silversolder question

[1930artdeco]

I am going to start practice silver soldering some copper pipes for my Air Compressor this weekend. My questions are these:

1) I have seen videos of two different styles of soldering. One video will show the normal heat and the solder will wick into the joint.
2) I have seen another video where the do the usual soldering and then they adda large 'crown' I think is what they called it on top of the regular solder.

Which one should I do? Besides there not bring a leak am I good with the normal solder amount? Do I need the 'crown' due to 100 lbs of pressure?

Thanks,

Mike

 

[GrayFlattop]

Soldering or silver brazing?

Take a look at CDA publication A4015-14/20 table 14.4a for the appropriate pressure-temperature ratings of soldered joints.

Assuming appropriate cleaning and preparation, you are probably overthinking it.

 

[no704]

Normal plumbing solder will work fine and is much easier than silver. Flows at a much lower temperature.

 

[1930artdeco]

After reading through the book, if I read the chart correctly, I should be able to use 95-5 Tin/Antimony solder (TABLE 14.4a. Pressure-Temperature Ratings of Soldered and Brazed Joints). It says, the joint can get up to 250 F and its burst pressure is 270 PSI. My tank tops out at 140 PSI and I will operate it at 100 PSI. So I should be safe to solder and not braze. I will probably use the silver as I have it on hand already.

 

[no704]

Silver solder is substantially more difficult to work with and will require at least mapp/oxy rig to do efficiently. Regular 60/40 is much easier and can be done with a regular propane torch. And is much less expensive. Plenty good for compressor lines.
Silver solder is great stuff, but way overkill for this application. Best of luck on your project!

 

[no704]

After reading through the book, if I read the chart correctly, I should be able to use 95-5 Tin/Antimony solder (TABLE 14.4a. Pressure-Temperature Ratings of Soldered and Brazed Joints). It says, the joint can get up to 250 F and its burst pressure is 270 PSI. My tank tops out at 140 PSI and I will operate it at 100 PSI. So I should be safe to solder and not braze. I will probably use the silver as I have it on hand already.

It’s good for high pressure refrigeration lines. Getting the copper hot enough for it to flow is not far from melting the copper itself.

 

[danski0224]

It’s good for high pressure refrigeration lines. Getting the copper hot enough for it to flow is not far from melting the copper itself.

You are describing brazing.

A silver bearing solder like StaBrite 8 has a fluid temperature that is approximately 100° F higher than 95/5 solder (IIRC, I'm not looking up the specs). Way less heat than brazing.

 

[danski0224]

Silver solder is substantially more difficult to work with and will require at least mapp/oxy rig to do efficiently.

Um, no.

 

[danski0224]

Normal plumbing solder will work fine and is much easier than silver.

StaBrite 8 has a much wider plastic range than the typical plumbing solder. I believe it is called the "liquidus" range. This property makes silver bearing solder much more useful and it can be used with greater control.

Harris "Bridgit" is the only non-silver bearing solder I have used that has some of the same properties as StaBrite 8, which means that it can fill some gaps more easily than some of the other products out there.

Flows at a much lower temperature.

There isn't much of a difference between 95/5 and StaBrite 8.

 

[danski0224]

I am going to start practice silver soldering some copper pipes for my Air Compressor this weekend. My questions are these:

Silver bearing solder or brazing? These are not the same, although many use the terms "soldering" and "brazing" interchangeably.

You will be able to silver solder with a plain old propane torch. Brazing requires much more heat, such as an air-acetylene torch.

You will want a real torch head, like a Turbo Torch STK-99. Much better than the Bernz O Matic or Weller stuff at the box stores.

1) I have seen videos of two different styles of soldering. One video will show the normal heat and the solder will wick into the joint.
2) I have seen another video where the do the usual soldering and then they adda large 'crown' I think is what they called it on top of the regular solder.

Which one should I do? Besides there not bring a leak am I good with the normal solder amount? Do I need the 'crown' due to 100 lbs of pressure?

You do not need to cap the joint.

If you use a product with a wide plastic range, you will be able to flow a little extra and it will sit on top. StaBrite 8 and Harris "Bridgit" have a wide plastic ("liquidus") range.

