How should I connect to a 4 inch cast iron water main

[Hargate]

Hi
I want to replace some old iron water main pipe and broken stopcock ideally with a larger bore pipe eg 28mm. In digging into the basement floor i found that the rougly 1 inch iron pipe comes off a 4 inch? Cast iron pipe. Not sure i dare try to unscrew the end cap.
Should i just cut the iron pipe and start from there (it would mean that a short length of pipe would be smaller bore than the would want) or is ther a way to tap into the side of the cast water main?
Possible useful info!
There is a stop tap on the road for isolating.
The above ground iron pipe runs for about 20meter with 3 no longer functioning stop taps on it.
Then it changes to copper drops to 15mm (!!) then to 22mm and splits into 4 x 22mm runs. This is why i would like the replacement section to be 28mm
Any suggestions welcome.

 

[ShaunCorbs]

How big is your external stop tap, I very doubt you have a 4" supply

 

[Hargate]

How big is your external stop tap, I very doubt you have a 4" supply

The external stop tap is big! Have a look at the pic i posted. The smaller pipe coming out of the big cast pipe is 1" so give or take the main is 4inch. It is stamped Staverly 1938 on the end cap but no size that i can see.

 

[snowhead]

Is this 4" just feeding your house and the 4 x 22mm runs are internal to it?

 

[ShaunCorbs]

The external stop tap is big! Have a look at the pic i posted. The smaller pipe coming out of the big cast pipe is 1" so give or take the main is 4inch. It is stamped Staverly 1938 on the end cap but no size that i can see.

Any chance a pic of the external stop tap as it's not there only the internal pic and will be 3/4 if it's inch dia

 

[Hargate]

Any chance a pic of the external stop tap as it's not there only the internal pic and will be 3/4 if it's inch dia

I can try for a picture in the morning. Its about a meter down and full of debris. Might take a while !

 

[Hargate]

Is this 4" just feeding your house and the 4 x 22mm runs are internal to it?

Yes. But it is a big house. Used as a party house. 17 bathrooms 13 kitchens

 

[ShaunCorbs]

Yes. But it is a big house. Used as a party house. 17 bathrooms 13 kitchens

Right that explains a lot

Will be a 4" main

Cut the pipes and undo it out of the cap 3/4 -28mm male iron in and off you go

 

[Hargate]

Right that explains a lot

Will be a 4" main

Cut the pipes and undo it out of the cap 3/4 -28mm male iron in and off you go

Thanks. You make it sound so easy! Do you think it will just unscrew using a big wrench or is there trick to it? Guessing it has not been touched since 1938.

 

[ShaunCorbs]

Thanks. You make it sound so easy! Do you think it will just unscrew using a big wrench or is there trick to it? Guessing it has not been touched since 1938.

18" stils if it doesn't undo add some heat via a blow torch

 

[Hargate]

18" stils if it doesn't undo add some heat via a blow torch

Brilliant. I will give it a go. Thanks for your help.

 

[king of pipes]

Plan ahead if you are going to attempt this dig it out a alot more there is going to be alot of water in that pipe you will be contaminating that main when the trench fills up a sludge pump will be needed to remove access dirty water , i would connect 32mm mdpe in its place .cheers kop

 

[Hargate]

Plan ahead if you are going to attempt this dig it out a alot more there is going to be alot of water in that pipe you will be contaminating that main when the trench fills up a sludge pump will be needed to remove access dirty water , i would connect 32mm mdpe in its place .cheers kop

Hi Thanks for the advice. I will definitely clear it out a lot more as much as anything to have better work access. it looks like it is in a brick lined chamber so pumping water out should't be too much of a problem. the main come in at an angle as well so not too much should come out.
Are you suggesting the mdpe as it is underground?

 

[king of pipes]

Download a copy of the water regulations for England and wales you have to get this right . cheers kop

 

[rasmo]

Wouldnt be keen on disturbing that 4"

 

[jonnyswamp]

Wind up?

 

[justlead1]

Hi. It looks like a spun cast pipe with a tapped stop end. It is difficult to see whether the stop end is a push on. The reason i mention this is that unless supported (you will be removing old gav pipe and earth) there is a possiblity that when mains work is done and turned on the stop end will have less support and move with dyer consequences.
To tap 4" main take around 30 mins with right equipment local water board have them on there vans or contractors do. Tapping it on the top say 450 mm from stop end with a new brass ferrule
would be a sound option for a new supply.

 

[king of pipes]

but the iron pipework will need sorting and there is a chance of blockages due to build up of sediments in a cast main if it is just blanked off take good sound advice get a professional in. Cheers kop