# Water Gauges for Boilers.



## Tony Bird (Oct 27, 2013)

Hi,

Some Thoughts on the Design & Construction of a Small Water Gauge suitable for Model Steam Boilers.

I have made many small steam boilers and usually make the fittings for them as well. Boiler fittings usually look better if they are small, there is a limit to how small of course, they have to work. Designing and making boiler water gauges over the years I have decided on several factors that effect how well they work.

Use the largest diameter glass tube you can, I have found that a tube 4mm OD with an ID of 2.5mm is about as small as you can hope to work. Also the minimum size of the water/steam holes in the fittings should be the same size or larger than the ID of the glass tube. Another factor to be considered is the ease of cleaning the gauge glass. The glass itself can usually be cleaned by removing the nut on the top fitting and pushing a pipe cleaner (tobacco type pipe) down into the tube. It is also a good idea to be able to clean out any mineral deposits that accumulate in the bottom fitting without having to remove it from the boiler. Good boiler hygiene can reduce this mineral deposit problem even if like me you live in a soft water area and mostly use rainwater in your boilers. If the boiler is used frequently like the one I use for testing models it is a good idea to completely fill the boiler with a mild acid such as citric or white vinegar about once a year. Leave the acid in the boiler for a few hours say over night then after emptying the acid flush well with clean water. Doing this will remove a lot of the deposits that might be in the boiler. If the boiler isnt used much it is a good idea to drain the water from it after use.

With small boilers it is often difficult to make the water gauge short enough so there is enough visible length left on the glass tube to see a reasonable length of water usage.

The design following tries to keep the height of the fittings as small as practical and its design is based on previously made gauges. First a couple of photographs of some gauges already made. They are basically of the same type.

One made using round stock for the bodies
.




One made from round stock fitted with a blow down valve.  Note the glass tubes which are half white with various lines running down them are often slightly over size and out of round.  They are also a little more difficult to cut.





One made from hexagonal stock.





The one that the one to be described is based on this one which is made from 7mm square stock which had to be machined specially. Note the screws which allow the holes in the brass bodies to be cleaned






Machining 7mm square stock on a shellac chuck.






The one to be described uses a slightly larger 8mm (5/16) square stock, which is a standard size rod. The extra thickness will allow easier fitting of blow down valves either directly to the fitting or by pipe to a valve, also the overall dimension of the top and bottom fitting will be the same rather than different. Two prototypes will be built from square stock and another two using 8mm (5/16) hexagonal stock to see how they compare.

Drawing of the proposed water gauge which will probably be modified as the parts are made.






Materials to be used brass stock; 8mm (5/16) square for the gauges main body, 8mm (5/16) hexagonal for nuts and prototype main body. 6.35mm (1/4) hexagonal for attaching the gauge to the boiler,





In the next couple of days I will post some photographs taken while machining the parts of the gauges. 



Regards Tony.


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## Tony Bird (Oct 28, 2013)

Hi,

Today I made a start on four prototype water gauges.

First both ends of the 8mm square and hexagonal rods were marked out on both sides for drilling the transverse holes.





The small drilling machine used.





Setting the drill for the depth of the 3.6mm hole.





Drilling the 3.6mm hole part the way through.





Drilling through from opposite side for the 1.8mm hole.





Tapping the 1.8mm hole 8BA.





Drilled holes.





Lathe set up for machining the Water Gauge bodies.





Centre drilling end.





Calibrated tail stock mandrel. A short length of metric ruler has been let into the mandrel.





Drilling a 4.2mm hole 4mm deep. Shows scribed mark for shoulder.





No photograph of drilling the 3mm hole which breaks into the transverse hole.


Checking the glass tube fits and will rest on the internal shoulder. 





Turning a 4.8mm shoulder 3mm deep.






Tapping ¼x 40 ME thread.





Reversed die to finish the thread.





Parting graver and homemadeT rest.





Hand turning thread relief.





Top of thread relieved.





Clearing thread with nut.





Setting parting tool.





Parting off.





Facing end.





One of each hex and square bottom water gauge bodies.





I will probably get a bit more done in the next few days

Regards Tony.


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## tomfilery (Oct 29, 2013)

Tony,

 Lovely work and good explanation - as usual.

 I'll be watching with interest.

Regards Tom


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## RonGinger (Oct 29, 2013)

Very nice.

Please get good photos of how you get the thread deep enough for the nut, like the glass tube


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## SilverSanJuan (Oct 29, 2013)

Very nice, Tony.  Thanks for sharing your techniques with us in a such a finely detailed way. 

Todd


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## chrsbrbnk (Oct 29, 2013)

The  water sight glasses look great  sort of a side note  a lot of the shows require that the bottom of the glass ( just disappearing into the lower nut) be above the crown sheet or above the level where damage occurs to the boiler.   this gets pretty tough as the model gets smaller


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## Tony Bird (Oct 30, 2013)

Hi,

I made a start on the supports for the bodies of the water gauge today.

As with the body of the water gauge the 1/4" hexagonal rod that the bodies supports were to be made from was centre drilled before drilling a 2.6mm hole 10mm deep, then a 3mm long 3.8mm diameter should was turned.





Because I didn't want to take the tools out of the tailstock turret a plain die holder was used to tap the thread.





As before the top of the thread was relieved by hand turning.





To reduce the chances of loosing the work piece when parting off a rod held in by the tailstock was placed in the work piece.





Parted and captured!





Lathe used to shoulder end of body support piece.






Turning Shoulder





Dry assembled.





Solder. When soldering small fittings I like to hammer flat the solder so it can be presented to the joint.





Soldering.













Cleaned up.





For most boiler fittings it isn't very important that they are exactly at right angles to the boiler. However it is important that the bushes fitted for water gauges are, this is how I check and correct them.





A little pull.





Back head of boiler with the two types of bottom water gauge bodies fitted.





