Cutting Barrel Steel Pipework For new cylinder

chloeradhsaw · Apr 23, 2023

I have a hot water cylinder which has low carbon steel pipework to it - I have tried to add some pictures

I need to replace the cylinder because it is leaking and I am not able to find anyone who is comfortable to work on this this because it is barrel steel - Has anyone worked on this kind of system before?

1) It i try and put some stillstons on it am I likely to get the nut to crack and the thread to remain intact? This looks like heavy duty commercial pipework so I am nervous but I need to get this reduced to copper so I can replace the cylinder - I have found a shop which has black iron fittings that can thread onto a 2inch pipe and reduce it but it depends on geting the but off in tact

2) If I have to cut the steel pipework without a thread can I use a Priomfit compression nut? Are these leak proof and reliable for water?

ShaunCorbs · Apr 23, 2023

Tbh do you have much experience in iron as it’s one of them, what type of property is it ?

chloeradhsaw · Apr 23, 2023

ShaunCorbs said:
Tbh do you have much experience in iron as it’s one of them, what type of property is it ?

Hi 0 Its a domestic house - Have only ever worked with copper and soldered copper - Never worked on iron pipework

ShaunCorbs · Apr 23, 2023

Easiest way then would be to undo the unions and adapt from copper from then remember if it measures 11/4 od it’s 1” tube so need 1” make irons etc

chloeradhsaw · Apr 23, 2023

How likely is it the steel pipe cracks below when i am exerting force to undo the nut ? I will heat it and use stillsons of bottom of the union but will this crack or twist up the pipework? If the pipe splits how do you fix it as I cant solder onto steep so thats why i looked at primofit optoins

ShaunCorbs · Apr 23, 2023

chloeradhsaw said:
How likely is it the steel pipe cracks below when i am exerting force to undo the nut ? I will heat it and use stillsons of bottom of the union but will this crack or twist up the pipework? If the pipe splits how do you fix it as I cant solder onto steep so thats why i looked at primofit optoins

You will have to hold against but will only snap if it’s weak so needs replacing

chloeradhsaw · Apr 23, 2023

Here is a better picture so you can get a sense of how frightened I am !!!

The cylinder has flow on top right, cold water in on bottom right and return on bottom left with hot water draw off on top of the cylinder

SimonG · Apr 23, 2023

Same as Shaun, take back to a joint and adapt to copper.

ShaunCorbs · Apr 23, 2023

Don’t do the job then say sorry out of my comfort zone etc

Chuck · Apr 24, 2023

I wouldn't use Primofit to make a direct copper-steel join in the pipework that is feeds CW to the tank or draws DHW from it because of galvanic corrosion. Use a purpose designed union or a brass transition section. It's fairly common to use brass-bodied valves for the transition, which are just about long enough.

TBH, this doesn't look like a DIY job if you don't have experience of, and the tools for, steel pipework. Try to find someone who does 'domestic and commercial' work rather than just 'domestic'.

SimonG · Apr 24, 2023

Failing what Chuck said above, an agricultural engineer may be the way to go. Lots of steel on farms.

Timmy D · Apr 28, 2023

I deal with this all the time. I wouldn’t use primofits unless zero other options.

Unwind from a joint and convert. It’s no particularly difficult but old steel does break and you need a back up plan, just in case.

Here’s one I found last week while replacing a bath for shower. Steel pipe rusting from the outside. Had to dig out back to a joint and replace.

Out of interest, what area of London are you?

chloeradhsaw · Apr 28, 2023

Yes the above is def steel barrell pipe - Want to say thank you to this forum - I managed to angle grind the cylinder out and then blow torch the connectors and they came out easily! Was amazed.

Have now bought a fittings to convert to copper and could not have done it without the immense knowledge on this forum.

I am in finchley - Now need to find someone to install a vented indirect cylinder - That certainly looks and sounds easier then messing with barrel pipework

WoodyP · Aug 21, 2025

Timmy D said:
I deal with this all the time. I wouldn’t use primofits unless zero other options.

Unwind from a joint and convert. It’s no particularly difficult but old steel does break and you need a back up plan, just in case.

Here’s one I found last week while replacing a bath for shower. Steel pipe rusting from the outside. Had to dig out back to a joint and replace.

View attachment 83094 View attachment 83095

Out of interest, what area of London are you?

Hello

I have just read your reply to someone who has a had a problem with barrel steel pipework.
We have an old house and a barrel steel pipe that services the boiler and heating has been discovered leaking and corroded. Several plumbers have been round and it's not something they can help with.
Would you be available to help?
We are near Saffron Walden Essex.
I'm getting concerned that i can't find anyone to repair the pipework

Very much look forward to hearing from you or anyone you may know that can advise.
D.P.

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Cutting Barrel Steel Pipework For new cylinder

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