Cracked Cast Iron Radiators

[MasterPlumbersKeymaster]

I have 2 cast iron radiators that cracked when too much steam built up in heating system. Need to know if and how to repair or if there is a salvage yard in central Illinois or St Louis, MO area. So far the nearest supplier is in New York.I now have some options. Thanks Masterplumbers
[Edited by Sara on 18 April 2000]

[SylvanLMPParticipant]

Hi Sara something is very, VERY wrong if your radiators cracked from “too much steam” as

1- These devices can hold much more than the 15 PSI steam pressure
and once one cracked the pressure should have dropped right away.

2-Your boiler should be equipped with a 15# Safety (POP) valve that should have discharged the excessive pressure. (15+ is excessive)

What could have caused these to radiators to crack is water hammer ESPECIALLY with the velocity steam is capable of achieving.

Now repairing a Cast Iron radiator is not that difficult if your lucky where the rupture occurred.

If you look at your steam radiator you will see rods holding these sections together if you loosen these rods you can remove the damaged section and reuse the steel push nipples.This will shorten the radiator BUT it will work.

Another option is getting a great Sulfur product called “Black and White” you apply this to the cast iron crack with the use of a blow torch just heating the base metal AFTER really cleaning the heck out of it. It will hold for many years BUT you must use it out doors if you have a large crack to fill.

When I repair a cracked boiler in the winter when I don’t have the time to replace it I just drill a hole on either side of the crack to prevent this crack from expanding and I weld this cast iron BUT the key to welding CI is the cooling down period must be slow as not to thermo shock the weld/base metal

If you contact “Mikes Pipe Yard” on Boston Road in the Bronx section of NY they can sell you 2nd hand radiators about $10.per section. The shipping may not be worth it as you have no idea if these 2nd hand ones will leak or not.

Personally I would opt to removing the defective sections if possible OTHER wise just replace these radiators with new ones.

If you plan on using your existing radiators give them a hydrostatic pressure test of 11/2 times your normal working pressure.

You can also braze these cracks with a Bronze filler rod which is not that hard to do BUT get a good Quality rod like Union Carbide 25M. The main thing right now is to find out what exactly caused these 2 radiators to crack before you do anything else. Most steam heating systems operate well under 10 PSI most can work with even a 1/2 psi

I work on buildings with the original steam radiators installed in the late 1800s and they are still in pristine condition.

Good luck and please keep me posted.

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SylvanLMP

[Author]

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