Now to make another 6 of the body supports. Then if the '0' rings ordered arrive tomorrow the nuts will be made, if not the top fittings will be started on.

Regards Tony.


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## Tony Bird (Oct 31, 2013)

Hi,

The gauge glass '0' rings that have been ordered have yet to arrive but made a start on the nuts anyway.

Material 8mm (5/16") hexagonal brass rod drilled deep with a 1/4" centre drill.





Drilled 5.5mm, 5mm deep.





Drilled another 3mm with a 4.2mm drill.





End of 5.5mm hole squared with a 5.5mm flat end drill.





Tapped 1/4"x 40TPI.





Thread finished with a flat end tap.





The flat end drill and tap are standard with their ends ground flat.





Shortening internal length of nut to 3mm.





Bevelling edge of nut by hand.





Parting off.





Squaring nut in chuck using tailstock chuck.





Facing to 4mm.





Bevelling by hand, lathe run backwards far side of nut being turned.





Clearing hole with a broach.





Finished fitted on body.





With glass tube fitted.





Sorry about the poor quality of some of the photographs.  Is this what you were referring to Ron?

Regards Tony.


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## RonGinger (Oct 31, 2013)

Yes, thanks. The square end drill and tap are clearly the important part. Is that a regular bottom tap, or have you ground some to make it a full thread right to the bottom?


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## Tony Bird (Nov 1, 2013)

Hi Ron,

*The square end drill and tap are clearly the important part. Is that a regular bottom tap, or have you ground some to make it a full thread right to the bottom? *

Yes, both are standard products which I ground flat though I believe it is possible to buy both.

Regards Tony.


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## Niceonetidy (Nov 1, 2013)

Tony,

Great job. Do yoou know you should be using Bronze for boiler fittings?  Brass suffers from de zincafication, and goes all powdery and can fail with disastrous results.  Please keep in mind,

Regards

Colin


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## Tony Bird (Nov 1, 2013)

Hi Colin,

Yes I know that bronze would be better to use for boiler fittings than brass.  All the boilers I make use bronze bushes and I always blow down the boilers after use, which must reduce the effects of de zincification.  Is it now mandatory in the UK to use bronze for boiler fittings?  Are all the commercially available boiler fittings made from bronze?  It would be good to know.

Regards Tony.


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## nevadablue (Nov 1, 2013)

Tony,
Thanks for taking the time to do this excellent thread. The pictures and information are invaluable to a novice like me. Seeing actual working setups is just great! 
Ken


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## SilverSanJuan (Nov 1, 2013)

nevadablue said:


> Tony,
> Thanks for taking the time to do this excellent thread. The pictures and information are invaluable to a novice like me. Seeing actual working setups is just great!
> Ken



+1 on that.  This has been very helpful for me, Tony.  Thanks for sharing your work. 

Todd


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## Niceonetidy (Nov 1, 2013)

Yes, they are, and most clubs and society's are quite strict when noticing anything that looks too yellow.  I have never heard of a fitting let go when ISPs steam, but have heard of them breaking easily when being removed.

Nice thread,

Kind regards

Colin



UOTE=Tony Bird;235515]Hi Colin,

Yes I know that bronze would be better to use for boiler fittings than brass.  All the boilers I make use bronze bushes and I always blow down the boilers after use, which must reduce the effects of de zincification.  Is it now mandatory in the UK to use bronze for boiler fittings?  Are all the commercially available boiler fittings made from bronze?  It would be good to know.

Regards Tony.[/QUOTE]


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## tomfilery (Nov 1, 2013)

Tony,

 Although the conventional wisdom seems to be that boiler bushes MUST be bronze (and that was the case going back many years), I have, so far, failed to find any indication that it is compulsory to make all external fittings from bronze.  I suspect this is the next big lie we are to be sold (like all boilers must have a boiler certificate).  There is no logical reason for fittings to need to be bronze, as they usually can be replaced - whereas boiler bushes generally can't easily.  

 Obviously, size of loco and operating pressure may dictate different practice to 16mm/ft, but LBSC used to recommend bronze bushes, yet make all his fittings from brass.

 Please continue with your informative thread.

 Regards Tom


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## Tony Bird (Nov 2, 2013)

Hi,

The '0' rings arrived yesterday and thankfully fitted! 











 

Other that cutting some gauge glasses no further work has been done on the water gauges. but now I know the '0' rings fit another seven nuts will be made.









What else I did yesterday might be found interesting and not really worth a separate posting was making a cap for a locomotive chimney. Over the winter I service the GR locomotives and stock of my model club. One of the locomotives had lost the cap off its chimney, following are a couple of photographs of making a replacement.

First some brass was drilled and roughed out using the fixed tools of the lathe then finished using hand tools.


















And fitted to the locomotive.





A bit OTT but Thomas does pull Santa on the GR when we have the model clubs Santa Special open day in a few weeks time.

Back to making nuts.

Regards Tony.


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## Gedeon Spilett (Nov 2, 2013)

Great thread Tony, everything seems so easy while reading it. thanks to share.

By the way, amongst many, a company such as Regner uses brass for steam fittings, for bushes and even for boilers !
I would be very surprised if a club or a society refuses such high quality products during a show...


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## Tony Bird (Nov 4, 2013)

Hi,

All the nuts and body supports for the four prototype water gauges being made are finished.





As the nuts were being made I came to the end of the hexagonal brass rod that was being used to make them. It gets to the point when you can end up with a small length of rod that cannot be held to machine. The following photographs I hope can explain how it can be done. This wasn't really necessary as I have plenty of 5/16" hexagonal brass but I don't like ending up with small pieces of virtually unusable metal anyway sometimes you don't have plenty of metal.

Nut drilled and tapped but not completely parted off.





Other end in similar state.





One of the ends parted off.






After turning nut the work piece is moved further out of the chuck for cutting off the Jacob chuck being used to true it.





The other nut after being turned is sawn off while hand rotating the chuck.





