Spray foam

Impala

Ok, I'm still in the drunk brainstorming stage. So everyone relax.

I'm thinking I can fix a cracked boiler section with spray foam. The crack is on the top far above the waterline. It's the last section. What I'm trying to do is kill/cut off the top of that section.

I figure I'll drill 2 holes fill it with foam which will float on the water, the foam will fill up the top space and the boiler will run on 4 sections instead of 5.

I'd love if people told me why that wont work in a scientific way so I learn something. Instead of the standard, fix it right, call a pro, spread your cheeks, kinda stuff.

ethicalpaul

I see some possible problems.

First, your thinking about it floating on the water seems faulty. You said it was far above the water line. Do you mean you’ll shoot it in there and it will fill the entire void above the waterline? That doesn’t seem great. How would you know when to stop filling?

Another problem is loose chunks of foam will float around and get stuck between sections possibly affecting steam and water flow. You’ll never be able to get them out.

Another problem is with heat. I’m not sure about this one but here goes. At the bottom of each section the temperature is limited to around 212F and foam is fine there (at least inside it would be), but at the top I would think the lack of water could allow the metal to be much hotter.

I think JB Weld is the better way to go, but even then just to scrape by until replacement, not a fix.

Look at the bright side. You get a chance to get a boiler that is for sure the right size.

Gordy

Spray foam won’t adhere to that rotted wet casting very well, if at all.

IF it were even successful it would change the dynamics for making steam. You decreased the volume of the hx

ChrisJ

What temperatures does the top of the block above the water line see?

Spray foam is good to 240f I believe?

nibs

Spray foam is not monocellular, it will become waterlogged, I don't know if waterlogged foam will float, but I think not.

Gordy

> @ChrisJ said:
> What temperatures does the top of the block above the water line see?
>
> Spray foam is good to 240f I believe?


Hilti makes a spray foam sub 200 degrees 176 to be exact.

mikeg2015

ChrisJ said:

What temperatures does the top of the block above the water line see?



Spray foam is good to 240f I believe?

Above the waterline, the metal is likely well above 215F, it’s probably close to 300F as this is the “superheating” section and steam is a poor conductor of heat compared to water, so the metal could be 300F even on the inside.

JB weld is good to 500F. Might be able to make a “patch” of some sort out of thin carbon steel hammered into shape, then seal it with JB Weld.

How big is the rusted out area?

Might be better downfiring the boiler somehow (need a pro to do this) to get pressure down to ounces at all times, to limp it along.

SeanBeans

For reasons unknown to myself, I would recommend to not go through with that idea

HomerJSmith

I would use whipped cream, like Redi-whip and if it doesn't work one could eat it.
Polyurethane produces cyanide gas when burned, but don't let that stop you.
There are products out there that seal cracks in boilers and fireplaces. I don't know how well they perform, tho.

Jolly Bodger

Spray foam is not a sealant. It not closed cell and till not stop water, especially under pressure.

There are not many options that will hold any pressure. A skilled welder could braze on a patch.

Gordy

Not a lot of pressure in a steam boiler. IF set up properly. Ounces of pressure.

HomerJSmith

Jolly Bodger, you don't realize how hard it is to weld cast iron. It is like welding cast iron blocks on automobiles. Cast iron has to be heated up to a certain temperature before welding can even be done.
Deep down in the recesses of my failing memory I recall reading about a welding product that could work without the heating.

ChrisJ

> @HomerJSmith said:
> Jolly Bodger, you don't realize how hard it is to weld cast iron. It is like welding cast iron blocks on automobiles. Cast iron has to be heated up to a certain temperature before welding can even be done.
> Deep down in the recesses of my failing memory I recall reading about a welding product that could work without the heating.

I believe you also have to keep it from cooling fast.

HomerJSmith

Yup! All this is why it's not done.

Jolly Bodger

@HomerJSmith @ChrisJ I do understand how hard it is. My first profession is welding. You are right about the difficulties in welding cast. I have done it with reasonable success. I suggested brazing, which is not welding. Still requires good skill but is commonly used to repair/join cast iron.

I have tried many glues, cements, and epoxies over the years. I've found that they don't seal to cast iron reliably.

@Impala , if you put a glue product on it. Clean, clean, clean, then clean it again.

I've torn out more than one boiler that someone killed a section with cement. They still leaked.

Gordy

Cast iron can be welded. Just different procedures.

Gordy

Honestly I’d try a permatex sealant beFore anything else.

ChrisJ

> @Gordy said:
> Cast iron can be welded. Just different procedures.

Ok,
And since it's a very difficult procedure that means the op needs to hire a welder to come do it. Do you think it'll be worth it?

Gordy

depends.

Where is the crack/hole.

How did the crack occur? Stress, rotted out etc.



I’d try homeowner alternatives first. Not spray foam. Job weld, permatex etc.

Gordy

https://www.lincolnelectric.com/en-us/support/welding-how-to/Pages/welding-cast-iron-detail.aspx?utm_referrer=direct/not+provided

HomerJSmith

A crack is different. A hole can be drilled, tapped, and plugged.

ChrisJ

No one would pay a professional welder to come and weld a rotted residential boiler. It's completely unrealistic.


So ultimately welding isn't an option.

That's all I'm saying.

Gordy

For the cost of a new boiler. I agree.

EBEBRATT-Ed

Welding high quality cast iron is possible. Boiler cast iron isn't the best quality and welding something that is dirty, rusty and usually in a location difficult to grind and wire brush makes it impossible.

Since the crack is above the water line clean it as best you can and use JB weld epoxy on the crack. Then down fire the burner as much as possible, keep the pressure low. Find a good installer and make plans for a new properly sized boiler

Jolly Bodger

Sorry guys! didn't mean to hijack the whole thread.