# Silver braze/solder



## Ripcrow (Apr 6, 2014)

Can someone explain the difference between the amount of silver in the rod and what effect this has on the strength of the weld and the materials to be joined,my local supplier has 2% 15% and 30% rods from 1.6 mm to 3.5 mm rods,I purchased some 2% 2.5 mm rids and tried them their melting point is quite higher than expected and also I notice little gas bubbles in one of my failed welds,I've never done this type of work before so any advice will be appreciated


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## goldstar31 (Apr 7, 2014)

Might I respectfully suggest that you read and re-read much the same topic of perhaps only a few days ago. I've been up and down the length of the UK since and my memory is fragmented because of that and old age.

 Initially, I doubt that a beginner will succeed using rods which have a high melting point because the silver content is virtually non existent. Once you have melted 2% stuff, you will have next to no silver left to speak of. Consequently, you will be trying to melt something with an even higher melting point. So instead of silver soldering, you are attempting to braze because that is what you have left. You need a lot of heat or if I may be forgiven, A LOT!
 Once you have a proper braze joint, it will be far stronger than a silver solder one- but you have porosity. You have either impurities or air or both and are using the wrong technique and heat to get them out. I think that I attempted to explain this. 

 At this part of your questions, no one knows what you are doing and equally important, what you are using. Basically, you have two roads. Either you bite the bullet and get your wallet spanner out and buy high silver stuff or get your heat sufficient to melt what amounts to brazing rod and its somewhat different technique. With the latter, if you are making small engines out of brass, you stand a high chance that your efforts in machining will distort or melt. On the other hand, if you are mending the garden gate, silver solder is an obvious waste. 

 I hope that this helps

 Norman


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## Loose nut (Apr 8, 2014)

Try this website there is a lot of tech info on solder there. May have strength comparisons. 

Usually for models the silver content is near 50%. Easyflow #2 (England 42%) or Easyflow 45 (North America 45%).

The trick to a good silver braze job is the right flux and how to use it.

http://www.lucasmilhaupt.com/en-US/products/fillermetals/1/


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## Entropy455 (Apr 8, 2014)

The difference between brazing and soldering is the temperature in which the filler material melts. Greater than 800 degrees is brazing, less than 800 degrees is soldering. Overseas, everyone seems to call silver-brazing silver soldering - which is fine, provided they understand the proper flux and heat requirements needed to make the joint.

You must be careful with silver brazing rod, as some of it contains cadmium. Cadmium will out-gas at temperatures greater than 400 degrees F, and will harm you if inhaled (or ingested). Here in the US, our low-temp silver brazing rod is 20% cadmium by weight, and melts just under 1300 degrees F. The advantage to the cadmium, is that the silver-brazing alloy flows very freely (low viscosity)  which is good for brazing pipe joints. Whereas cadmium-free silver rod melts at over 1600 degrees F, and flows more like peanut butter  which is good if youre trying to make fillet type joints  for general joining of parts.

Your base materials must have a higher melting temperature than your brazing material, or youll melt your parts.

Bronze melts hot
Silver melts less hot
60/40 lead-tin solder melts the least hot

Flux is used to encourage the wetting action of the filler material onto your base materials. There are a wide range of fluxes.


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## goldstar31 (Apr 9, 2014)

Entropy455 said:


> The difference between brazing and soldering is the temperature in which the filler material melts. Greater than 800 degrees is brazing, less than 800 degrees is soldering. Overseas, everyone seems to call silver-brazing silver soldering - which is fine, provided they understand the proper flux and heat requirements needed to make the joint.


 
 Respectfully, the answer is 'No' Twice!

 In France, the joining process is 'Soudure' for all this airy fairy sticking things together- with metal. To our untutored translation that is 'soldering'

 Again, we Brits use the words 'Soft soldering', Hard soldering, Lead loading, tinning, brazing, welding, Tig-ing, Mig-ing and a plethora of words to define the simple joining process.

 Sticking metal together is and never was much of a problem. Ask your dear old girls who stuck your wonderful Liberty Ships from the Henry Kaiser Yards to help sort out a beleaguered Britain where I grew up. 

 Norman


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## Swifty (Apr 9, 2014)

Well, I'm still convinced that according to my experience, silver soldering is done with flux and a various silver content rod that flows into the joint with minimum solder showing, whilst brazing, using flux and a brazing rod, sits on the joint similar to welding. Entrophy455 mentioned that "_overseas that call it silver soldering" _instead of silver brazing, maybe its only the US that's the odd one out.