Sawn off nut.





Nut left in chuck ready for facing.





Other end of nut finished.





With all the nuts completely machined they were finished using the tools shown. Top to bottom; gauge glass to check hole size. Die to clean thread for nut on water gauge body. Tap to clear thread in nut. Box spanner to hold nut while tapping and broaching. Brooch to make gauge glass hole in nut round and to size. Adjustable spanner the hold water gauge body while tapping.





Might be of interest I have found it very useful to have a large number of Die Stocks which the popular size dies I use are left in. It saves a lot of the not having to adjust them. I have other empty Die Stocks which are used for the less popular sizes of die.





Similarly the same with Jacob chucks I have two with different size of centre drills and others used repetitive jobs such has just been done. The use of both saves a lot of time. 






Both the die stocks and Jacob chucks for the most part were bought second hand from tool stores or alas more commonly at deceased members of my model club auctions. I have often thought how many hands some tools have go through in their life. When I was an apprentice we were expected to buy our own tools over the period of the apprenticeship (5 years) which in my case would cost nearly £300, not a lot? Well at the grand age of 21 I could expect to earn £12 to £15 a week. The reason for this rambling is that during my apprenticeship I was given the pair of hand vices below, they are Victorian or older and I have used and still use them for more than 45 years. I wonder how much longer they will be used? 






Later this week the water gauge top fittings and nuts will be made.

Regards Tony.


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## JAndrew (Nov 4, 2013)

Tony Bird,

Brilliant design, pictures and posts! Thanks for taking the time to post all the pictures and descriptions! I operated a small boiler in the navy that had gauge glasses like these but they were sealed with graphitic packing instead of o-rings. You learn real quick to start the boiler with the packing nuts only finger tight or else they crack right off the bat. Then you just bought yourself a 25+ valve tagout to re-replace them. As it was the things only seemed to last about a month or two.

I was wondering about one thing I saw in your post. It looks like you were able to hold hex bar in a collet for one of your operations? I didn't know you could do that? What type of collet is that and how many slits on it?

I also like your tangential tool holder. That's on my projects list.

Thanks again for all the clear, concise pictures of your incredible work!

-J.Andrew


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## tomfilery (Nov 5, 2013)

Tony,

 Great stuff - as usual - and nicely explained.

 I would most interested in you showing us how you do the version with the integral blow down valve - if you can find the time.

 Regards Tom


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## Tony Bird (Nov 5, 2013)

Hi,

Got on with the first of the top fittings today. Very similar to making the bottom fitting other than starting at its hole end rather than the threaded end. Missing out some of the machining that has been coverd before.

Centre drill.





6.2mm hole 1mm deep for '0' ring seating.





4.8mm hole through to transverse holes for 7/32"x 40 TPI thread.





Tapping 7/32" thread.





Parting off.





Hole for gauge glass is drilled from this side as it has to be as concentric as possible with the thread.

Centre.





4.2mm hole through for gauge glass shoulder and threaded.





Dry assembly.






Broaching hole for gauge glass and showing over heated joint! Must do better.





Staring on top nut shouldered and threaded 7/32"x 40 TPI.





Checking fit.





Facing.





'0' ring fitted.





Assembled next top fitting will have a deeper recess for the '0' ring.





Screws were shortened in the lathe using a file.





Preliminary assembly of water gauge fittings on the boiler showing copper washers and sealant to be used. Copper distance washers could be used by themselves which was always the way but I think that the sealant reduces to chance of de-zincing.





Fittings sealed being checked using a gauge glass before the sealant goes off.





Fitting glass.





Finished?

Forgot to put the last photograph on PhotoBucket.

I will go and find it.

Regards Tony.


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## Tony Bird (Nov 5, 2013)

Hi,

I cannot see for looking it was there!







Hi J.Andrew,

*I was wondering about one thing I saw in your post. It looks like you were able to hold hex bar in a collet for one of your operations? I didn't know you could do that? What type of collet is that and how many slits on it?*

The collet is an ER16 which is gripping the round threaded part of the work piece. Some collets can be used very carefully to hold both square and hexagonal stock. There are collets made that hold shaped stock. 


*I also like your tangential tool holder. That's on my projects list.*

Mine is an Australian made Diamond Tool holder which are made in both RH & LH in several sizes. I am very happy with it and rarely use any other tool



Hi Tom,

*I would most interested in you showing us how you do the version with the integral blow down valve - if you can find the time.*

I am happy with the way the water gauges have turned out, without too many alterations, I will have to start with the Tipex on the drawings while I still have notes of the alterations. Tomorrow I will finish the other hexagonal fitting and the two square ones. These four fittings were only prototypes before I make a batch, which will probably have square bodies. On previous occasions making water gauges I have made the top fittings completely and left the bottom fittings as parts so if necessary they can be made with blow down valves or with unions to be connected to satellite blow down valves. Using satellite valves can be quite useful for locomotives with enclosed cabs where the water gauge can be seen but no chance of getting fingers to the bottom fitting, they are also good for use on model boats for the same reason. Blow down valves on water gauges are also useful on small boilers for empting them.

After the completing the three water gauges I have a couple of simple boilers that have been hanging around to stick together. I expect the prototype gauges will be used on them. With other jobs on hand it will be several weeks before I start on a batch of water gauges but when I go I will make at least one with a blow down valve and add it to this thread.

Regards Tony.


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## Jasonb (Nov 5, 2013)

Tony, do you forsee any problems with dezincification of the brass which is in contact with the boiler water? Most commercially made ones and designs for making your own tend to specify bronze or GM and is what I have used on ones I have made in the past along with other boiler fittings such as clacks, blowdowns, plugs, etc.

J

EDIT forget that I missed page two.


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## SilverSanJuan (Nov 5, 2013)

Excellent work, Tony.  Thanks for posting all the detailed descriptions and photos.  Very helpful, indeed. 

