes under normal
but adverse conditions. The upper bound on metal loss rate is usually
assumed to be 0.1 mm / year even in marine environments. You can get
*pitting* at much greater rates than this, which is why car bodywork was
so dreadful a few decades ago before manufacturers bothered properly.

But 0.1 mm/year explains why Victorian Piers and lock gate mechanisms
are still there, even without repainting.


They weren't made of galvanised steel though were they?
--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

On Monday, March 11, 2019 at 8:33:38 PM UTC, newshound wrote:
On 11/03/2019 17:37, misterroy wrote:
What could have caused the heating pipe to corrode so badly that it failed? It was next to an external wall and lagged. The are a couple of lengths of the pipe lying outside the building unused for the same 6 years, other than the threaded ends, they look new.
image https://drive.google.com/open?id=1o8...cqBdRGYatmQb6R

Do you, by any chance, have an electro-osmotic damp proof course fitted?

I have had two instances of *earthed* components in contact with damp
masonry corroding in a similarly dramatic fashion. One was a galvanised
back-box (which I replaced by setting-in a plastic one), the other was
the screws and after that four six inch lengths of 316 stainless steel
6mm studding which I set into the rubble stone wall to support radiator
brackets.

I havn't had any trouble with other galvanised back boxes, but this one
was in a bit of wall which the DPC was spectacularly failing to protect.

However given the distribution of corrosion in your case I would be more
inclined to associate it with condensation within the insulation,
especially in the presence of salts.

Does the earthing cancel out the benefit of galvanising the steel, giving the electrons somewhere else to go?

On Monday, 11 March 2019 17:37:33 UTC, misterroy wrote:
What could have caused the heating pipe to corrode so badly that it failed? It was next to an external wall and lagged. The are a couple of lengths of the pipe lying outside the building unused for the same 6 years, other than the threaded ends, they look new.
image https://drive.google.com/open?id=1o8...cqBdRGYatmQb6R

If it is attached to copper pipe elsewhere in the system, zinc and copper are perfect for galvanic action.
Depends too on the quality of the water in the system. Inhibitors are available.

On 12/03/2019 06:47, misterroy wrote:
On Monday, March 11, 2019 at 8:33:38 PM UTC, newshound wrote:
On 11/03/2019 17:37, misterroy wrote:
What could have caused the heating pipe to corrode so badly that it failed? It was next to an external wall and lagged. The are a couple of lengths of the pipe lying outside the building unused for the same 6 years, other than the threaded ends, they look new.
image https://drive.google.com/open?id=1o8...cqBdRGYatmQb6R

Do you, by any chance, have an electro-osmotic damp proof course fitted?

I have had two instances of *earthed* components in contact with damp
masonry corroding in a similarly dramatic fashion. One was a galvanised
back-box (which I replaced by setting-in a plastic one), the other was
the screws and after that four six inch lengths of 316 stainless steel
6mm studding which I set into the rubble stone wall to support radiator
brackets.

I havn't had any trouble with other galvanised back boxes, but this one
was in a bit of wall which the DPC was spectacularly failing to protect.

However given the distribution of corrosion in your case I would be more
inclined to associate it with condensation within the insulation,
especially in the presence of salts.

Does the earthing cancel out the benefit of galvanising the steel, giving the electrons somewhere else to go?

I was going to say no, that earthing is necessary to close the circuit.
Making the DPC conductor positive steals electrons from the piece of
metal, turning them into ions which are then mobile instead of being
part of the structure. But on reflection I think you are saying the same
thing.

It's electroplating in reverse. Similar to the way that sacrificial
anodes are used to prevent corrosion of marine hulls, etc.

On 12/03/2019 00:04, Jim K.. wrote:
newshound Wrote in message:
On 11/03/2019 21:20, Brian Gaff wrote:
water and air usually or maybe the plating was naff?
Brian


It is actually quite surprising how slowly iron corrodes under normal
but adverse conditions. The upper bound on metal loss rate is usually
assumed to be 0.1 mm / year even in marine environments. You can get
*pitting* at much greater rates than this, which is why car bodywork was
so dreadful a few decades ago before manufacturers bothered properly.

But 0.1 mm/year explains why Victorian Piers and lock gate mechanisms
are still there, even without repainting.


They weren't made of galvanised steel though were they?