There are pictures on this link showing brazed joints.
http://forums.mtbr.com/frame-building/you-suck-brazing-601866.html

Paul.


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## Hopper (Apr 9, 2014)

Swifty said:


> Well, I'm still convinced that according to my experience, silver soldering is done with flux and a various silver content rod that flows into the joint with minimum solder showing, whilst brazing, using flux and a brazing rod, sits on the joint similar to welding. Entrophy455 mentioned that "_overseas that call it silver soldering" _instead of silver brazing, maybe its only the US that's the odd one out.
> 
> There are pictures on this link showing brazed joints.
> http://forums.mtbr.com/frame-building/you-suck-brazing-601866.html
> ...



Yes, here in Oz, silver soldering generally refers to using EasyFlo 40-50 per cent silver solder, which is silver in colour. Can be done with oxy or with propane torch if the job is not too big.

Brazing, here in Oz , generally refers to using the yellow coloured brass rod and an oxy torch to join two bits of metal.

But it gets complicated because there is also sif-bronze welding which requires special technique and is used on Norton motorbike frames and their replicas. Seems the Brits claim to specialize in this technique.

And now the Strine gumment in its infinite wisdom has banned lead from solder for plumbing, so that solder now comes with 2 per cent silver and is marketed as "silver solder", confusing the heck out of everyone.

Back to the OP, there is a very good book in the Workshop Practice series on Soldering and Brazing that is well worth a read.


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## GWRdriver (Apr 9, 2014)

Swifty said:


> Well, I'm still convinced that according to my experience, silver soldering is done with flux and a various silver content rod that flows into the joint with minimum solder showing, whilst brazing, using flux and a brazing rod, sits on the joint similar to welding


That's exactly how I would describe it.





> Entrophy455 mentioned that "_overseas that call it silver soldering" _instead of silver brazing, maybe its only the US that's the odd one out. - Paul


Paul,
It's only a very few who insist upon calling it brazing.  The majority of model engineers and live steamers in the USA use "silver solder."  I think the confusion about brazing arose some years ago with the great increase in Gauge 1 live steam activity in the USA and the subsequent desire of folks to build their own boilers.  At that time many DIY big box shops were selling solder products labeled "Silver Solder" but which were actually silver bearing solder (when you read the fine print.)  Folks momentarily flocked to this because it avoided costly torch gear and special flux, resulting in unusable, or at least unsafe, results.  At that point some people began to use silver brazing to distinguish between high temp and low temp silver solders.  Even the largest US manufacturer of silver soldering materials labels their products "Silver Solder."


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## chucketn (Apr 9, 2014)

I agree with Hoppers' explanation. That's how I learned it many years ago. My Dad could lead solder, silver solder, braze or weld with stick or oxy/acet. I now have his B tank and torch set. I wasn't taught by him how to solder, and have fallen for the silver bearing vs silver solder hype myself. Miss him terrably...
Chuck


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## TimTaylor (Apr 9, 2014)

The following link will provide you with more information than you probably want to know about a wide variety solders and their applications:

http://en.wikipedia.org/wiki/Solder


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## chucketn (Apr 9, 2014)

Thanks for the Wikipedia link, Tim. I taught High Reliability Soldering for the USAF at a Field Training Detachment for almost 10 years, and there was info in that link I didn't know!

Chuck


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## Entropy455 (Apr 9, 2014)

GWRdriver said:


> Even the largest US manufacturer of silver soldering materials labels their products "Silver Solder."



Curious - which manufacturer might that be?

http://www.harrisproductsgroup.com/en/Products.aspx

Above is a link for a large manufacturer & global distributor of brazing and soldering alloys. Note that they advertise a silver-solder within the "soldering" section, that melts well under 800 degrees F. Also note that silver brazing rod is labeled and advertised within the "brazing" section, and melts over 800 degrees F.

One alloy is safe for elevated temperature & pressure steam joints, whereas the other alloy would be very dangerous (as others have already pointed out.) It's an unsafe practice to identify a brazing operation as soldering.

Whenever I task a pipe-fitter to makeup a brazed joint, I identify the piping base material, the fitting base material, the required flux, the required silver alloy, system fluid, system operating temperature, and operating pressure. I also task any non-destructive testing requirements that I require - such as a hydrostatic tests, VT inspections, UT inspections, etc - depending on the criticality of the joint.