Todd


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## RonGinger (Nov 5, 2013)

This 'dezincification' is a bit over the top. Has anyone ever seen an actual example of a brass fitting used in a model boiler that exhibited it? I know it is theoretically possible, but I want to hear from a person having seen a real case.

I saw it happen to brass screws on a wood boat once, but the boat was over 40 years old at the time, and of course the screws were  under water for about half of each year.

For a model boiler, with infrequent use, and the water only in contact with the end of the screwed  parts and the internal passages it seems highly unlikely to ever be a problem.

So, someone have an example to show us?


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## Tony Bird (Nov 6, 2013)

Hi Ron,


*This 'dezincification' is a bit over the top. Has anyone ever seen an actual example of a brass fitting used in a model boiler that exhibited it? I know it is theoretically possible, but I want to hear from a person having seen a real case. I saw it happen to brass screws on a wood boat once, but the boat was over 40 years old at the time, and of course the screws were under water for about half of each year. For a model boiler, with infrequent use, and the water only in contact with the end of the screwed parts and the internal passages it seems highly unlikely to ever be a problem.*

_*So, someone have an example to show us? *_

I have never seen any boiler fittings that I have thought had been effected by dezincification, presumably only the fittings below the water level of the boiler would be effected i.e. bottom water gauge fitting, blow down valve and clacks. I have had fittings break when removing them from boilers that have been used a lot, which I had put down to the fitting being seized, due to mineral (calcium?) forming around the thread. The fittings themselves aren't very strong, a fairly thin wall threaded tube pulling a shoulder against a bush isn't very strong. I haven't seen any visual evidence of thread deterioration on fittings removed from boilers however the type of water used might effect the reaction, I use mostly filtered rainwater (we get a lot in Old South Wales).

I have seen the effect of dezincification in brass model/toy boilers that I have repaired, these boiler shells are often very thin when new and become porous at there bottom where un drained water might lie. The boilers even when cold seem to sweat water before breaking through. I have a failed brass boiler on a locomotive somewhere, I will dig it out and photograph it.

I have had a quick look through The Examination & Testing of Miniature Steam Boilers (Revised Edition 2012).

I cannot find any reference to what boiler fittings should be made from except in Section 13.5 (b) Copper boilers should also be laid up dry to minimise the problem of dezincification of any brass fittings.

Does anyone know of a publication that lists materials that are mandatory for the construction of boiler that the insurance companies will accept?


Regards Tony.


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## Tony Bird (Nov 6, 2013)

Hi,





The first of the square body water gauges has been fitted to a boiler.

As promised photographs of what I think is de zincing. The locomotive was commercially made in 1984 and was used quite a lot over the next twenty years when the boiler failed, I must get around to making a new copper boiler for it.













Well this is the end of this thread I think.

Regards Tony.


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## modeng2000 (Nov 6, 2013)

Well Tony, I just wanted to say how much your information has been helpful to me - A LOT - thanks.

Your boiler build is a valuable reference for anyone making a boiler. It occurred to me that you might put both the boiler build and the fittings together as say a PDF file for folks to download and keep. Easy to say but I don't know how much work is involved.

John


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## Tony Bird (Nov 7, 2013)

Hi John,

Glad you enjoyed it.  Alas my computer skills are not up to what you suggest. If anyone would like to do it, please do.

Regards Tony.


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## Gedeon Spilett (Nov 7, 2013)

An advice that was given to me recently (ie not yet tested) is to put a small copper wire into the gauge glass, to limit the blocking  by air bubbles while filling the boiler.  

Too sad for this little loco...hey, only one boiler is required, you do not have to do a batch!


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## Tony Bird (Nov 8, 2013)

Hi Gedeon,

*An advice that was given to me recently (ie not yet tested) is to put a small copper wire into the gauge glass, to limit the blocking by air bubbles while filling the boiler. *

I also have heard but never tried this, I have two small boat boilers to build so will try it on one of them and report results

*Too sad for this little loco...hey, only one boiler is required, you do not have to do a batch! *

The model locomotive is a Merlin/Beck with obviously a brass boiler which has a non standard OD. Also the regulator/lubricator is in its steam dome which is odd. I will have another look at it, you are quite right I should do something about it, but so many other jobs!

Regards Tony.


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## KBC (Nov 9, 2013)

Does anyone know of a publication that lists materials that are  mandatory for the construction of boiler that the insurance companies  will accept?


Regards Tony.

Hi Tony,
Further to your question on boiler materials, I can only assume that the insurance companies rely on the Model Engineering Societies ability to test boilers but as to what materials the Companies will accept is unknown.

It would appear that the only publication stating boiler materials and Calc's for designs is K.N.Harris's book MODEL BOILERS & BOILERMAKING 

Copper for the shell is the preferred material and and easier for the amateur to work with .
Phos Bronze or Gun metal for boiler bushes, brass is frowned upon as the high temps required to melt silver solder can destroy the thread in the brass and can cause failure to the fittings.
Boiler stays to be Monel metal or Phos bronze, brass stays are not mentioned but I suppose it's the same problem with the threads being weakened by the heat and eventual corrosion.

I can only assume that as you are an experienced builder that you have a copy of the above mentioned book, if not I would recommend that you get one.

The fitting of a copper rod into the sight glass does stop bubbles forming it breaks the surface tension of the bubble allowing a true reading, modelers use the copper wire stripped from electrical cable.

I hope this helps, not a definitive answer but like you I have never been able to find out how the Insurance companies set what materials must be used and the Regs are more to do with Loco boilers with Marine boilers as an after thought.

George.


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## Tony Bird (Nov 10, 2013)

Hi George,

*I can only assume that as you are an experienced builder that you have a copy of the above mentioned book, if not I would recommend that you get one.
*
I have made a few boiler of different types and sizes all to the spec's suggested in both K.N.H. and Martin Evans books.  Most of the removable fittings have been made from brass,  I make most fittings but always assumed the ones bought were also made from brass, apparently not?