 

[OccupantRJ]

Silver solder and brazing as a process and materials seems to have a life of it’s own when discussed. We used a wire form of silver solder at work to mechanically connect two pieces of brass that was $18 per troy ounce and that was ten years ago. A coil of it was around $1,800 then. The price would likely wake you up now.
I have a friend who calls lead type solder silver solder because his brain locks in on the color and no amount of persuasion convinces his country *** otherwise.

 

[housewolf]

I am going to start practice silver soldering some copper pipes for my Air Compressor this weekend. My questions are these:

1) I have seen videos of two different styles of soldering. One video will show the normal heat and the solder will wick into the joint.
2) I have seen another video where the do the usual soldering and then they adda large 'crown' I think is what they called it on top of the regular solder.

Which one should I do? Besides there not bring a leak am I good with the normal solder amount? Do I need the 'crown' due to 100 lbs of pressure?

Thanks,

Mike

It isn’t necessary to “cap” the joint. During a medical gas shutdown, sometimes we might cap a joint if there’s any doubt we may not have gotten it good. Last thing we’d want is to do the shutdown twice because we had a leak. If you’re in a situation where it would be a great inconvenience to repair a leak, sure, cap it. Silver solder is strong enough just a cap will hold more pressure than the pipe.

If you’re taking a med gas installer test in TX, they DGAF about a cap. They cut a strip longways down the joint, polish it, and you won’t pass if they see a void anywhere between the pipe and fitting.

Keep in mind it will be annealed (soft) when you’re finished and it won’t look as nice.

 

[MoonRise]

Brazing is joining pieces with a filler that melts above 840F but below the melting point of any of the workpieces and the filler flows into the joint via capillary action.

Soldering is the same except that the filler melts below 840F.

Harris Stay-Brite silver solder has a melting temp (singular, as it is a eutecic alloy) of 430F, Stay-Brite8 liquidus is 535F, and Bridgit is 630F. 95-5 lead free solder is 465F.

Depending on the size/diameter and material(s), soldering can usually be done with an air-propane torch. Actual MAPP gas is no longer available, but used to give both some more heat and a little higher temperature than propane with an appropriate air-fuel torch. The new 'map' is just propylene, only about 10% more heat and temperature than propane at ~3x the price. Bleh.

Moving up you can get air-acetylene torches and then on to oxy-fuel torches.

Harris (and other companies) have multiple brazing fillers, both silver containing and non-silver for different purposes.

As to the OP, soldering with 95-5 or with a silver solder may be sufficient on copper pipes for compressed air.

Brazing would be another option. A self-fluxing brazing alloy like a copper phosphorus one would be a good choice.

If using Flux (psst, you. NEED to use Flux when soldering) how do you plan to remove the Flux from the air lines? When soldering water lines, the water flushes out the Flux. Air is not going to remove the Flux residue from inside the pipes.

 

[danski0224]

We used a wire form of silver solder at work to mechanically connect two pieces of brass that was $18 per troy ounce and that was ten years ago.

Probably 45, 50 or 56% silver alloy.

Harris Safety-Silv 45 1/16" x 1 toz High Silver Brazing Alloy 4531

Buy Harris Safety-Silv 45 1/16" x 1 toz High Silver Brazing Alloy 4531 today at the lowest prices anywhere. Fast, free shipping. Get yours now!

harrisweldingsupplies.com

 

[danski0224]

Brazing would be another option. A self-fluxing brazing alloy like a copper phosphorus one would be a good choice.

And then there should be a nitrogen purge to keep the black oxide stuff from forming inside the piping during the brazing process. Which then flakes off.

If using Flux (psst, you. NEED to use Flux when soldering) how do you plan to remove the Flux from the air lines? When soldering water lines, the water flushes out the Flux. Air is not going to remove the Flux residue from inside the pipes.

Not sure this is a huge issue IF the flux is applied properly. Just a little bit is needed.

 

[BillK]

Like the others have said, Silver Solder is a pain to work with even after you get used to it. All of the copper air lines in my shop were done with a propane torch and old school plumbing solder. My compressor is set at 160 lbs and they have been fine for 25 years of daily use.