Please don't take offense to my comment that overseas folks often call silver-brazing by the wrong term - as it happens to be a true statement. Besides, here in the US we have more than our share of screwed up technical terminology. . . . .


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## Ripcrow (Apr 10, 2014)

I had a lot of trouble finding silver solder in aus every time I asked for it I got a dumb look or got shown the little roll of silver solder for electrical work,it wasn't until I asked for silver braze that I got what I needed just wasn't sure on strength verses silver content properties.thanks for all your replies


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## TimTaylor (Apr 10, 2014)

Ripcrow,

Sorry if you got buried with too much info - here's the simple difference:

Both silver solder and silver braze alloy are Sn/Ag alloys.

Silver solder has silver content in the 3-5% range and melts in the 424-570 deg F range

Sliver braze alloy has silver content in the 30-50% range and melts at 1100 def F or higher

The higher silver content of silver braze alloy makes it significantly stronger. 

It should also be noted that a good brazed joint relies on capillary action drawing the braze filler into the joint, so clearances are important. Optimum joint strength is achieved with clearances in the 0.002"-0.003" range. 

Hope this makes it a little clearer.....

Tim


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## robmort (Apr 10, 2014)

From the Cupalloys site:
'One definition in British Standards defines brazing as : "a  process of joining generally applied to metals in which, during or  after heating, molten filler is drawn into or retained in the space  between closely adjacent surfaces of the parts to be joined, by  capillary attraction"
International  Convention declares that brazed joints are made above the melting point  of aluminium 610 degC. Below that temperature you are soldering. A  brazed joint is identified by the temperature of the filer metal, not by  the composition of the rod in the hand.
The  key words are by capillary attraction. Everything that you do, joint  design, fluxing, heating is aimed at promoting capillary flow. If this  is not done you are not brazing.'

Hence all the silver solders available, as well as the sifbronze alloys, are used to "braze" strictly speaking, but of course "silver soldering" is a term often used in practice,


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## Swifty (Apr 10, 2014)

I think that this discussion may go on for ever. I would like to give an example of a brazed joint, if we use some tubing, such as they use on bicycle frames, and attempt to braze one piece on to the other at 90deg. The joint is fully prepared, with the end of the tube sticking up machined to suit the radius of the base tube, we then braze relying on capillary action to draw the braze into the mating surfaces, with no excess braze on the outside. Job done, maybe, grab the top of the tube and apply a force, will the tube bend or the joint come apart, my feeling is that after a slight bend the joint will came apart.

We now repeat the same preparation, braze the joint making a nice fillet with the filler material, as you can do with correct brazing rod, and then do the same test trying to break the joint. My feeling here is that the joint will be much stronger due to the fillet adding a lot of support. With true silver solder it is almost impossible to get a fillet joint due to the solder wanting to flow and not sit there.

Paul.


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## TimTaylor (Apr 10, 2014)

Swifty said:


> I think that this discussion may go on for ever. I would like to give an example of a brazed joint, if we use some tubing, such as they use on bicycle frames, and attempt to braze one piece on to the other at 90deg. The joint is fully prepared, with the end of the tube sticking up machined to suit the radius of the base tube, we then braze relying on capillary action to draw the braze into the mating surfaces, with no excess braze on the outside. Job done, maybe, grab the top of the tube and apply a force, will the tube bend or the joint come apart, my feeling is that after a slight bend the joint will came apart.
> 
> We now repeat the same preparation, braze the joint making a nice fillet with the filler material, as you can do with correct brazing rod, and then do the same test trying to break the joint. My feeling here is that the joint will be much stronger due to the fillet adding a lot of support. With true silver solder it is almost impossible to get a fillet joint due to the solder wanting to flow and not sit there.
> 
> Paul.



Paul,

I don't disagree with what you said at all, but the O.P.'s original question was the difference between *SILVER* solder and *SILVER *brazing. 

You have introduced a 3rd process into the mix which is commonly referred to as braze welding or simply brazing, which uses an entirely different class of filler alloys that are primarily copper based, melt at much higher temperatures and have a much higher tensile strength, typically several orders of magnitude greater than the tin/silver alloys. The fillet buildup you describe is a characteristic of this process and adds strength to the joint. 

