Repairing cast-iron downpipes

GRC

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The in-laws have what I would call a hairline crack in one of their cast-iron downpipes. The pipe as a whole seems to have been painted many times over the years, and it seems to me that the paint has peeled away and outward along the line of the crack to a width of 2mm or so, revealing the layer of base metal underneath, with a thinner crack evident in that.

Whilst the crack extends as a whole to some 40cm or so, it hasn't penetrated the whole depth of the metal along the full length. Pushing a feeler gauge into the gap, it meets resistance for most of the length, and only goes into the centre void of the pipe over a length of a couple of centimetres or so. The width of the crack in the metal at this point is maybe a millimetre or less.

I was thinking of using some kind of epoxy putty on the metal (Quiksteel metal repair from Amazon, maybe?), and filling the wider gap where the paint has peeled with Sugru mouldable rubber, then painting over it.

Any words of wisdom, or other suggested repair product?
 
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Yes. Replace them. You can get replica cast iron pipes now (some sort of fibre based plastic), they look very similar and won't hurt so much if they drop off the front of the house. You'll get a few quid from the scrapman for the cast, if any of them actually turn out to be perfect flog them online, it'll pay for their new ones
 
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drill an 1/8” hole either end of the crack to stop it spreading then clean the crack ,force some ct1 or equivalent into it and dust with fine sand or whatever to match the texture of the cast and paint.
 
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Usually a crack in cast iron is a crack in cast.. full depth.

i'd say renew it... you will only fixing it again next cold winter
 

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Will we ever get a cold winter again ... ?
 
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Those replicas look interesting, thanks for that; never even knew they existed
 
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They used to sell 2 types of replicas, Plastic and Metal ready painted and finished, Aluminum I think, did the work over 20 years ago, still good when we moved out 3 years ago.
I also managed to get the small bolts which joined the gutter parts together.
I did choose on their recommendation to use CT1 , which was excellent.
In fact still choose that , although I have been introduced to hippo pro3 , a lot cheaper and just as good, As mentioned only just started using it , so not tested fully yet
https://www.hippoproducts.co.uk/hippo-pro3.html
I replaced a whole section of gutter at the back of a old 1904 house using the metal versions. Joined and fitted the old gutter and downpipes fine, not sure if still available - but i purchased in Sutton Surrey angel plastics https://www.angelplastics.co.uk/
https://www.angelplastics.co.uk/Category/213/68mm-Cast-Iron-Effect-Round-Pipe
 
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If a repair is a must, your epoxy putty is the one.....I’ve even repaired tractor cast iron water jackets with it.
John :)
 

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FYI, I used a small tin of car bodywork repair epoxy to fill the base crack, slathered some CT1 over the top of that, and gave it two coats of paint. Seems to do the job so far.
 
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