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Interesting Article On Lead Pipe Corrosion


passion_chorale
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========================

 

I shall have to consult my brother about this.....he's a leading metalurgist.

 

I wonder where the acetic acid is coming from?

 

:blink:

 

MM

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No sooner had I written this, than I thought about the one phenomenon which has changed more than any other in the past 20 years: the high level of microwave pollution all around us.

 

I wonder if the electrolytic process is somehow excited by this background level of radiation?

 

Just a thought!

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No sooner had I written this, than I thought about the one phenomenon which has changed more than any other in the past 20 years: the high level of microwave pollution all around us.

 

I wonder if the electrolytic process is somehow excited by this background level of radiation?

 

Just a thought!

 

So we’d better all turn off our mobile phones in church rather than put them to silent?

 

:blink::P

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So we’d better all turn off our mobile phones in church rather than put them to silent?

 

:blink::P

 

Hi

 

That's not a bad idea anyway - and the same applies in hospitals. The signal generated by a mobile as it logs on to the network every few minutes can interfere with electronic systems - and most church sound systems don't use components of the highest quality anyway!

 

The symptons are usually a series of "clicks" every few minutes.

 

Every Blessing

 

Tony

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No sooner had I written this, than I thought about the one phenomenon which has changed more than any other in the past 20 years: the high level of microwave pollution all around us.

 

I wonder if the electrolytic process is somehow excited by this background level of radiation?

 

Just a thought!

 

 

===========================

 

It was possibly a silly thought, because I rememebered something I read about this earlier in the year.

 

The interesting bit is the presence of acetic-acid, which means that the corrosion of lead pipes is chemical-corrosion rather than electrolytic-corrosion (rust); acetic acid being very bad for lead.

 

I dug around a bit in my files and came up with the following:-

 

http://www.dt.navy.mil/cnsm/lead_02.html

 

Lead is an ancient material and has been used by man for many centuries. Many examples of antiquarian coins, underground pipes, lead roofs on medieval churches, lead coffins, and lead bullets from American Civil War battlefields attest that lead can be nearly eternal.(4) But why does lead sometimes turn to formless powder on our ship models?

 

Organic compounds are the chief category of substances acting harshly upon lead, and Acetic acid is among the most destructive of these carbon compounds. Acetic acid acts upon lead and transforms it into lead carbonate which is the white, granular, powder we frequently see on lead ship model fittings. The museum objects conservation community has been aware of the phenomenon for several decades and the chemical process that causes it is well-understood.(5)

 

The chemical process is: Acetic and some other acids, in the presence of carbon dioxide, catalyze with lead to produce lead acetate and lead hydroxide. Lead acetate and lead hydroxide together react with carbon dioxide and form lead carbonate. Lead carbonate then releases acetic acid and the process becomes self-sustaining.(6) It is important to recognize that the formed lead carbonate is not just a substance clinging to the surface of a casting, it is the surface of the casting transformed to powder. For practical purposes, a portion of the lead is gone and lead carbonate is left in its place. The lead carbonate releases acetic acid which can continue the process until the lead part is progressively consumed from the outside, inward.

 

Acetic acid attacks not only lead, but to a lesser degree, zinc, aluminum, magnesium, brass, copper, nickel, and even steel.(7)

 

-o-o-o-o-o-o-o-o-o-o-o-o-

 

From the same source comes the following:-

 

By the 1890s, museums were noticing that some objects became corroded when stored for long periods of time in wooden drawers. In the 1960s, concerted scientific tests were conducted by museum professionals who specialize in the preservation of historic artifacts.(11) They found that all types of wood release acetic acid and that certain woods emit more than others. End grain releases more than edge grain. Some of the acid is naturally released by the wood and some is released as a function of age as the wood decomposes. In a few cases, seasoned or kiln-dried woods emit more acid than the same wood unseasoned. A secondary lead-corroding product, formic acid, is also produced by wood, but in quantities only about one-tenth as great as acetic acid