Tim


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## Swifty (Apr 11, 2014)

I see your point Tim, the confusion arises by what appears to me to be a modern term, silver brazing. When I worked for a living, we only had either silver solder of various silver content or brazing rods.

Paul.


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## OrangeAlpine (Apr 11, 2014)

robmort said:


> From the Cupalloys site:
> 'One definition in British Standards defines brazing as : "a  process of joining generally applied to metals in which, during or  after heating, molten filler is drawn into or retained in the space  between closely adjacent surfaces of the parts to be joined, by  capillary attraction"
> International  Convention declares that brazed joints are made above the melting point  of aluminium 610 degC. Below that temperature you are soldering. A  brazed joint is identified by the temperature of the filer metal, not by  the composition of the rod in the hand.
> The  key words are by capillary attraction. Everything that you do, joint  design, fluxing, heating is aimed at promoting capillary flow. If this  is not done you are not brazing.'
> ...


This makes no sense to me.  It states that in brazing, you do everything possible to promote capillary attraction and if this is not done, you are brazing.  

Or am I reading this wrong?

Bill


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## GWRdriver (Apr 11, 2014)

It appears this will be a case of irresolvable semantics, and a function of where you live, what you read in books and mags, who taught you, what name those around you called it, and what the local suppliers and sellers called it.   Here's a photo of a few of the silver solder containers I have, the majority of which are Harris and say "Silver solder"  like the middle one.  But the newer Harris packaging, as on the left, doesn't label it either way, cleverly dodging the issue!  The Silvaloy packet on the right does indeed call itself silver brazing alloy.  Yer pays yer money and yer takes yer choice.  I think the important thing for us (model builders) is to get the silver content right, meaning appropriate for the job at hand, and then you can call it whatever you like.


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## TimTaylor (Apr 11, 2014)

Swifty said:


> I see your point Tim, the confusion arises by what appears to me to be a modern term, silver brazing. When I worked for a living, we only had either silver solder of various silver content or brazing rods.
> 
> Paul.



I agree Paul, that's the way I learned it as well. 

This is only speculation on my part, but I suspect the term "silver brazing" may have come about as a way to differentiate the lower melting temperature silver solders, which can be used with conventional soldering irons, from the higher melting temperature silver alloys which would typically require a propane or butane torch to get enough heat.

Tim


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## robmort (Apr 11, 2014)

OrangeAlpine said:


> This makes no sense to me.  It states that in brazing, you do everything possible to promote capillary attraction and if this is not done, you are brazing.
> 
> Or am I reading this wrong?
> 
> Bill



You are indeed reading it wrongly. It clearly said 
"........if this is not done, you are not brazing"


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## GWRdriver (Apr 11, 2014)

TimTaylor said:


> This is only speculation on my part, but I suspect the term "silver brazing" may have come about as a way to differentiate the lower melting temperature silver solders, [snip]


Tim,
While it may only apply to a very small percentage of the population, even the steam model building population, I know it to be more than speculation and my first post ( #8 ) gives a good example of it.


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## Entropy455 (Apr 12, 2014)

GWRdriver said:


> It appears this will be a case of irresolvable semantics










Whats interesting is that when I search for the 76315 Harris part number, I find a brazing alloy  not a silver solder (see pic). Perhaps Harris labeled your package specifically for overseas sales?

For folks on these boards who require just a bit further clarification:

If you take a piece of 1/16 diameter Harris silver solder and wrap it around your hands & pull it apart  it will take about 25 pounds of force to break it (about 8,200 psi tensile strength - typical). If you take a piece of 1/16 diameter Harris silver braze and wrap it around your hands & pull it apart  it will take between 122 pounds to 214 pounds of force to break it  depending on the particular alloy (40,000 psi to 70,000 psi tensile strength typical).

And shear strength of a material is related to the ultimate tensile strength of the material. This means that if you assemble a copper boiler with silver solder the joints will be at a minimum of 5 times weaker in shear, than if you had used a proper silver brazing alloy. And when you take into account the fact that silver solder loses appreciable strength at elevated temperatures, your hobby boiler becomes a potential bomb while in operation. And for the record - Harris part number 76315 is in fact a silver brazing alloy, despite the "silver solder" labeling on the container that GWRdriver posted within a pic on page 2 of this thread.


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## OrangeAlpine (Apr 12, 2014)

robmort said:


> You are indeed reading it wrongly. It clearly said
> "........if this is not done, you are not brazing"


Well then, what are you doing?  Welding? Or perhaps, just screwing around?  