I think I will continue to use brass until I know bronze and monometal become mandatory.

Regards Tony.


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## KBC (Nov 10, 2013)

Tony Bird said:


> Hi George,
> 
> *I can only assume that as you are an experienced builder that you have a copy of the above mentioned book, if not I would recommend that you get one.
> *
> ...



Hi Tony,
I don't think that any other metal other than brass will be made mandatory for fittings.
Over the years that I have been making boilers and fittings there has never been any other metal with the sections that can be had with brass, for instance Phos bronze and Monel are not available in the Hex range that can be had in brass, plus the cost would be prohibitive if they were available and I don't know of a supplier who makes fittings other than in brass.
Like you I make all of my own fittings from brass and will continue to do so.

George.


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## Niceonetidy (Dec 15, 2013)

KBC said:


> Hi Tony,
> I don't think that any other metal other than brass will be made mandatory for fittings.
> Over the years that I have been making boilers and fittings there has never been any other metal with the sections that can be had with brass, for instance Phos bronze and Monel are not available in the Hex range that can be had in brass, plus the cost would be prohibitive if they were available and I don't know of a supplier who makes fittings other than in brass.
> Like you I make all of my own fittings from brass and will continue to do so.
> ...



Smith metals sell phosphor bronze hexagon bar, and short pieces too


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## Steamchick (Jul 25, 2022)

Tony, This may be an old thread, but a really "good 'un". Many items covered that confirmed I do a sensible job making my water gauges. (But I cheat and use proprietary nuts!). I like your graving, I haven't come across anyone else doing this, but my Grandfather taught me when I was a boy, so I use it as a quick way to do odd bits - just as you do.
And all your little tricks - like a wire in the tailstock chuck to catch the part being parted-off... I use regularly.
Also I use the same tool bit holder as you, (Home made).
On de-zincification. I had a brass screw in the bottom (drain point) for the bottom fitting - that obviously didn't naturally drain when the boiler was blown-down. After at least 10 years of use, it leaked then simply crumbled when I did the annual fill and hydraulic test. Cleaned it out with a cocktail stick and pipe cleaner! But the gauge fittings in Brass are still OK 15 years later. So may be just the screw material was not as good? (More ZInc?).
Thanks for the excellent thread.
K2


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## Johan Maritz (Aug 31, 2022)

Very good write up and a very needed one for me. I have been studying literature and drawings for weeks now on how to make these fittings. This comes at a most welcome time. Thanks Tony, very good tips there as well, experience shows.


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## delalio (Sep 2, 2022)

Mr Tony Bird,

I have been meaning to make various gauge glasses for a few of my locos / projects I am working on, and had been putting them off for a while. Finding decent and accurate drawings or details was quite tricky. I had dome some drawings myself, but not taken the plunge to actually fabricate any as yet. Your post has spurred me on, and I will try and do some this weekend! So thank you.

I will be videoing my progress and will post a video in the near future. (Depending on how successful I am! ha)

Thankyou again for your very detailed post. I may return with some questions if that is ok!


Kindest Regards,

Del


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## ajoeiam (Sep 3, 2022)

delalio said:


> Mr Tony Bird,
> 
> I have been meaning to make various gauge glasses for a few of my locos / projects I am working on, and had been putting them off for a while. Finding decent and accurate drawings or details was quite tricky. I had dome some drawings myself, but not taken the plunge to actually fabricate any as yet. Your post has spurred me on, and I will try and do some this weekend! So thank you.
> 
> ...


Speaking only for myself - - - - please offer your results in written form with pictures. 
I find videos problematic for a number of reasons 
1. storage space
2. plethora of poorly compatible formats 
3. huge amount of time to view 
4. tough to do well 

Please - - - its one vote for a write up w photos. 

TIA


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## terryd (Sep 4, 2022)

Tony Bird said:


> Hi,
> 
> I cannot see for looking it was there!
> 
> ...


Hi Tony/Andrew,

Just out of intrest I have a mid 19thC (around 1860 ish) workshop .practice book showing two examples of these 'Diamond' type tangential cutting tools.  Just goes to show that there is little new in the world of manufacturing until you get major technological shift such as NC and computer control.

TerryD


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## Steamchick (Sep 22, 2022)

Jasonb said:


> Tony, do you forsee any problems with dezincification of the brass which is in contact with the boiler water? Most commercially made ones and designs for making your own tend to specify bronze or GM and is what I have used on ones I have made in the past along with other boiler fittings such as clacks, blowdowns, plugs, etc.
> 
> J


Hi Jason. A good question about de-zincification: 
I think it depends on the specific grade of brass, as to how long it can last when permanently wetted. Also, the combination of metals in the proximity of the water (acting as an electrolyte) will cause the "highest electro-potential" metal to be sacrificed first (The highest concentration of zinc). The recommendation is to use Bronze (zinc free) for all silver soldered bushes, and fittings that screw into those bushes, then brass can be used on anything that is readily replaceable, such as the water gauge fittings away from the bronze joint at the boiler.
I use "snow" water, rainwater or the ice-water when I defrost a freezer, which is probably almost pure distilled water, so is relatively corrosive as an electrolyte for any mixed-metal container. But I have no scale in my boilers.
The real key to safety is an annual inspection, checking everything each time before firing, and when at pressure (Drop the fire if steam leaks have developed! - before a fitting blows apart with disastrous steam expulsion!). And drain after EVERY use of a boiler. (Dry metal doesn't corrode significantly).
Hope this helps.
K2


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## terryd (Sep 22, 2022)

Steamchick said:


> Hi Jason. A good question about de-zincification:
> I think it depends on the specific grade of brass, as to how long it can last when permanently wetted. Also, the combination of metals in the proximity of the water (acting as an electrolyte) will cause the "highest electro-potential" metal to be sacrificed first (The highest concentration of zinc). The recommendation is to use Bronze (zinc free) for all silver soldered bushes, and fittings that screw into those bushes, then brass can be used on anything that is readily replaceable, such as the water gauge fittings away from the bronze joint at the boiler.
> I use "snow" water, rainwater or the ice-water when I defrost a freezer, which is probably almost pure distilled water, so is relatively corrosive as an electrolyte for any mixed-metal container. But I have no scale in my boilers.
> The real key to safety is an annual inspection, checking everything each time before firing, and when at pressure (Drop the fire if steam leaks have developed! - before a fitting blows apart with disastrous steam expulsion!). And drain after EVERY use of a boiler. (Dry metal doesn't corrode significantly).
> ...


