soldering 430 stainless (maple syrup pans)

[markct]

i have recently gotten a maple syrup evaporator that has pans of soldered stainless construction, the tag on the pan says the material is 430, they have a few places that need minor repair. they also have brass fittings on them that are a weird taper fit rather than threaded, i would like to solder on stainless pipe nipples in a few of these places. what i dont know is much about soldering stainless, they are done with a soft solder, not silver solder. will this soft solder stick to most any stainless, like if i use a 304 fitting or nipple will it adhere ok? also is there any reason not to use silver solder, in places where it wasnt previously soldered with soft solder i mean. also what type of flux is best to use, most of the usual plumbing solder flux says not for stainless.

[Ironman]

A silver solder will work well. For a small job most hardware stores will have a Bernz-o-Matic product called "stainless brazing rods" They are blue colored and seem to be flux coated silver solder.

[GWIZ]

I've soldered alot of electrical things using lead based solders without any problems.
Copper, brass and steel.

I never could solder to stainless.
After your post and finding this link I decided to give it a try.
http://www.azom.com/details.asp?ArticleID=1178

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Two SS non-magnetic washers.
Before soldering I sanded just the area that I wanted the solder to adhere to.

I first tried it with standard rosin flux and rosin core solder. Did not work.
The stainless cools off the flux and it just burns and contaminates the SS. the flux did not flow like it does on copper when heated.

The black spots on the larger washer is the burnt rosin flux.

===
I switched to a solid core solder 60/40 (no flux inside) and some water based flux.(don't know what type, I got it from a swapmeet).
This worked good and the bond is good, roughing the surface up with sand paper is a must.
Notice the smaller washer, the water based flux did not burn like the rosin flux.
If the SS starts to discolor from heat the bond is not going to be very good and you will need to sand the area again.

Its going to be a fine line. the slightest overheating will oxidize the SS and you will not get the solder to stick, at that point you need to clean it again.
Maybe a flux made specifically for SS will give a better temperature range, otherwise if you don't have any experience with soldering its going to be hell.

===
Before joining the pieces together sand and coat each of the pieces with solder first.

If this is for making food or something you will need to find out what filler is safe to use. maybe lead free solder or a 5% silver/tin solder low temp.
that also goes with silver-solder.

Silver-solder would be better, but you will need to remove all the old soft solder otherwise it will burn and give you problems..
A problem that you may run into with silver-solder is the heat spreading over and melting other low temperature joints.

[storts]

I use a flux by mcmaster carr,or torry s crane co,in southington,ct. Has to be acid based,as i make alot of lead heating anf cooling coils,that have to have ss nipples,so I just wire brush the ss nipple,and there all 316l, and flux it and us a 50/50 bar tin,works great,also works on inconel, monel,i might even have a little left,for the lead annodes I make,I have to tin the steel,and use ruby red from mcmaster,like 14 bucks a gallon,,Let me check to see if its good for stainless,and you are using 400 series! So should be easy! Mcmaster has a stainless steel soldering flux,, 1/2 # jar $9.93 in both a white and black,,Page # 3161 in the cat#111 edition! part # 7693A1 or A2,,Good luck,i use my lead burning outfit,as I can control the heat,Ive also Tiged it also!!!,Jack
PS ----Mcmaster has no min,so if ya need a 25 cent screw,you got it!!!

[markct]

well i need to stick with soft solder since thats what is already on the pans, but i look in mcmasterr carr and the only stainless flux i see that doesnt say for silver solder is this stuff,
Stainless Steel Soldering Flux

Fast-acting liquid acid flux for most grades of stainless steel, as well as chrome, copper, and brass. Use with all types of soft solder. Meets Fed. Spec. O-F-506C, Type II and A-A-51145C, Type IIB and is ROHS compliant. Note : Not for use on stainless steel water tubing.


so since it says not for use one stainless steel water tubing i take it to mean its not foodsafe so thats not gona work for maple syrup! this is a bit of a problem, the maple equipment dealer sells lead free solder for stainless and the flux to go with it, but for a long time now they have been outa the flux and dont know when they will be able to get more, and they dont know exactly what is was either the lady said, no brand or trade name etc.

[Ironman]

Hi GWIZ
The stuff I was referring to is here. http://www.bernzomatic.com/bernzomat...ernzoCat100061
They call it NS3 - 85,000 PSI tensile strength, 1250F to 1750F working temperature
It actually is a brazing material, and on the package I have they say it is for stainless. I have used it for repair of the 4130 tubing used in hydraulic systems, and for stainless tubing.
I melted gold one time in one of my wife's bowls as it isn't supposed to bond to it. Let me tell you, it was a great solder and she wanted me to get her another bowl.

[storts]

Originally Posted by markct

well i need to stick with soft solder since thats what is already on the pans, but i look in mcmasterr carr and the only stainless flux i see that doesnt say for silver solder is this stuff,
Stainless Steel Soldering Flux

Fast-acting liquid acid flux for most grades of stainless steel, as well as chrome, copper, and brass. Use with all types of soft solder. Meets Fed. Spec. O-F-506C, Type II and A-A-51145C, Type IIB and is ROHS compliant. Note : Not for use on stainless steel water tubing.


so since it says not for use one stainless steel water tubing i take it to mean its not foodsafe so thats not gona work for maple syrup! this is a bit of a problem, the maple equipment dealer sells lead free solder for stainless and the flux to go with it, but for a long time now they have been outa the flux and dont know when they will be able to get more, and they dont know exactly what is was either the lady said, no brand or trade name etc.

I take it as no presure as in water piping,Thats a fda spec,thats in there,Your fixing pans,Not pressure piping,correct? Thanks,Jack