No, galvanising allows even thinner sections (corrugated iron, for
example) to survive for decades.

newshound Wrote in message:
On 12/03/2019 00:04, Jim K.. wrote:
newshound Wrote in message:
On 11/03/2019 21:20, Brian Gaff wrote:
water and air usually or maybe the plating was naff?
Brian


It is actually quite surprising how slowly iron corrodes under normal
but adverse conditions. The upper bound on metal loss rate is usually
assumed to be 0.1 mm / year even in marine environments. You can get
*pitting* at much greater rates than this, which is why car bodywork was
so dreadful a few decades ago before manufacturers bothered properly.

But 0.1 mm/year explains why Victorian Piers and lock gate mechanisms
are still there, even without repainting.


They weren't made of galvanised steel though were they?

No, galvanising allows even thinner sections (corrugated iron, for
example) to survive for decades.


And Victorian piers & lock gates are probably cast iron not steel?
--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

On Tuesday, 12 March 2019 07:41:21 UTC, harry wrote:
On Monday, 11 March 2019 17:37:33 UTC, misterroy wrote:
What could have caused the heating pipe to corrode so badly that it failed? It was next to an external wall and lagged. The are a couple of lengths of the pipe lying outside the building unused for the same 6 years, other than the threaded ends, they look new.
image https://drive.google.com/open?id=1o8...cqBdRGYatmQb6R

If it is attached to copper pipe elsewhere in the system, zinc and copper are perfect for galvanic action.
Depends too on the quality of the water in the system. Inhibitors are available.

Is there some way to stop this corrosion in a CH system using copper pipes & a galvanised steel cylinder/tank?


NT

Wrote in message:
On Tuesday, 12 March 2019 07:41:21 UTC, harry wrote:
On Monday, 11 March 2019 17:37:33 UTC, misterroy wrote:
What could have caused the heating pipe to corrode so badly that it failed? It was next to an external wall and lagged. The are a couple of lengths of the pipe lying outside the building unused for the same 6 years, other than the threaded ends, they look new.
image https://drive.google.com/open?id=1o8...cqBdRGYatmQb6R

If it is attached to copper pipe elsewhere in the system, zinc and copper are perfect for galvanic action.
Depends too on the quality of the water in the system. Inhibitors are available.

Is there some way to stop this corrosion in a CH system using copper pipes & a galvanised steel cylinder/tank?


NT


Inhibitor?
--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

On Tuesday, 12 March 2019 18:52:04 UTC, wrote:
On Tuesday, 12 March 2019 07:41:21 UTC, harry wrote:
On Monday, 11 March 2019 17:37:33 UTC, misterroy wrote:
What could have caused the heating pipe to corrode so badly that it failed? It was next to an external wall and lagged. The are a couple of lengths of the pipe lying outside the building unused for the same 6 years, other than the threaded ends, they look new.
image https://drive.google.com/open?id=1o8...cqBdRGYatmQb6R

If it is attached to copper pipe elsewhere in the system, zinc and copper are perfect for galvanic action.
Depends too on the quality of the water in the system. Inhibitors are available.

Is there some way to stop this corrosion in a CH system using copper pipes & a galvanised steel cylinder/tank?


NT

The reason why galv water tanks rusted was the copper pipes they were attached to.
Now we have plastic tanks.

Generally, any inhibitor in the system won't be in the header tank, just in the pipework.
Obviously, a problem if it's a galv.steel tank.

But it protects steel radiators in a copper pipe system. (Somewhat) Another reason to use plastic pipe instead of copper.

On Tuesday, 12 March 2019 18:52:04 UTC, wrote:
On Tuesday, 12 March 2019 07:41:21 UTC, harry wrote:
On Monday, 11 March 2019 17:37:33 UTC, misterroy wrote:
What could have caused the heating pipe to corrode so badly that it failed? It was next to an external wall and lagged. The are a couple of lengths of the pipe lying outside the building unused for the same 6 years, other than the threaded ends, they look new.
image https://drive.google.com/open?id=1o8...cqBdRGYatmQb6R

If it is attached to copper pipe elsewhere in the system, zinc and copper are perfect for galvanic action.
Depends too on the quality of the water in the system. Inhibitors are available.

