Lower melting temp cadmium free solders for boilers

This forum is dedicated to the Live Steam Hobbyist Community.

Moderators: cbrew, Harold_V

Post Reply
dorin
Posts: 606
Joined: Thu Nov 28, 2002 5:24 am

Lower melting temp cadmium free solders for boilers

Post by dorin »

I have a question from a friend of mine.
The old construction series suggest solders with cadmium for soldering at lower temperatures.
If one wanted a lower temperature solder, for a boiler, which did not contain cadmium, what choices are out there?
Thank you,
Mike
www.chaski.com
User avatar
Bill Shields
Posts: 10459
Joined: Fri Dec 21, 2007 4:57 am
Location: 39.367, -75.765
Contact:

Re: Lower melting temp cadmium free solders for boilers

Post by Bill Shields »

Safety silv from Harris.

It is not a cadmium thing with temp was much as it is silver percentage.
Too many things going on to bother listing them.
dorin
Posts: 606
Joined: Thu Nov 28, 2002 5:24 am

Re: Lower melting temp cadmium free solders for boilers

Post by dorin »

Thank you, Bill!
I just got a message asking about this stuff.Forney 38116
https://www.amazon.com/Gen-Rep-Silver-S ... B000PSB6KU

Can it be true that it has a working temperature up to 1,100 degrees but melts at 400 to 700??
How could that be??
www.chaski.com
User avatar
Builder01
Posts: 726
Joined: Mon May 18, 2015 5:26 am
Location: Erie, PA

Re: Lower melting temp cadmium free solders for boilers

Post by Builder01 »

That solder from Amazon is only 6 per cent silver solder. You need around 45 per cent silver for making boilers. 6 per cent silver solder is not fit for making a boiler.
User avatar
Bill Shields
Posts: 10459
Joined: Fri Dec 21, 2007 4:57 am
Location: 39.367, -75.765
Contact:

Re: Lower melting temp cadmium free solders for boilers

Post by Bill Shields »

Ditto...that is pipe fitter's stuff...not boiler maker's

I use anywhere from 25% or up for my boilers.

You are not going to get away cheap building a proper, safe boiler.
Too many things going on to bother listing them.
dorin
Posts: 606
Joined: Thu Nov 28, 2002 5:24 am

Re: Lower melting temp cadmium free solders for boilers

Post by dorin »

Thank you, guys!
I don't think he is trying to save money. I think he is trying to fix a leaky stay-bolt on a large copper boiler.
When he heated it up enough for the first bolt, another bolt started to leak.
www.chaski.com
User avatar
Bill Shields
Posts: 10459
Joined: Fri Dec 21, 2007 4:57 am
Location: 39.367, -75.765
Contact:

Re: Lower melting temp cadmium free solders for boilers

Post by Bill Shields »

Welcome to world of boilermaking
Too many things going on to bother listing them.
User avatar
Builder01
Posts: 726
Joined: Mon May 18, 2015 5:26 am
Location: Erie, PA

Re: Lower melting temp cadmium free solders for boilers

Post by Builder01 »

Yes, this happens quite frequently. You must cover everything with flux including areas that have already been silver soldered. Even when this is done, you can still create leaks in areas previously soldered. Staybolts are particularly problematic as they are in close proximity to each other an there is not a good way to isolate the heat to a single stay bolt. Plate flanges are much easier to fix, but, seldom leak anyway. I think what happens, is during a reheat, some of the alloy in the silver solder is boiled away and can create a pinhole leak, very anoying!!!

Sometimes, these very small leaks will go away when the boiler is fired, as the minute voids in the silver solder become filled with impurities in the water. Also, these sorts of minute leaks can be stopped with some very gentle massaging with a center punch, or, nail set.
User avatar
gwrdriver
Posts: 3439
Joined: Mon Jan 06, 2003 10:31 am
Location: Nashville Tennessee

Re: Lower melting temp cadmium free solders for boilers

Post by gwrdriver »

If I had $5 . . . (it used be 5¢, but things have gone up) for every time I had to answer that question! Somewhere on the packaging or product description it should say, and used to say, "silver-bearing" solder, but maybe not any more. It's worthless for building a boiler UNLESS you were to go old-school and build it riveted or screwed throughout and used the silver-bearing solder as caulk. But that's very old-school, now obsolete practice, and such a boiler would be highly suspect nowadays.

The silver-bearing solder could be used as one would common tin-lead solder to caulk a weep, accepted practice, however once applied to a boiler that spot or area could never be silver-soldered again unless every molecular trace of the tin-lead solder was removed.
GWRdriver
Nashville TN
dorin
Posts: 606
Joined: Thu Nov 28, 2002 5:24 am

Re: Lower melting temp cadmium free solders for boilers

Post by dorin »

Wow, some very interesting answers.
I will let him know.
www.chaski.com
User avatar
gwrdriver
Posts: 3439
Joined: Mon Jan 06, 2003 10:31 am
Location: Nashville Tennessee

Re: Lower melting temp cadmium free solders for boilers

Post by gwrdriver »

Indeed! How could that be?
I just looked at the description of the referenced solder and found parts of it misleading, at best, if not downright deceptive.

"Working temperature up to 1,100°F" - What do they mean by Working temperature? That it will "work" at up to 1100°F? We think not.
"Application temperature is 400° F" - If by this they mean the liquidus, the melting temperature, at which point it can be applied to the work, they aren't far off.

Difficult to resist for the uninformed but eternally hopeful new boiler builder.
GWRdriver
Nashville TN
User avatar
Harold_V
Posts: 20231
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Lower melting temp cadmium free solders for boilers

Post by Harold_V »

I can't help but wonder if, maybe, the 1,100°F temperature implies that the solder won't degrade below that temperature. Oxidation is a problem with most molten metals.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
Post Reply