Hi Jason/K2.

Although I build boilers as copper/bronze with replaceable brass fittings I also possess a couple of Mamod locos and a stationary engine of the same pedigree and always wondered how they've got away with brass boilers for so long?  A special alloy perhaps but doesnt look any different to most of my sheet brass

Regards

TerryD


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## terryd (Sep 22, 2022)

Steamchick said:


> Hi Jason. A good question about de-zincification:
> I think it depends on the specific grade of brass, as to how long it can last when permanently wetted. Also, the combination of metals in the proximity of the water (acting as an electrolyte) will cause the "highest electro-potential" metal to be sacrificed first (The highest concentration of zinc). The recommendation is to use Bronze (zinc free) for all silver soldered bushes, and fittings that screw into those bushes, then brass can be used on anything that is readily replaceable, such as the water gauge fittings away from the bronze joint at the boiler.
> I use "snow" water, rainwater or the ice-water when I defrost a freezer, which is probably almost pure distilled water, so is relatively corrosive as an electrolyte for any mixed-metal container. But I have no scale in my boilers.
> The real key to safety is an annual inspection, checking everything each time before firing, and when at pressure (Drop the fire if steam leaks have developed! - before a fitting blows apart with disastrous steam expulsion!). And drain after EVERY use of a boiler. (Dry metal doesn't corrode significantly).
> ...


HiK2,

   I thought, from schoolboy chemistry that water without any pollutants i.e. pure water is not a conductor of electricity so not sure how it stimulates a galvanic reaction between dissimilar metals.  Of course rai/snow water isn't pure as it picks up contaminants from the air becoming acidic, either dilute sulphuric or carbonic, possibly both, as well as dust and soot particles which helps make it conductive. An interesting event was when Alec Rose circumnavigated the globe in his yawl Lively Lady and had to stop in New Zealand reportedly to repair a 'broken mast'  the problem actually was that he had stinless steel fittings on an aluminium mast and the salt sea water cause galvanic corrosion,.  In NZ he had mild steel ( may have been forged) fittings to replace the stainless ones and the problem was solved.  
  When I was teaching, in basic materials science I used to demonstrate the corrosion of stainless by mounting a small piecre of stainless steel sheet and used a rubber band around the assembly to hold the steel in the wood and left it hanging in a strongish salt solution over a weekend, by mondauy morning the band had caused a groove about 10 mm deep into the steel.  The idea was to show how stainless steel body parts on a car canbe prone to corrosionunder pressure (tight bolt?) in a salty environment WInter roads).  The pupils were mos impressed tha a rubber band could cut stailnless steel 

Regards
TerryD


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## Steamchick (Sep 22, 2022)

Hi Terry,
One of the curiosities of chemistry is that distilled water PH 7 acts like a mild acid with dissimilar metals re: electrolytic corrosion. I checked it on Wikipedia (if you believe that?) on a different thread.
I am not a chemist, so can't explain it. But it may be something to do with electro-potential of hydrogen ions versus some metal ions?

K2


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## Steamchick (Sep 22, 2022)

Hi again Terry.
On Mamod brass boilers... I can only guess that if all the brass is the same grade, with no other metals present, then there is no electro-potential to develop de-zincification?
K2


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## terryd (Sep 22, 2022)

Steamchick said:


> Hi Terry,
> One of the curiosities of chemistry is that distilled water PH 7 acts like a mild acid with dissimilar metals re: electrolytic corrosion. I checked it on Wikipedia (if you believe that?) on a different thread.
> I am not a chemist, so can't explain it. But it may be something to do with electro-potential of hydrogen ions versus some metal ions?
> 
> K2


Hi K2,

That's interesting, thanks.  Do you have the link to the Wikipedia article, my inquisitive nature is taking over 

TerryD


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## terryd (Sep 22, 2022)

Steamchick said:


> Hi again Terry.
> On Mamod brass boilers... I can only guess that if all the brass is the same grade, with no other metals present, then there is no electro-potential to develop de-zincification?
> K2


Hi,

I figured that one out myself, but surely the brass for the fittings and bushes etc would be of different composition than the sheet brass used for the shell as they need different properties for the different manufacturing processes? Too many differences here.

Rgeards
TerryD


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## Steamchick (Sep 22, 2022)

Data sheet - off the web:


			https://www.chemicals.co.uk/uploads/documents/44%20-%202654%20-%20SDS11558.pdf
		









						Is Distilled water corrosive? - Answers
					

Typically no. It does depend on the processing of the water however. If there is post filtering that removes the minerals and leaves it essentially pure H2O, then you have a relatively aggressive solvent. Distillation alone is not capable of producing water pure enough to have this property.




					www.answers.com
				












						Why Is Dimineralized Water Corrosive? - Industrial Professionals
					

Why Is Dimineralized Water Corrosive? - posted in Industrial Professionals: dear all as most DM water tanks/drums that I have ever seen in different industries are made from SS , does anybody know exactly why DM water is Corrosive?




					www.cheresources.com
				



Araboni:

Dimineralized Water is NOT corrosive. Let's agree on that fact. However, contaminated DM water IS corrosive - especially if contaminated with dissolved oxygen or carbon dioxide.

