Best metal for bushings for cast iron hot water radiators with steel pipes?
I’m confused and would appreciate advice from someone with experience.
I like stainless steel, but I’ve heard it can damage cast-iron threads during installation or removal. Still one of Toronto’s largest cast-iron radiator shops (Ironworks), sells only stainless-steel bushings.
Brass can lose zinc and become brittle. Is that a concern with a high-quality brass adapter, such as Parker, in an older heating system that’s mostly—but not completely—free of air?
Bronze seems ideal, but the specific bushings I need are impossible to find in the specific length.
Steel rusts and looks bad.
What’s the best choice?
Comments
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why not Steel?
Brass with lead I like
Stainless Steel damaging cast iron is a new one on me. Stainless is actually cheaper then brass
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No need to reinvent the wheel. I would concider steel the best choise
Miss Hall's School service mechanic, greenhouse teacher, dog walker and designated driver
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steel or brass. steel is fine service wise but can seize if you ever have to remove it and has to be cut out. brass is more likely to unscrew as long as you don't collapse it.
i know stainless can gall threading on itself but I didn't think it would do that threading in to cast iron.
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Most ""Black" bushings are Cast Iron. In most locations steel bushing are usually only available in the smaller sizes like 1" and under. Anything large r than that is usually CI.
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It's an existing installation in a basement, old reducing bushing was pretty rusted, I'd like the new one to never rust. Also the new bushing needs to 1-3/16 long, those mostly come-on brass or stainless.
Has anyone seen either of those last 20+ years problem free ?
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no issue with mixing brass, bronze, stainless, copper with an iron radiator. Most of the valves that connect are brass with a brass tailpiece.
Blue Monster has a special tape and they had a grey colored pipe dope for stainless.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
From what i understand brass valves ares low zinc, under 15% also called DZR.
Typical brass adapters are made from standard brass that has more zinc and is susceptible to losing that zinc over time and becoming brittle. That's the theory anyway.
Am i overthinking this or has anyone actually seem regular brass adapters becoming weaker over timer?
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What is the radiator made of? Has it rusted away? I believe a cast-iron radiator will be just fine with a cast-iron bushing. Black malleable-iron bushings are also fine.
If the bushing has rusted away then it was getting wet on the outside and that was the reason for the failure. many people paint the radiators so they don't rust. Try painting the bushing the same color as the radiator. That is why they make paint in matching colors.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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dezinification of brass was mainly due to aggressive chemicals in some potable water. DNZ brass has been used on potable water components for some time. It got a listing standard around 1980.
For hydronic stuff mostly the same DZR and low lead brass is used now.
It is a complicated procedure for a brass manufacturer to work different types of brass. Tooling, and lubricants need to be switched in all the machines. Shavings from machining needs to be segregated.
If you do find the older leaded brass products, you usually find a disclaimer with it. I see some of the leaded brass valves at SHT.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
I'm sure valves and such are mostly DNZ but apparently most bushings are not. They are lead free but not resistant to zinc leaching out.
Has anyone seen stainless bushings come out of cast iron radiators? Any issues with corrosion or seizing ?
Stainless isn't galvanically compatible with cast iron, not sure if it's an issue on this case given the small size of stainless and general lack of oxygen.
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i've seen lots of stainless seize while threading loosely on itself…
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Do you plan on removing the bushing often?
Why the concern about seizing?
The dezincification was on potable piping where water constantly changes.
That is why you still see heating, or non potable brass that is not DNZ.
Put a can of Fernox in the system if corrosion is your concern.
Don’t over think this, get you heat going, its getting cold outside
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
stainless will gall quite badly with itself which is why for SS to SS its good to use the special tapes meant for it. It generally behaves better with other metals and galling is less of a concern there.
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Stainless threads, or any threads do not seize while being loose unless there's a severe problem like damaged threads or metal chips / dust in the threads.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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Yes. Not trying to be negative but yes you are overthinking. Just use CI or steel fittings and you will be fine
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Actually the stainless nut and bolts on solar collector mounts do often sieze of gall when you try to remove them. The damage is probably during the tightening process.
I think all stainless threads are prone to galling. More so if you overtighten them and distort the threads. I would put chap stick on the threads of stainless nuts and bolts on solar mounts. Maybe make it easy on the next guy or gal?
Here is what I use on stainless pipe threads. Probably work on nuts and bolts, but it is extremely hard to wash off your hands
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream
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i use permatex anti seize and wear disposable gloves
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steel will stretch before failing. If you’ve ever tried removing a locked bolt you will get movement before it breaks. Stainless is brittle and doesn’t give much warning. Overtighten it and the threads begin cracking.
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There's a lot of things id call 300 series stainless and brittle isn't one of them.
That's why it's so much fun to machine, it's very malleable much like aluminum but it's also very hard at the same time. It's hard to break chips when drilling because of how malleable it is. It's also why tapping it and trying to go back and forth is a bad idea, you usually bind up rather than breaking chips.
@hot_rod I said no stainless steel thread will seize when loose unless something is really wrong. If it was already tightened, that's not loose
Though, I had no idea blue monster made anti seize.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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the ones i have had seize usually were after i loosened them while i was backing off the extra thread of the bolt
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