You are overthinking it.

 

[PWC Repair]

Silver bearing solder or brazing? These are not the same, although many use the terms "soldering" and "brazing" interchangeably.

You will be able to silver solder with a plain old propane torch. Brazing requires much more heat, such as an air-acetylene torch.

You will want a real torch head, like a Turbo Torch STK-99. Much better than the Bernz O Matic or Weller stuff at the box stores.

You do not need to cap the joint.

If you use a product with a wide plastic range, you will be able to flow a little extra and it will sit on top. StaBrite 8 and Harris "Bridgit" have a wide plastic ("liquidus") range.

This guy has great answers. The Harris brand "Stay Brite" "Bridgit" are great products that flow out nicely at lower temps. If you have 6-15% silver solder sticks you will get frustrated quickly without an oxy/acetylene torch setup.

 

[1930artdeco]

OK, first of all thank you all for the education and comments. Second of all, I may have gone down the wrong road with what I purchased. I didn't have the knowledge at the time-oh well, I am learning. It will work but after reading the copper manual I believe like others have said it is overkill. I bought from Harris some Safety-Silv 56 and their Stay-Silv flux.

Right now I have the standard Benzo-Matic propane torch and some fake MAPP gas. So....since the silver alloy melts at 1205 and propane burns hotter than that I will use the silver up and then get some 95-5 solder. Can I still use the same flux with standard solder?

MOONRISE-as to washing out the flux residue. I plan on brazing/soldering off unit for all of it except when I hook everything together. The ones done off unit I can flush with water and then let dry before I hook them up. After the hook up not sure how to get the residue out. I might be able to flush the in garage part with water and then let it dry. I will have to think on that.

 

[danski0224]

get some 95-5 solder. Can I still use the same flux with standard solder?

Yes. Get Harris Bridgit.

 

[1930artdeco]

DANSKI-since I will stick to soldering I hope the black oxide won't form as much. And yes I just plan to use a tiny bit of flux per the manual. I will see if I can return the stuff I bought to Harris.

Mike

 

[PWC Repair]

OK, first of all thank you all for the education and comments. Second of all, I may have gone down the wrong road with what I purchased. I didn't have the knowledge at the time-oh well, I am learning. It will work but after reading the copper manual I believe like others have said it is overkill. I bought from Harris some Safety-Silv 56 and their Stay-Silv flux.

Right now I have the standard Benzo-Matic propane torch and some fake MAPP gas. So....since the silver alloy melts at 1205 and propane burns hotter than that I will use the silver up and then get some 95-5 solder. Can I still use the same flux with standard solder?

MOONRISE-as to washing out the flux residue. I plan on brazing/soldering off unit for all of it except when I hook everything together. The ones done off unit I can flush with water and then let dry before I hook them up. After the hook up not sure how to get the residue out. I might be able to flush the in garage part with water and then let it dry. I will have to think on that.

That's 56% silver for brazing steel to copper like a heat exchanger plate or compressor with steel fittings.........huge commercial stuff. Yes, regular propane burns hotter but I promise you'll likely NEVER get any silver solder melted in nice on a copper line without AT LEAST MAPP gas. Been there, tried that. The copper keeps wicking away the heat faster than the propane can dish it out.

 

[danski0224]

the black oxide won't form as much.

For regular soldering, you will not get any black oxide. At all.

 

[danski0224]

NEVER get any silver solder melted in nice on a copper line without AT LEAST MAPP gas.

Well, what they call MAPP gas today is only a hundred or so degrees hotter than plain propane, IIRC.

 

[rooster59]

I am going to start practice silver soldering some copper pipes for my Air Compressor this weekend. My questions are these:

1) I have seen videos of two different styles of soldering. One video will show the normal heat and the solder will wick into the joint.
2) I have seen another video where the do the usual soldering and then they adda large 'crown' I think is what they called it on top of the regular solder.

Which one should I do? Besides there not bring a leak am I good with the normal solder amount? Do I need the 'crown' due to 100 lbs of pressure?