If oxygen is present, you get one form of corrosion: rust (or iron oxidation). If carbon dioxide is present, you get acidic attack on the steel with resulting acid etching of the steel. Both types are corrosive.

If your DM is stripped of all dissolved gases and is truly pure H2O, then you should have no corrosion. It is the contaminants that give problems - not the water.









						What is Distilled Water? - Definition from Corrosionpedia
					

This definition explains the meaning of Distilled Water and why it matters.




					www.corrosionpedia.com
				



Corrosionpedia Explains Distilled Water
Raw water usually contains a number of microscopic contaminants, along with dissolved minerals, such as calcium and iron. These elements can be removed from water through boiling until water changes to steam; this process known as distillation. When the steam is allowed to cool down and condense into liquid, the resulting purified water is called distilled water.

When water is heated in a distiller, any dissolved solids, such as salt, bacteria, calcium or iron, remain solid while the pure water converts to a much lighter steam and is drawn out for condensation. This water should ideally be nothing but hydrogen and oxygen molecules, with a pH level of 7 and no additional gases, minerals or contaminants.

Since the minerals and ions typically found in tap water can be corrosive to internal engine components, distilled water is preferable to tap water for use in automotive cooling systems. Similarly, it is also used in model steam engine boilers and model engines of other types to prevent scale buildup.

Despite its benefits, distilled water is particularly corrosive. With no minerals to give the water pH balance, distilled water acts like a magnet, absorbing chemicals (phthalates and bisphenols) from plastics, nickel from stainless steel, aluminum from aluminum containers, and carbon dioxide from the air.

There is loads of information on the web... these are just a few postings.
I was also taught (by a water expert - supplying "pure water" for a laboratory system) - This water is more corrosive than regular tap water, so DON'T use it in car cooling systems - or anything similar - without corrosion inhibitors. He also tested and approved the water we mixed with Long-Life Coolant - to make the 50% mix for filling new cars. (Up to 1/2 million per year).
The phrase that hits me as obvious... (I'm sure I was taught this in School Chemistry at about the age of 11 or 12?):
"Despite its benefits, distilled water is particularly corrosive. " - Seems to sum it up?
K2


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## terryd (Sep 23, 2022)

Steamchick said:


> .......................
> 
> There is loads of information on the web... these are just a few postings.
> I was also taught (by a water expert - supplying "pure water" for a laboratory system) - This water is more corrosive than regular tap water, so DON'T use it in car cooling systems - or anything similar - without corrosion inhibitors. He also tested and approved the water we mixed with Long-Life Coolant - to make the 50% mix for filling new cars. (Up to 1/2 million per year).
> ...


Hi K2,
  Interesting reading. Having read the documents you posted it seems that it is any pollutants which make it corrosive not the water itself.  I would think that CO2 dissolved would be particularly bad as it produces carbonic acid, after all that is the main cause of acid rain along with sulphur dioxide, but the documents only mention corrosion not galvanic action with distillled and DM water.  I am not enough of a chemist to understand how Mamod et al get away with brass boilers, perhaps you're correct about them not having dissimilar metals in the construction.
  Your referral to car cooling systems reminds me of the problems we had with Triumph Stags in the 70s.  The engines suffered terribly from overheating and the water pump was blamed.  However it turned out that the engine had a galvanic reaction problem with aluminium cylinder heads and cast iron cylinder block.  This caused the narrow waterways of the heads to clog with aluminium sulphate and this in turn obviously prevented water flow.  It was mostly caused by owners using water to fill the cooling system without any inhibitor such as is in antifreeze solutions.  It was seen as too expensive to use.  Mnd you it was also caused by the poor quality of those heads as they were cast by a third party not inhouse as the Stag was rushed into production early, I have see porous castings and some even had the core sand left in the waterways, it was a disaster for BMC.

Regards
TerryD


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## Drawfiler (Sep 23, 2022)

Brass is a mixture not a genuine alloy, ie the crystals of zinc and copper are discrete and not combined, when subjected to a suitable environment the zinc dissolves leaving a copper honeycomb which is structurally weak and leads to component failure.
The other problem is stress corrosion when the component despite being over engineered fails because it stressed while in a corrosive atmosphere. This was discovered in the ‘60s when building fixings made in Manganese bronze failed in city conditions.
The crystalline structure does help us as lead in commercial brass also exists as crystals which shear easily during machining so breaking up the chips and giving lower ductility leading to better finish.
As others say, dont use brass for fittings.


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## Steamchick (Sep 23, 2022)

Thanks Terry, Interesting about the Stag engines... but I know technology has moved on and cores are made from mixes of stuff so tales of cores being full of sand are history.... But I didn't know the corrosion was Aluminium Sulphate.  I wonder where the Sulphur came from? I would have guessed Aluminium Carbonate... from dissolved CO2... or perhaps Magnesium or Calcium carbonate dissolved in tap water...? Maybe there was Mag. Sulphate in the tap water?
On conductivity... It is of course the free ions from solutes in water as a solvent that conduct.... I.E. dissolved gases from the air. Snow and rain have a chance to dissolve everything as they form from condensing vapour in clouds... and hang around for some time in the air before dropping on us! I think snow is purer, than rain because the snow crystals form directly from vapour and being solid and so cold at high altitude do not absorb gases radily? - But that is my GUESS!.
Rain on the other hand is melted snow, or simply condensate, that has fallen from a great height and in doing so will absorb air molecules and have a mix of gasses, particularly O2 and CO2 it seems...
I'm learning all the time...
K2


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## terryd (Sep 23, 2022)

Drawfiler said:


> Brass is a mixture not a genuine alloy, ie the crystals of zinc and copper are discrete and not combined, when subjected to a suitable environment the zinc dissolves leaving a copper honeycomb which is structurally weak and leads to component failure.
> The other problem is stress corrosion when the component despite being over engineered fails because it stressed while in a corrosive atmosphere. This was discovered in the ‘60s when building fixings made in Manganese bronze failed in city conditions.
> The crystalline structure does help us as lead in commercial brass also exists as crystals which shear easily during machining so breaking up the chips and giving lower ductility leading to better finish.
> As others say, dont use brass for fittings.


