Patching a pinhole on cast iron pipe

[WaterTight]

Cast iron kitchen waste pipe. Small pinhole has appeared on reasonably straight piece of pipe in a very inaccessible corner of kitchen cupboard. Other than replacing piping is there a patching / clamping type fix that will work?

 

[stevetheplumber]

i go for milliput clean the area first with sand paper to get a key

 

[Guest123]

If it's a soil or vent pipe, a small cutting of flashband with some bitumen primer painted on first will seal it.

 

[johnnyplumb]

flashband or denso tape will seal it. as a matter of interest watertight , is there a boiler condensate pipe connected to the sink waste ?

 

[WaterTight]

Thanks everyone. As it was the first suggestion I went out and got some milliput (had never heard of it, googled it and thought it sounded fun to try.)

Have since googled flashband (yes I'm an idiot) and that looks good too. Would you apply the primer to the flashband or the pipe? Or doesn't it matter?

Oh and no, no condensate. Why?

 

[WaterTight]

(i'm guessing something corrosive to cast iron gets chucked out?)

 

[wheeto]

(i'm guessing something corrosive to cast iron gets chucked out?)

Yes. The condensate is acidic which speeds up corrosion of iron pipes. Which is why you don't dump un-neutralized condensate in cast iron stacks. Modern PVC is fine.

 

[SimonG]

Did a temp repair once on something similar with a piece of rubber and a jubilee clip. Cust didn't want 'proper' fix.

 

[johnnyplumb]

(i'm guessing something corrosive to cast iron gets chucked out?)

seen one a few weeks ago, the underside of the cast iron sink waste pipe was corroded along the whole length of the pipe,
a condensing boiler had been fitted 2 years previously.
as has been said, condensate is acidic and corrosive to iron, etc.

 

[Guest123]

WT, paint the bitumen paint onto the pipe first and this will give something really strong for the flashband to adhere to.

 

[Bernie2]

Hmm! I know its not waste pipe, but I patched some cast rainwater pipes with car body repair paste, it was still there I think about a month ago. The thing is I patched it in 1984. I would not use Flashband its for roof and glass work and it is dear, beside the primer sticks all over the place. I think milliput sounds good.

 

[WaterTight]

To update / possibly conclude the thread, Milliput seems to have worked. Or rather it's been 24 hrs and I've not heard back.