Thanks,

Mike

 

[MoonRise]

And then there should be a nitrogen purge to keep the black oxide stuff from forming inside the piping during the brazing process. Which then flakes off.

Not sure this is a huge issue IF the flux is applied properly. Just a little bit is needed.

Facepalm.

Oof. I know that piping / tubing usually has to be purged before brazing or welding (stainless, I'm looking at you). Forgot to write it up for him.

Well, what they call MAPP gas today is only a hundred or so degrees hotter than plain propane, IIRC.

Yup, that aspect I did mention. The 'new' map/PRO stuff isn't MAPP, it's just propylene. At ~3x the price of propane. Actual MAPP is no longer available, unless you find some old stock somewhere (garage sale).

 

[danski0224]

A "professional" torch head like I mentioned above makes a huge difference. Much better than the ones at the box stores.

No issues doing 1" cast bronze plumbing valves with plain old disposable propane cylinders.

 

[Beerhippie]

When I first started at the brewery, CO2 was run at 300psi in the mains. We used plain old 95/5 Sn/Sb plumber's solder. Never had a problem. Same lines are still in use at a much more sane 125psi--27 years later.

 

[nadogail]

Because Potable (Drinking) Water is not involved I would use a 50/50, 60/40 or 63/37 Tin Lead Solder with Acid Flux.

I like the way Tin Lead solder wets and flows.

 

[T444e]

Because Potable (Drinking) Water is not involved I would use a 50/50, 60/40 or 63/37 Tin Lead Solder with Acid Flux.

I like the way Tin Lead solder wets and flows.

Why buy a roll of solder for one project that cannot be used on domestic water? I'm sure he will not use an entire roll and will have it laying around. Lead free solder can be used in more applications.

My compressed air is sweat copper, all the joints done with Canfield 100% Watersafe solder, except two. This is the only solder I use. I brazed two joints (Sil-Fos 15) on my system, steam coil for an aftercooler, didn't care for the fit up and preferred a joint I could put a cap on.

 

[nadogail]

Why buy a roll of solder for one project that cannot be used on domestic water? I'm sure he will not use an entire roll and will have it laying around. Lead free solder can be used in more applications.

My compressed air is sweat copper, all the joints done with Canfield 100% Watersafe solder, except two. This is the only solder I use. I brazed two joints (Sil-Fos 15) on my system, steam coil for an aftercooler, didn't care for the fit up and preferred a joint I could put a cap on.

Almost all of my soldering is for Electrical or Mechanical purposes, I try not to solder Potable Water systems. I grew up with Lead Pipes and I m not afraid that my exposure to Lead has stunted my mental capacities. I also rode bicycles without helmets as a child and drank from Garden Hoses.

 

[ipgenie]

About 10 years ago I installed some solar collectors to heat the tank for my in floor heat at my home. We used silver solder due to the potential for high pressure in the case of system failure causing the antifreeze to flash to steam.
Two MAPP torches were not enough because the large copper manifolds just drew the heat right away from the joint. We ended up bringing my oxy acedeline torch up on the roof to do the job.
I would return the silver solder if possible and get regular solder for this job. I would still have most of the silver roll on my shelf all these years later if I didn't have a guy helping me who already had some. I've never needed it for anything since.

 

[Milton Shaw]

The choice for copper to copper was 15% silver Sil-Flos with no flux and really didn't have to clean (sand) the joint. For Steel to copper the choice was 45% wire silver solder with flux and clean (sand both ends. I used a air/ acetylene torch which gives a 4500 degree temp that is adequate for copper to copper and steel to copper brazing. I didn't need a oxygen tank to get the temps to do this with. A Turbo torch was adequate and didn't need to carry the duplex hose, oxy tank and regulator to carry as extra weight. This was mostly cap tube, 1/4. and 5/16 refrigerator tubing not 7/8 and 1 1/4 inch air conditioner tubing. We used epoxy for copper to aluminum joints on room air conditioners and PTAC joints.

 

[Fabtechprerunner]

And then there should be a nitrogen purge to keep the black oxide stuff from forming inside the piping during the brazing process. Which then flakes off.

Not sure this is a huge issue IF the flux is applied properly. Just a little bit is needed.