 

-o-o-o-o-o-o-o-o-o-o-o-o-o-o-

 

All woods will emit acetic acid to some measurable amount, but the following woods sometimes used by modelers are known to be harmful to lead:(13)

 

Very Harmful

 

Unseasoned oak (white and red)

Plywood and chipboard

Teak

Basswood Sweet chestnut

Fire-proofed woods

Rot-proofed woods

Moderately Harmful

 

Seasoned oak

Larch

Ash Birch

Beech

Red cedar

Less Harmful

 

Sitka spruce

Douglas fir

Pine

Honduras and African mahogany Elm

Ramin

Obeche

 

Woods listed above have been tested by scientists primarily because they are occasionally used in the construction of museum display cases, shipping crates, or storage units. Ship model builders employ many more types of woods than those tested. Nevertheless, a general rule of thumb can be applied: Hardwoods emit more acetic acid than soft woods. But any wood will fall into at least the minimally harmful category

 

-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-

 

The important question is WHY NOW?

 

Why SUDDENLY has it become a problem, after centuries of stability?

 

This is the question of the moment, it would seem.

 

MM

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Of all the possible things to do during Christmas Day lunch (I managed to avoid the bacon & egg scenario), I suppose that a discussion of corrosion in old organ-pipes is one of the least likely topics.

 

However, my brother and myself did exactly this, which must have been quite thrilling for his wife and daughter!

 

Of course, I was soon out of my depth, but my brother being what he is, he rambled on for a good hour!

 

From this virtual monologue, I was able to gleen (decipher?) certain very interesting facts about lead: more importantly; about old lead. The first gem was to discover that ALL corrosion is electrolytic, and this also applies to chemical corrosion in the saltation process, which seems to be what the subject is about.

 

I was also interested to learn that raw, unrefined lead, contains a large number of impurities; ranging from tin, antimony, trace elements of gold and silver to arsenic. Old lead would naturally contain more impurities than lead smelted and refined today under very exacting conditions.

 

My brother was interested by the presence of acetic acid in wood, and the threat this posed to lead, but decided that this was possibly something of a diversion from the primary cause of corrosion in modern times.

He felt that the key to the problem was one of humidity; or rather, an increase in overall humidity. The fact that there would be some boundary-layer reaction between the impurities within the lead, and also between the solder (with high tin content) used to stitch the pipes together, was regarded as relevant, but not to any great extent, considering the fact that the organ-pipes have lasted for so long without major trauma during the preceding three centuries.

 

Humidity seems to be the key, which is obvious enough, because old Lancia motor-cars are still to be found in Italy and Spain, long after their imported UK counterparts disintegrated into unattarctive piles of rust.

 

Why humidity all of a sudden?

 

The question I asked of my brother, betwixt dead turkey and Christmas pudding, was, "Are you saying the world is a wetter place than it was?"

 

His response was fascinating, for he seemed to think that it is not so much absolute humidity which is the critical factor, but actually, less demarcation between day and nightime temperatures due to the general level of global-warming: the one factor which has substantially changed during the past 20-30 years across Europe.

 

At this point I got more interested.

 

We tend to think crudely about drying things out. Put a kettle on, and the water evaporates; thus suggesting that heat is the only thing required. Not a bit of it!

 

It seems obvious enough now, but my brother pointed out that vegetables in a freezer cabinet will dry out if left there long enough. (We've all discovered rock-hard, shrivelled peas at the bottom of the freezer).

 

I will refrain from getting involved with dew-points and condensation, as well as the drying/cooling effects of fluid vapourisation, lest anyone think of me as a scientist. However, temperature and humidity are very closely linked, so it seems, and a warmer body capable of absorbing moisture, will have higher saturation at higher temperatures, and lower saturation at lower temperatures. Consequently, the colder a climate, the more condensation occurs, and the more the water-vapour (now in condensed form) is removed when the air-temperature rises again.

