Any welders / brazers out there?

[280plus]

I have some cracked old cast iron radiators. I was wondering if brazing them might work? They would be subject to 15 psi x 180* water. Any other suggestions for repairing them? Just thought I'd ask...

[Guest]

I thought it couldn't be done but I was (write this down) wrong.

http://www.lincolnelectric.com/knowledge/articles/content/castironpreheat.asp

Looks like you can't do it for your purposes, but I was surprised you could at all.  I know cast iron pans can be repaired.

[Gewehr98]

That's a good link to have, Barbara!

I have an ancient 1873 Remington Rolling Block project that needs some pitting welded up.  I was scrambling trying to figure out if an iron frame receiver like that could ever be welded up.  Now I know.  

[280plus]

Thanx Barbara, The method is too involved. I have seen cast ron brazed with a oxy acetylene torch, I was thinking this might work. Poor guy, vandals broke into his empty house and disabled the heat. Then all his CI radiators split from the water freezing inside. I actually figured out how to split the sections apart so we could pull out the bad ones but I'm finding several where each section has split. One of those radiaitors new is $600-$1000 new depending on the size.

[K Frame]

280, skip the metal melting repairs on radiators. They're seldom truly effective. I've seen many attempts, and most are failures.

You can try stitching, but that's a nighmare. It involves drilling the crack and threading in plugs.

The best way to fix them?

High strength JB Weld epoxy. It will work up to 600 deg. F and take a LOT of pressure. Just fill the cracks according to the directions, leave cure, and then pressure test.

Oh, and you don't have to buy new radiators.

Hit an architectural salvage yard, or even a scrap yard, and you can often get hot water radiators for $15 a section, or less.

Just make sure that you get hot water radiators, NOT steam radiators. Yes, there is a difference. A hot water radiator will work on a steam system, but not the other way around.

Also, if you decide to go separating sections, you may run into problems with leakage. There were a lot of radiator manufacturers around over the years, and many used very different methods of sealing the sections, from crush nipples to section washers to sealant compounds.

A high temperature silicon sealant can be your friend in ensuring leak free joins.

[Larry Ashcraft]

High strength JB Weld epoxy.

exactly!

There is one product that works slightly better, but is hard to find and expensive: Devcon Liquid Steel.  Runs about $50 per pint.  It has been used to fix broken gear teeth.

[caseydog]

Good article , but it completely ignores brazing. Cast iron can be brazed with good success and since brazing is a comparatively cool process, it stays well back from the critical heat point and stress cracking is less of a problem. Typically a small stop hole is drilled at each end of the crack and the crack is well cleaned (dremel can do it) then braze it up.

Welding is somewhat more problematic , typically it involves cooling over a wood fire over a period of 5-8 hours , or for less critical work a propane weed burner and a bunch of dry sand to bury the hot part in will work.

Ray

[280plus]

Thanx for the input folks, I have thought about the epoxy "welds" and we are working at finding some salvaged ones. Either way theres a lot of work involved. I did seperate somke sections and found only push nipples. I'm thinking some sealant in the holes before they go back together but wonder maybe they're actually harder to get back together than they were to get apart. I imagine there was a machine that pushed them together and I might not be able to reach the amount of pressure needed. But we'll see...



Casey, is there a specific rod or alloy I should use to braze??

[K Frame]

That's the problem, 280. You never know which rod will work best because the old manufacturers often used cast iron that wasn't the greatest. That's why my comment about the high rate of failures with the metal melting techniques. I've seen the same thing happen with the cast iron heads on old farm tractors. Hit and miss.

You can reassemble the sections any number of ways. One person I know (had a business in Pennsylvania repairing these old radiators) made an iron frame and used two bottle jacks to push the sections together.

You can also use threaded rods and large backer plates. Time consuming.

The several times I took radiators apart and needed to get them back togehter?

I took them apart with a sledge and wooden wedges.

I put them together with a sledge and wooden backer blocks.

[charby]

I have welded a lot of cast iron in the past, I had pretty good luck with a nickel rod and preheating the hell out of the part with a oxy torch. I kept it hot while welding and when done I buried it in preheated sand. Let it cool slowly, cast iron is really brittle and if it cools too fast it will rebreak.

Most of the repairs I did were in cast iron stoves, never anything under pressure or had to be subjected to a lot of stress.

I would search out junk yards for unbroken radiators.

Charby

[mfree]

Anecdotal about JB weld...