Is there some way to stop this corrosion in a CH system using copper pipes & a galvanised steel cylinder/tank?


NT

The way galv tanks are protected is with a magnesium "sacrificial anode"
Has to be replaced every few years as it "rots" away instead of the tank.

https://en.wikipedia.org/wiki/Cathodic_protection

http://www.waterheaterrescue.com/Lon...er-anodes.html

In article , harry
wrote:
On Tuesday, 12 March 2019 18:52:04 UTC, wrote:
On Tuesday, 12 March 2019 07:41:21 UTC, harry wrote:
On Monday, 11 March 2019 17:37:33 UTC, misterroy wrote:
What could have caused the heating pipe to corrode so badly that it
failed? It was next to an external wall and lagged. The are a
couple of lengths of the pipe lying outside the building unused for
the same 6 years, other than the threaded ends, they look new.
image
https://drive.google.com/open?id=1o8...cqBdRGYatmQb6R

If it is attached to copper pipe elsewhere in the system, zinc and
copper are perfect for galvanic action. Depends too on the quality of
the water in the system. Inhibitors are available.

Is there some way to stop this corrosion in a CH system using copper
pipes & a galvanised steel cylinder/tank?


NT

The reason why galv water tanks rusted was the copper pipes they were
attached to. Now we have plastic tanks.

Generally, any inhibitor in the system won't be in the header tank, just
in the pipework. Obviously, a problem if it's a galv.steel tank.

You normally pour the inhibitor into the header tank from where it
circulates round the system.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On Wednesday, 13 March 2019 10:26:56 UTC, charles wrote:
In article , harry
wrote:
On Tuesday, 12 March 2019 18:52:04 UTC, wrote:
On Tuesday, 12 March 2019 07:41:21 UTC, harry wrote:
On Monday, 11 March 2019 17:37:33 UTC, misterroy wrote:
What could have caused the heating pipe to corrode so badly that it
failed? It was next to an external wall and lagged. The are a
couple of lengths of the pipe lying outside the building unused for
the same 6 years, other than the threaded ends, they look new.
image
https://drive.google.com/open?id=1o8...cqBdRGYatmQb6R

If it is attached to copper pipe elsewhere in the system, zinc and
copper are perfect for galvanic action. Depends too on the quality of
the water in the system. Inhibitors are available.

Is there some way to stop this corrosion in a CH system using copper
pipes & a galvanised steel cylinder/tank?


NT

The reason why galv water tanks rusted was the copper pipes they were
attached to. Now we have plastic tanks.

Generally, any inhibitor in the system won't be in the header tank, just
in the pipework. Obviously, a problem if it's a galv.steel tank.

You normally pour the inhibitor into the header tank from where it
circulates round the system.

You won't get much in the system if you do that.
The system has to be partially drained and then the inhibitor added to get in in the pipework/radiators.

On 13/03/2019 10:25, charles wrote:
You normally pour the inhibitor into the header tank from where it
circulates round the system.

Or if no header tank, the highest rad after you have de pressurised the
system a bit and let some air in.


--
€œSome people like to travel by train because it combines the slowness of
a car with the cramped public exposure of €¨an airplane.€�

Dennis Miller

In article , harry
wrote:
On Wednesday, 13 March 2019 10:26:56 UTC, charles wrote:
In article ,
harry wrote:
On Tuesday, 12 March 2019 18:52:04 UTC, wrote:
On Tuesday, 12 March 2019 07:41:21 UTC, harry wrote:
On Monday, 11 March 2019 17:37:33 UTC, misterroy wrote:
What could have caused the heating pipe to corrode so badly
that it failed? It was next to an external wall and lagged. The
are a couple of lengths of the pipe lying outside the building
unused for the same 6 years, other than the threaded ends, they
look new. image
https://drive.google.com/open?id=1o8...cqBdRGYatmQb6R

If it is attached to copper pipe elsewhere in the system, zinc
and copper are perfect for galvanic action. Depends too on the
quality of the water in the system. Inhibitors are available.

Is there some way to stop this corrosion in a CH system using
copper pipes & a galvanised steel cylinder/tank?


NT

The reason why galv water tanks rusted was the copper pipes they were
attached to. Now we have plastic tanks.

Generally, any inhibitor in the system won't be in the header tank,
just in the pipework. Obviously, a problem if it's a galv.steel tank.