Hi Df,

 Surely the zinc from brass wouldn't dissolve in neutral water?  it is basically insoluble in that condition, like many other metals such as aluminium it form,s in this case, a protective layer of insoluble zinc hydroxide, which has to be stripped away for any corrosion to take place. 

 The example I gave in an earlier post of the forced stress corrosion of Stainless steel in a suitable environment demonstrated the process.

 Ever since I started work as an apprentice engineer in '63 we were always told, as in the modern model engineering that permanent boiler fittings such as bushes shoult not be made of brass but os bronze but it is ok to make removeable fittings from brass as they can be replaced if problems arise.  I'm just renovating a Stuart 504 boiler which has been used for at least 50 years, I know it's providence and the brass fittings including those for the sight glass, sitting now in a weak acid bath to clean up are in apparently perfect condition after a great deal of use.

Best regards

TerryD


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## terryd (Sep 23, 2022)

Steamchick said:


> Thanks Terry, Interesting about the Stag engines... but I know technology has moved on and cores are made from mixes of stuff so tales of cores being full of sand are history.... But I didn't know the corrosion was Aluminium Sulphate.  I wonder where the Sulphur came from? I would have guessed Aluminium Carbonate... from dissolved CO2... or perhaps Magnesium or Calcium carbonate dissolved in tap water...? Maybe there was Mag. Sulphate in the tap water?
> On conductivity... It is of course the free ions from solutes in water as a solvent that conduct.... I.E. dissolved gases from the air. Snow and rain have a chance to dissolve everything as they form from condensing vapour in clouds... and hang around for some time in the air before dropping on us! I think snow is purer, than rain because the snow crystals form directly from vapour and being solid and so cold at high altitude do not absorb gases radily? - But that is my GUESS!.
> Rain on the other hand is melted snow, or simply condensate, that has fallen from a great height and in doing so will absorb air molecules and have a mix of gasses, particularly O2 and CO2 it seems...
> I'm learning all the time...
> K2


Hi K2,

If I'm quick enough to catch any snow, which seems to be a rare occurance these days, I'll carry out some ph tests to prove your theory.  However we seem to generally have liitle snow during recent winters, I was employed in Edinburgh from June 21 to june 22 and we only had about 3 days of very light snow during th ewhole winter period, I probably couldn't have collected any without some ground pollution, I don't know what it was like down here in England at that time.

And the Stag thing it probably was Aluminium Carbonate come to think of it, my old mind gets forgetful of facts these days it was many years ago.  I've had very little real experience of casting except for simple aluminium greensand casting when I was teaching metalwork and we used to make cored from coarse sand, isinglass and condition them with CO2.

Regrds

TerryD


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## Bentwings (Sep 23, 2022)

Steamchick said:


> Hi Terry,in the automotive world there are coolant ph testers that test the coolants especially on big over the road trucks. I used a few but really did not understand them basically you just adjusted the coolant antifreeze to color a specific range on the chart or flags as they were called   Some times adding distilled water some times just plan water or coolant  I don’t recall if there was a numeric value . There was little explanation on the instruction as to what you were doing other than balancing the ph level . Big truck radiators and cooling itemsarevprettyvexpensive and often expensive labor wise to replace so it was an important but little understood thing .   My big boat was loaded with anodes everywhere many were yearly replaced others were longer lasting this was fresh water boat. I’ve often heard the salt water boaters complaine about coorosion and the need for anode maintenance .
> One of the curiosities of chemistry is that distilled water PH 7 acts like a mild acid with dissimilar metals re: electrolytic corrosion. I checked it on Wikipedia (if you believe that?) on a different thread.
> I am not a chemist, so can't explain it. But it may be something to do with electro-potential of hydrogen ions versus some metal ions?
> 
> K2


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## Steamchick (Sep 24, 2022)

Hi, It seems that Bentwings has attributed the truck cooling system and boat stuff to me, but that is his bit. My bit is just the comment re- "PH". - Just for the record.
But I remember using PH papers and colourant in Chemistry at school, when titrating solutions.
Terry, you are right, I think, about the dissolved gases in distilled water  - or de-ionised water - causing corrosion. I reckon you know more chemistry than I!
Drawfiler, Please teach us more metallurgy. This is all new to me. I like to learn "why" things are what they are....
K2


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## Bentwings (Sep 26, 2022)

terryd said:


> Hi K2,sorry I didn’t mean to sound rough I was just posting experience . Interesting I worked at international diesel that made Ford 6.0 v 8 diesels. Ultimately Ford had a massive recal of the 6.0 diesel. I think they stopped production entirely for a while . They had about every problem in the book . They had to use special coolant as the diesel produced some kind of harmonics that caused the lower cylinder to crack in the block. Some how the new coolant solved this for a while .     Had nothing to do with corrosion .  My grand son has one of these now and it’s been a confining source of issues . The radiator being one of them .  Salt water boats have problems but fresh water ones do too. In the winter when they are hauled out they are pressure washed to remove algae and invasive  groth  then we changed anodes and cleaned the props and underwater metals  most are stainless steel so more or less non coorosive    They don’t use radiators but use heat exchangers  these require service and expensive replacements  if mufflers are not drained they freeze and split  not fun replacing
> 
> I liked my Cummins diesel it’s got 450 k on it  still runs good no corrosion   I put one radiator in it due to cracking road salt is the worst enemy up here in north land
> 
> ...


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## Bentwings (Sep 26, 2022)

Steamchick said:


> the distilled water is interesting I had some and used it in a humidifier thinking it was good . Ruined the humidifier .
> Data sheet - off the web:
> 
> 
> ...


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