I seized a thermostat housing bolt in the head of my dodge shadow (2.2, if familiar). It broke below the surface. Then the first and second e-z outs broke off flush. Then I ruined a punch trying to tap it out (what the heck are they making those bolts out of anyways?). In the middle were lots of attempts with soaking chemicals, propane torches, etc.

Eventually I ended up dremelling that corner of the water box down to the threads and chipping the bolt out with a chisel.

I cleaned everything off good with brake cleaner, coated a new bolt in vaseline, laid it in the threads, propped it up and made some dams out of cardboard and poured a new corner in epoxy.

That held for 2 years, or roughly 30,000 miles or hard driving before it popped off. The second patch, just like the first, got me another 10,000 miles before i suspected it was leaking pinhole fashion, so finally drilled the hole deeper and tapped it.

JB Weld is OK in my book.

[280plus]

I took them apart with a sledge and wooden wedges.

The method I stumbled across, literally, cause I tripped over the wedge shaped block of wood and said, "Hmmmmm..."

I put them together with a sledge and wooden backer blocks

The method I was planning to use.

I'm thinking Indian Head Gasket Sealer for the nips.

The problem with all the crack fixes is I won't be able to trust them. One of them will pop open at like 3:00 A.M. on the coldest night of the year. Per Murphy's Law of course. It does look like we'll need to find some salvaged replacements. These friggers are huge, HEAVY and some are on the second floor!:O (I was hoping to get around all that )

I remember using JB Weld to fix a head on an old A/C compressor. It looked like someone had purposely taken a chisel and hammered a scar across the head face at a thin spot to cause a permanent, nearly impossible to find leak. I schmooed some J/B in there, let it set and sanded it down. Problem solved forever. Cracks in thin cast iron are a whole different ballgame though. I'm afraid something like J/B won't hold up to the repeated expansion and contraction of the heating system. I'm afraid braze won't either.

[caseydog]

I use Uniweld products , mainly because thats what my local guys carry :

http://uniweld.com/catalog/alloys/silver_brazing_alloys/silver_brazing_alloys.htm

Uni-1800fc at the bottom of the page , get and use the matching extra flux , the biggest problem with brazing cast iron compared to other metals is getting it to wet out, extra flux helps.

I can't help but think in this situation that the split outs are going to be pushed out quite a bit , getting them back to a tight crack is going to be very difficult. Also there is the strong possibility of unfound cracks , unless you have a way to pressure test them outside the house even being sure you have them back together tight is a problem. Just a crappy job to be faced with all around, best of luck to ya !

Ray

[280plus]

Yea, these things are split from top to bottom, not a lot of distortion though. The problem is there are so many sections that by the time I'm done it's going to be a lot of hours and THEN it might not even work. I am planning to test the ones I dismantled with air before reinstalling them.

Sad part is, I could just repipe and put baseboard in but the pipes in the basement etc are COVERED in asbestos. The guy says, "You can pull that off." I says, "No, YOU can pull that off. Let me know when you're done."

[K Frame]

You're dealing with what, probably 1.5" inlet pipes to the upstairs radiators? How many zones? Gravity or forced circulation?

Are you sure the pipes are covered with asbestos? One very common insulating method in years past was horsehair and plaster covered in burlap. That's what was on the steam pipes in my parent's house.

Look, if they're split from top to bottom on multiple sections, it's time for the guy to make an insurance claim.

And yes, JB Weld will PROBABLY hold up to the repeated heating/cooling on a radiator. The expansion/contraction factor isn't that great, but I agree, those splits are simply too large to risk.

Here's a thought.

Junk those radiators. Take them to a scrap yard and cash them in towards the purchase of good radiators.

[280plus]

Junk those radiators. Take them to a scrap yard and cash them in towards the purchase of good radiators.

Yup, that is probably the answer. Too bad they never developed light weight cast iron...

As far as the asbestos. My policy is that it's asbestos until a qualified lab tells me otherwise. I don't forsee this particular guy calling in any labs. A contractor like me can't claim negligence or "I didn't know" and people I know have found themselves in the hoosegow for extended periods of time. Complete with Bubba and soap without a rope.

[K Frame]

"Light weight cast iron"

Tell me about it. I grew up in a house heated with steam.

We renovated extensively and had to move radiators over the years.

Try moving a 4" high, TWENTY section radiator. Estimated weight was close to 750 pounds.

Brother did that thing throw the heat in the winter, though!

[280plus]

Sounds like hernia city to me Mine are big but I don't think they're THAT big. I'm thinking rigging company to do all the heaving and ho-ing.