Certainly not soldering.  

Bill


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## GWRdriver (Apr 12, 2014)

Entropy455 said:


> If you take a piece of 1/16 diameter Harris silver solder and wrap it around your hands & pull it apart  it will take about 25 pounds of force to break it [snip] This means that if you assemble a copper boiler with silver solder [snip] your hobby boiler becomes a potential bomb while in operation.


Complete nonsense.


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## Entropy455 (Apr 12, 2014)

GWRdriver said:


> Complete nonsense.





In my profession, when you say that someone&#8217;s position is complete nonsense, it is customary to explain why. Let&#8217;s try something &#8211; I&#8217;ll post information, then you specifically identify and correct any nonsensical errors. Can you do that?

Cadmium-free 45% silver brazing alloy typically melts just under 1400 degrees F. A brazed butt-joint on copper with 45% silver, will typically have a joint tensile strength around 33,000 psi. A brazed butt-joint on brass with 45% sliver, will typically have a joint tensile strength of between 35,000 and 45,000 psi &#8211; depending on the brass alloy. Butt-joints are appreciably strong using this alloy, where the base material usually fails in lieu of the brazing alloy failing. Additionally, the increased shear-area of lapped-joints using 45% silver virtually guarantees that any joint failure will occur within the base material. A 100 psig hobby boiler (containing 338 degree F saturated steam) will be operating 1000 degrees less than the melting temperature of the brazing alloy.

Typical tin-silver soldering alloy (96/4) melts around 430 degrees F. A soldered butt-joint on copper or brass using &#8220;silver solder&#8221; will typically have a joint tensile strength under 14,000 psi. The tensile strength of the solder is less than that of brass and copper, thus the only way to achieve a strong joint is by utilizing very large lap-joints. A lap-joint using this alloy will achieve 11,000 psi shear strength (typical). A 100 psig hobby boiler (containing 338 degree F saturated steam) will be operating 92 degrees less than the melting temperature of the soldering alloy.


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## goldstar31 (Apr 12, 2014)

Perhaps a moderator could end what has been a nice balanced discussion but has now degenerated into something where the poster is probably being blinded with science. Unquestionably good joining has and will be carried out and which if safety is demanded, there will be boiler examiners and regular subsequent re-tests to ensure safety.

 Norman Atkinson


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## Entropy455 (Apr 12, 2014)

Goldstar31, do you really think its safe to construct a copper boiler, where the saturated steam temperature is only 92 degrees F away from melting the solder alloy?

I visit these boards as a hobby. I usually only browse, however Ill chime in whenever I see someone posting potentially dangerous advise.

This fall Im taking the final written examination required for obtaining my Professional Engineering License (the end of a tedious 8 year long process)  at which point Ill able to certify various engineering designs (including boiler design), in the interest of public safety, on behalf of the great State of Washington.

It's my business and obligation to dive deep into the science, which is why I take your criticism as a complement. . . .


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## GWRdriver (Apr 12, 2014)

Entropy455 said:


> Goldstar31, do you really think it&#8217;s safe to construct a copper boiler, where the saturated steam temperature is only 92 degrees F away from melting the solder alloy?


No one, not myself nor anyone else has even remotely suggested that this is in any way acceptable practice.  In fact just the opposite is true.  Continuing to muddle things simply to win the point is making this thread less educational, rather than more so.





> obtaining my Professional Engineering License (the end of a tedious 8 year long process) &#8211; at which point I&#8217;ll able to certify various engineering designs (including boiler design), in the interest of public safety, on behalf of the great State of Washington.


Now I see where this is coming from.  You should not make the mistake of assuming that no one save yourself knows anything about the science nor has an interest in the protecting the "health, safety, and welfare" of the general public (the way the US law usually reads.)  We do.  Another thing we know is that we never know who is reading what we write.  Responsible live steamers in every country go to great lengths to educate and self-police in order to preserve our 100% record of boiler safety.  When one individual, either uninformed or in search of notoriety, posts hyperbolic words such as "bomb" or "missile" or "shrapnel" in connection with model boilers I cringe because there's no telling who is reading those words.  If read by some misguided and overzealous official, this could put all our decades of good works in jeopardy.