You normally pour the inhibitor into the header tank from where it
circulates round the system.

You won't get much in the system if you do that. The system has to be
partially drained and then the inhibitor added to get in in the
pipework/radiators.

That goes without saying. and you will stll have some inhibitot in the
header tank

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On Wednesday, 13 March 2019 08:08:49 UTC, harry wrote:
On Tuesday, 12 March 2019 18:52:04 UTC, tabby wrote:
On Tuesday, 12 March 2019 07:41:21 UTC, harry wrote:
On Monday, 11 March 2019 17:37:33 UTC, misterroy wrote:
What could have caused the heating pipe to corrode so badly that it failed? It was next to an external wall and lagged. The are a couple of lengths of the pipe lying outside the building unused for the same 6 years, other than the threaded ends, they look new.
image https://drive.google.com/open?id=1o8...cqBdRGYatmQb6R

If it is attached to copper pipe elsewhere in the system, zinc and copper are perfect for galvanic action.
Depends too on the quality of the water in the system. Inhibitors are available.

Is there some way to stop this corrosion in a CH system using copper pipes & a galvanised steel cylinder/tank?


NT

The way galv tanks are protected is with a magnesium "sacrificial anode"
Has to be replaced every few years as it "rots" away instead of the tank.

https://en.wikipedia.org/wiki/Cathodic_protection

http://www.waterheaterrescue.com/Lon...er-anodes.html

thanks, useful. Galv tanks are so much cheaper than copper.


NT

On 12/03/2019 18:15, Jim K.. wrote:
newshound Wrote in message:
On 12/03/2019 00:04, Jim K.. wrote:
newshound Wrote in message:
On 11/03/2019 21:20, Brian Gaff wrote:
water and air usually or maybe the plating was naff?
Brian


It is actually quite surprising how slowly iron corrodes under normal
but adverse conditions. The upper bound on metal loss rate is usually
assumed to be 0.1 mm / year even in marine environments. You can get
*pitting* at much greater rates than this, which is why car bodywork was
so dreadful a few decades ago before manufacturers bothered properly.

But 0.1 mm/year explains why Victorian Piers and lock gate mechanisms
are still there, even without repainting.


They weren't made of galvanised steel though were they?

No, galvanising allows even thinner sections (corrugated iron, for
example) to survive for decades.


And Victorian piers & lock gates are probably cast iron not steel?

Cast iron and "ordinary" steels (like anchor chain, for example) have
very similar corrosion rates in marine environments.

On Tue, 12 Mar 2019 07:32:07 +1100, Jac Brown, better known as cantankerous
trolling senile geezer Rot Speed, wrote:


Most likely significant electrolysis due to a ****ed mains earth system and
bonding.

No mains earth system could ever be as ****ed as your senile head, senile
Rot!

--
Bod addressing abnormal senile quarreller Rot:
"Do you practice arguing with yourself in an empty room?"
MID:

On Wednesday, 13 March 2019 12:59:32 UTC, wrote:
On Wednesday, 13 March 2019 08:08:49 UTC, harry wrote:
On Tuesday, 12 March 2019 18:52:04 UTC, tabby wrote:
On Tuesday, 12 March 2019 07:41:21 UTC, harry wrote:
On Monday, 11 March 2019 17:37:33 UTC, misterroy wrote:
What could have caused the heating pipe to corrode so badly that it failed? It was next to an external wall and lagged. The are a couple of lengths of the pipe lying outside the building unused for the same 6 years, other than the threaded ends, they look new.
image https://drive.google.com/open?id=1o8...cqBdRGYatmQb6R

If it is attached to copper pipe elsewhere in the system, zinc and copper are perfect for galvanic action.
Depends too on the quality of the water in the system. Inhibitors are available.

Is there some way to stop this corrosion in a CH system using copper pipes & a galvanised steel cylinder/tank?


NT

The way galv tanks are protected is with a magnesium "sacrificial anode"
Has to be replaced every few years as it "rots" away instead of the tank.

https://en.wikipedia.org/wiki/Cathodic_protection

http://www.waterheaterrescue.com/Lon...er-anodes.html

thanks, useful. Galv tanks are so much cheaper than copper.


NT

There's the cost of the sacrificial anode replacements to consider too.