Always always flow nitrogen, 5psi flow.
Purge the lines after flowing and soldering to remove any moisture or oxygen that resides inside the lines.

You will still accumulate oxidation and Cuperic Oxide on the outside of the copper at both the condenser and coil, and that is normal. However, you will NOT develop/form Cuperic Oxide (oxidation) or black scale on the inner wall of the copper line set. Remember to remove you valve cores when flowing nitrogen. When you begin flowing, give it a few minutes to allow the nitrogen to flow from your high side (high pressure side) through the line set, through coil and back to the condenser low side (suction side).

Then vacuum the system, followed by purging the lines and breaking vacuum, purge again, vacuum and purge again and vacuum. You want to remove any and all residual moisture and oxygen out of the lines.

If you dont purge and break vacuum, you will sit there forever waiting to try and remove non-condensables.

 

[ching0n]

I am going to start practice silver soldering some copper pipes for my Air Compressor this weekend. My questions are these:

1) I have seen videos of two different styles of soldering. One video will show the normal heat and the solder will wick into the joint.
2) I have seen another video where the do the usual soldering and then they adda large 'crown' I think is what they called it on top of the regular solder.

Which one should I do? Besides there not bring a leak am I good with the normal solder amount? Do I need the 'crown' due to 100 lbs of pressure?

Thanks,

Mike

It's been a long time since I've done it but I don't remember being able to 'build up' silver solder like that. I did w/some HVAC silfos that works at high temperatures though. Look up some silversmithing/jewelry videos, they're masters w/that stuff.

 

[ching0n]

If t his is just an air comp. application, I wouldn't worry about purging since you won't be cycling the contaminants through the compressor. Then again, brazing would be way overkill for conventional pressures (I'd just use plumbing stuff):

 

[Firebrick43]

'silver soldering' as conventionally known (term of art) is indeed brazing.....this is different than soldering w/a lead compound.

Staybrite 8 like Danski mentioned contains silver and doesn’t have lead in it.

Before lead free solders became a thing silver soldering was nearly always a form of brazing but in the last 2 decades silver bearing true solders have become more and more popular and there fore confusing a lot of people that don’t realize the messed up vernacular from the a previous century.

 

[ching0n]

Staybrite 8 like Danski mentioned contains silver and doesn’t have lead in it.

Before lead free solders became a thing silver soldering was nearly always a form of brazing but in the last 2 decades silver bearing true solders have become more and more popular and there fore confusing a lot of people that don’t realize the messed up vernacular from the a previous century.

I went to google and I edited my post since there's some definitions around melting temperature and didn't want to mislead.

 

[LopezBart]

Note that a joint properly prepared for silver brazing with 40-60% alloys has about .003" clearance; for smaller joints very little solder is needed. Such silver brazing is much stronger ( 30KSI shear ) and much more resistant to both vibration and creep. The surfaces should be cleaned w/ alcohol and then HCL. A fluoride-containing flux seems to work best for me.

The boiler in our small steamboat (about 15 sq ft of heating surface) has 55 1/2" copper coils soldered into steel ******* that are welded into the drum; the ends of the ******* were bored on the lathe to ensure proper joint clearance.

Small objects (less than a golf ball) are readily soldered with a propane torch, esp. if a heat-reflective backstop (light firebrick, say) is used.

 

[cannuck]

If using Flux (psst, you. NEED to use Flux when soldering) how do you plan to remove the Flux from the air lines? When soldering water lines, the water flushes out the Flux. Air is not going to remove the Flux residue from inside the pipes.

I have a feeling you might have done this before. Can't emphasize how important cleaning and fluxing is. I like 95-5 for this job but noting your comment on flux removal (it is VERY corrosive) do you think filling, standing and flushing the air lines with water would be adequate? Assuming such fluxes are acidic the fill and soak phase could be done with caustic soda.

 

[bwringer]

We seem to have forgotten that the OP is sticking together air compressor piping, not medical gas, a rocket engine, potable water piping, a Mars rover, a nuclear reactor, a commercial freezer, a hazardous chemical plant, an aircraft carrier, or a steam boiler.

This is all very educational, though.