BTW, there have been deaths associated with amateur live steam activities, all in the operation of "full size" equipment.  One incident that comes immediately to mind was the accidental release of steam from a vertical steam launch boiler which killed two in the UK.  The inquest found that the accident was caused during a certification inspection and steam test by the improper replacement of an inspection port gasket which was the responsibility of the "experienced" inspecting _*engineer*_.  Congratulations on soon obtaining your ticket (I got mine about 40 years ago.)  Hopefully you will come to see that it's power isn't in what you can to do TO other people, but in what you can do FOR other people.


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## Entropy455 (Apr 12, 2014)

GWRdriver said:


> Hopefully you will come to see that it's power isn't in what you can to do TO other people, but in what you can do FOR other people.



Why do you assume that Im seeking my professional engineering license for vengeful purposes? Thats such a strange and bizarre comment to make. Engineers use their stamp for profit. An engineer thats overbearing and unhelpful to his customers is going to lose business in a rapid fashion. I am curious as to why you, a licensed professional engineer, would identify himself as a retired architect. Which state did you get your stamp in? In which field of engineering did you obtain your degree? Or are we not talking about the same ticket?

On post 24, I commented that its unsafe to use silver-solder in constructing a copper boiler. Then on post 26 you said it was complete nonsense - which can only be inferred that you believe the opposite to be true. So which is it???


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## dnalot (Apr 12, 2014)

This is the sort of thing I don't come here for. Think I will take a week off.

Mark T


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## rick9345 (Apr 13, 2014)

one is an authority while being paid to testify(court of law)
rest of the time it is just an opinion
everyone has one
RESPECT


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## Hopper (Apr 13, 2014)

Getting back to the original topic, I think the solder/braze terminology may have varied over time as well as over geography.

My 1941 Machinery's Handbook refers to "hard-soldering" and "brazing" as interchangeable terms, but qualifies it by saying common useage is:
_"Brazing is generally understood to mean the joining of metals by a film of *brass*, wheras hard-soldering (used by jewellers) ordinarily means that "silver solder" is used. (see silver solders)"_

The referred to section on silver solder then goes on to say silver solder is a hard solder used by jewellers and electrical manufacturers and has a silver content in various instances from 49 per cent to 70 per cent. 
Quote:_ "Silver coins can also be used for small work.
..."Silver soldering is employed for uniting comparatively small parts requiring a strong joint."_

Then in the section on brazing, it says _"The alloys used for brazing are composed of copper-zinc alloys. "_
No mention of silver in relation to brazing.

So 50 to 70 per cent silver rods were considered "Silver Solder", in 1941, in the US published Machinery's Handbook.

This was the same thing I was taught both on the job and at trade school as an apprentice in the 1970s in Australia and used all through my working life in the trades here, Africa and the US.

Seems though that today at the local Australian hardware stores, they have labelled "silver brazing" rods of 50 per cent silver etc, and "silver solder" that is 3 or 5 per cent silver and the rest tin. Seems to have been something that came about with the mandate to remove lead from plumber's solder.


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## Entropy455 (Apr 13, 2014)

The mainstreaming of tin-silver solder was likely a result of the anti-lead movement. Adding further confusion into the mix, is the advent of lead-tin-silver solder (also called silver solder), which is intended to increase electrical conductivity within high-fidelity electronic circuits.

Silver brazed piping joints are to this day widely used in business and industry within low to medium pressure applications. The joints are relatively easy to makeup (no fancy welding equipment), and more importantly, the joints can be disassembled and reassembled without grinding out welds. The high strength of a brazed joint hinges solely on the shear-strength of the brazing alloy. Inadvertently putting silver-solder into a joint that&#8217;s holding back 300 degree F pressurized water, or pressurized ammonia, or pressurized gasoline, is a very serious accident waiting to happen. If one were to dive into the historical chapters of ASTMs and the BPVC, I&#8217;m sure they&#8217;d find references to case-studies where people have died from the use of silver solder within joints intended for use with silver-braze &#8211; as there&#8217;s a reason why our technical books and references have been rewritten to specifically distinguish between soldering and brazing.

Silver-Tin solder has its place within low-pressure and low-temperature joints, such as potable water copper pipes, open-ended drain and collection piping, and possibly within some HVAC applications also.

Lead-Tin-Silver "silver-solder" belongs on transistor leads.

Silver-Solder alloys have no business whatsoever within high-energy steam joints.