 

In a nutshell, if there is less in the way of temperature change between night and day, or between summer and winter, the more moist things will get as overall temperatures rise (even by small amounts), until a new level of saturation is achieved.

 

This didn't answer the critical question, as to whether the increase in saturation was allowing acetic-acid to creep out of wood in the form of gas and condensed fluid, or whether the moisture was causing an electrolytic reaction between the various impurities at the boundary-layers of the pipe-metal. (The boundary-layer being the point at which metal meets air), or whether some other corrosion process was involved at the deeper, crystalline layers.

 

We were now on mince-pies and fresh coffee, and everyone had glazed eyes.

 

So there we have it!

 

If my brother had simply said, "Things are staying damper for longer, due to climate change," we could all have enjoyed "Harry Potter and the Philosopher's Stone" instead.....but he's a scientist.

 

As a final thought, I asked my brother whether there may be a remedy to the problem.

 

"Oh yes.....spray the pipes with ACF-50. That's what I do to my motorbike!"

 

(ACF-50 was developed for the aero industry, and is apparently quite wonderful at preventing corrosion).

 

However, the one statement which rocked me on my heels, was when my cousin and my brother recalled a conversation they had with the late Prof.Sir Fred Hoyle.

 

Apparently, Hoyle said this:-

 

"The planet Earth warms and cools quite naturally, in cycles, because it is self-regulating"

 

THAT CONVERSATION TOOK PLACE 40 YEARS AGO!!!!!!!!

 

(Another memorable quote from Hoyle, which I like a lot, is, "If your car could go vertically, it's only a couple of hours drive into space.")

 

MM

 

 

 

 

PS:

 

Oops! I almost forgot to include a thought.

 

Organ-builders have for years installed humidifiers, but perhaps what is now required are humidity stabilisers, which not only put moisture in, but also take moisture out.

 

Would that solve the problem, I wonder?

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The corrosion topic is interesting, because I occasionally have cause to strip organ pipes of their paint. To do this, they go off to the local door stripping chappy who dips them in a tank of industrial Nitromors then hoses them off. I know of others who have been doing this for donkey's years, and it brings them up superbly, including original and long-obscured markings. I have suggested this to a couple of people who have needed to get rid of some bat poo - virtually impossible to shift. Surely if acid degredation of pipes was THAT much of a problem, then dipping them in a vat of acid for several hours would cause instant and lasting damage??? Even the solder comes out looking like new!

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The corrosion topic is interesting, because I occasionally have cause to strip organ pipes of their paint. To do this, they go off to the local door stripping chappy who dips them in a tank of industrial Nitromors then hoses them off. I know of others who have been doing this for donkey's years, and it brings them up superbly, including original and long-obscured markings. I have suggested this to a couple of people who have needed to get rid of some bat poo - virtually impossible to shift. Surely if acid degredation of pipes was THAT much of a problem, then dipping them in a vat of acid for several hours would cause instant and lasting damage??? Even the solder comes out looking like new!

 

 

================================

 

 

I don't think acid is used for any paint or varnish-stripping purposes. Caustic Soda is about as strong as it gets in the stripping of old pine furniture.

 

'Nitromors' (trade name) is actually based on methylene chloride (dichloromethane), a heavy chlorohydrocarbon; chemical symbol CH2Cl2. A derivative product name is 'Freon'....the stuff used in air-conditioning systems, which if breathed in quantity, causes asphyxiation and heart-attacks as a result. Nasty stuff, but effective, and something of a known carcinogen.