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## GWRdriver (Apr 13, 2014)

Ripcrow said:


> [snip]also I notice little gas bubbles in one of my failed welds


In all the hubbub I don't see your question about this answered and I can shed some light on that for you.   If by _welds_ you mean silver-soldered joints, with high silver content silver solders bubbling indicates the solder has boiled and that is always the fingerprint of overheating.
Typically overheating arises for one of two reasons, the first being the torch has accidentally been allowed to linger for too long in one place and isolated overheating occurs.  The second is very often the result of poor joint preparation, ie, fitting, cleaning and fluxing, or perhaps even the wrong flux, or contamination of the work prior to heating. When you are up to the temperature at which the solder should flash into the joint, but the joint rejects the solder, a common response is to pour more heat into it and hope for the best.
This rarely solves the problem and in fact usually makes matters worse, typically by causing the formation of oxides and/or burning the flux.  This can lead to an array of difficult problems, some fatal to the work, such as contaminating joint which can no longer be reached to clean and re-prepare.  That is why so much emphasis is placed on joint preparation.


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## Ripcrow (Apr 16, 2014)

Well this is generating a fair amount of debate. At least I'm confused for a reason,you would think that there would be common terms used around the world in engineering .thanks for all your replies


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## pacomb (Apr 24, 2014)

Hello all, I enclose a link to my blog where I have a video explaining silver soldering that might help many

http://www.ahsprite-mk3-restoration.blogspot.com.es/2012/11/six-steps-of-successful-brazing.html


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## goldstar31 (Apr 24, 2014)

pacomb said:


> Hello all, I enclose a link to my blog where I have a video explaining silver soldering that might help many
> 
> http://www.ahsprite-mk3-restoration.blogspot.com.es/2012/11/six-steps-of-successful-brazing.html


 
 I can understand silver soldering and whatever. I was a certified welder and all that. Again, I have double distinctions in City and Guilds in Motor Vehicle Restoration and trained with the Nissan crowd from Washington, County Durham and have had a Spanish registered car which is due for another ITV this year. I built and restored MiniCoopers, Spridgets, MGB and C's and well, a lot of things. So my questions are valid?

 As Spridgets were built with a sort of chassis like the Spits, they were constructed mainly with spot welding- so that they would tear and probably absorb some shock in a collision. Of course, this was before Thatcham and actually counting the specified  number of welds in a section in a repair. Certainly, continuous seam welds using the Mig/Mag process have always been frowned on. 

 How does the ITV in Spain and the appropriate Spanish  vehicle insurers regard the rather unusual structural welding system which you appear to have adopted.

 Regards,

 Norman


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## Hopper (Apr 26, 2014)

Entropy455 said:


> ...If one were to dive into the historical chapters of ASTMs and the BPVC, Im sure theyd find references to case-studies where people have died from the use of silver solder within joints intended for use with silver-braze  as theres a reason why our technical books and references have been rewritten to specifically distinguish between soldering and brazing.
> .



Ah yes, now that makes a lot of sense. Never was a problem in the old days before this newfangled 5 per cent silver solder stuff existed. But certainly could lead to deadly confusion today.


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## robcas631 (Apr 28, 2014)

Norman,

In the UK do you also call it "sweating?" My family came from the UK and we still use the same words/ slang you do.


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## robcas631 (Apr 28, 2014)

No doubt this is a heated debate. :wall:


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## barnesrickw (Apr 29, 2014)

Sweating is a reference to soldiered copper tubing 'round here.  


Sent from my iPad using Model Engines


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## pacomb (Apr 29, 2014)

goldstar31 said:


> How does the ITV in Spain and the appropriate Spanish vehicle insurers regard the rather unusual structural welding system which you appear to have adopted.


 
Hello Norman, 

Where have I said that I have adopted the silver brazing system to make repairs on my car?

No, lets see, I added the link on my site, because I found the video very useful to understand the procedure of making a good silver welding. Also because " maybe some parts" in a restoration can be soldered with silver soldering. Lets face it, people that restore cars, are like minded people, and do tend to make many other handcrafts, and silver welding is always welcome. That is why I though it would be useful. 

And because people in this thread where talking about it, though many will enjoy the video as I did.

ITV or MOT dont check weldings. They check the overall safety of a car, if it has play on the axels, if brakes are ok, no fuel leaks, etc. If you have used one soldering system or an other, no one is going to check it.


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## Tater (Apr 29, 2014)

http://en.wikipedia.org/wiki/Brazing


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