 

I came across the following concerning the effects of acetic-acid on Lead, which makes interesting reading:-

 

Department of Environmental Inorganic Chemistry, Chalmers University of Technology, SE-412 96 Göteborg, Sweden

(Revised 16 June 2005; published 18 October 2005)

 

The present study investigates the influence of low concentrations of acetic acid vapor on the atmospheric corrosion of lead. The samples were exposed to synthetic air with careful control of relative humidity (95%), temperature (22.00°C), acetic acid concentration (170–1100 ppb), CO2 concentration (350 ppm), and flow conditions. The exposure times were between 1 and 4 weeks. Mass gain results are reported. The corrosion products were analyzed by ion chromatography, quantitative carbonate analysis, and X-ray diffraction. The surface morphology of the exposed samples was investigated with environmental scanning electron microscope. The results show that low concentrations of acetic acid vapor are very corrosive toward lead. The mass gain is linear with time and depends linearly on the acetic acid concentration. It is suggested that the corrosion of lead in the presence of traces of acetic acid vapor is electrochemical in nature. The corrosion products found were plumbonacrite, Pb10O(OH)6(CO3)6, lead acetate oxide hydrate (Pb(CH3COO)2·2PbO·H2O), and lead oxide, PbO.

 

----------------------------------------

 

 

Apparently, the morphology of the lead is critical to the rate of corrosion, which is what my brother was yarking on about when he spoke of the impurities in old lead.

 

As I am informed that acetic-acid and acetates could not come from within the metal, and as the stuff isn't exactly floating around the atmosphere in great quantity, it would seem that the slight gaseous outflow from dampened wood is the most likely source, because acetic-acid can be generated by the slow fermentation process.

 

I suspect that it amounts to simple damp, which is not drying out for the reasons elaborated upon in the previous post.

 

MM

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  • 2 weeks later...

Further to my recent post about lead corrosion and the anti-corrosion treatment ACF-50, I wrote to the manufacturers of the fluid to ask their advice on the possible suitability of the inhibitor in pipe-organs.

 

I shall not comment upon their reply, but it was of great interest to me: especially the comment about wood preservation.

 

Here is the reply:-

 

Hello Colin,

 

Thank you for the inquiry and for your interest in ACF-50.

 

The short answer is we have no data to offer on ACF-50's effect on leather/sheep skin components...especially ones as aged as the ones you describe. Our only suggestion is to try a small amount of ACF-50 on a sample to ascertain any negative effects.

 

ACF-50 has been used for over twenty years now to protect the metallic components found within wooden ribbed aircraft with no deleterious effects ever reported. ACF-50's capillary action coupled with its hydrophobic characteristics may act a a wood preservative....although again we have no direct data to support that claim.

 

It will work well to protect the lead pipes.

 

I'm sorry we could'nt be more helpful.

 

Mark Pearson, Managing Director

Lear Chemical Research Corp

 

===========================

 

 

Now, if Mr Mander would like to just try a little bit on a piece of sheepskin, and let us know if it bursts into flames, contorts into a glove or withers away to a pile of dust, then perhaps we may have made a significant contribution to the protection of old organs.

 

MM

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Now, if Mr Mander would like to just try a little bit on a piece of sheepskin, and let us know if it bursts into flames, contorts into a glove or withers away to a pile of dust, then perhaps we may have made a significant contribution to the protection of old organs.

 

MM

How long would Mr Mander have to wait and under what conditions should he store the said piece of sheepskip before coming to a conclusion?

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How long would Mr Mander have to wait and under what conditions should he store the said piece of sheepskip before coming to a conclusion?

 

 

==============================

 

The short answer is that I have absolutely no idea.

 

What I do know is that the anti-corrosion fluid in question does not leave a waxy residue, and doesn't harden like some barrier-coatings.

 

The reason I wonder about leather, is simply that the capillary-action (creep) of the fluid is such, that it will get almost anywehre, and that may mean that it creeps into contact with leather via footholes etc.

 

The problem seems to be that no-one actually knows what is in ACF-50, but work is certainly does in quite tough environments.

 

The point that I failed to mention about lead-corrosion, is the fact that once the corrosion reaction in lead begins, it soon accelerates and is self-perpetuating. I suspect that anything which "buys time," if it safe, could be worth its weight in gold.

 

 

MM

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