Issues with unscrewing 3/4" imperial pipework!

[Tubbsup]

Hi,

I am hoping for some advice from you good fellows! I have tried to add a picture, hopefully it has come out below.

It will probably be helpful if I add that I do not have a blow torch!

I am wanting to replace my upstairs toilet. Ideally I would like to connect to the right of the stop cock which is above the floor boards in the toilet room. The present pipework is 3/4" imperial. This pipework then continues onto the cistern. Am I correct in thinking this is lead piping?

One concern I have is if I put too much pressure on the attempt to unscrew the piece of pipe to the right of the stop cock a split might occur in another joint along the pipework, i.e. to the left of the stop cock, causing a leak. Also, if I do manage to free the pipe the attempt may wreck the thread, meaning I cannot then screw in a 3/4" x 15mm reducer part. A quick aside, with the pipe I need to unscrew, is that anti-clockwise?

Now, if I wreck the thread or cannot unscrew the pipe, I can still feed cold to the new toilet by coming off a metric cold pipe next door in the bathroom. However, that still will leave the open imperial pipe, after a failed attempt.

I have turned off the stop cock by hand and with some extra effort with an adjustable spanner. But, I am still getting the occasional drip in the cistern every half hour.
A question I have is: can I keep tightening the stop cock with the spanner, or will this damage the valve, thus producing a greater amount of water coming through?
If I just decide to feed the toilet from the metric pipe next door in the bathroom, I still have to cut the 3/4" imperial pipe after or at the stop cock as I want to remove the old piping that continues onto the cistern. Once cut at or near the stop cock I can then box in the remaining pipework.

Back to the issue of the open 3/4" pipework, I'd be grateful if someone has any advice on how to fill the open 3/4" pipework, bearing in mind there is a once every half hour drip coming from the stop cock, meaning, in time the pipe it will become full with water from the slightly faulty stop cock.
Will Boss compound with hemp create a secure fill?

Another question I need advice on is: is there a 3/4" x 15mm compression joint out there that has a nut and olive on the imperial side. I can't find one! For then I can just cut the 3/4" pipe and put this 3/4" x 15mm compression joint on.

I have read using a 3/4" olive and loads of ptfe tape can work? What do people think of that?

Also, could someone let me know what is the internal diametre of a 3/4" pipe?

Any advice would be very much appreciated.

Thank you.

Paul

3/4" imperial pipework!

• Tubbsup
• 18 Jan 2012
• 1

 

[muggles]

Only you can tell what the pipework is made of, you're the person on site. My guess would be steel though, and it's probably ½" rather than ¾" (imperial pipe sizes measure the bore, not the outside diameter). To confirm whether it's steel or lead, put a magnet on it. The magnet will stick to steel, it won't stick to lead.

You won't damage the threads unscrewing the pipe from the stopcock, but you need to be careful not to cause a leak on the upstream side of the stopcock by allowing it to move, it must be gripped firmly before you attempt any unscrewing. Not having a blowtorch may be an issue, if it fights your attempts to get it out the usual method would be to heat up the pipe near the stopcock to break the seal. It will be anticlockwise to unscrew.

You can try tightening the stopcock more with your spanner to make it shut off, sounds like it really needs a new washer though. Just nip it up a fraction further and see if that improves things.

If you cut the pipe you're pretty committed, you won't get anything to go on it that looks nice, you need a thread to connect on to. If the stopcock is passing and you just try to bung it up, you'll eventually end up with enough pressure behind the bung to pop it out again.

Internal diameter (bore) of ¾" pipe is three quarters of an inch, or about 19mm.

 

[fishhead1]

wrap with a couple of rags then blast with an airduster upside down,freezes a treat

 

[Tubbsup]

Fishhead, thanks for replying. However, I don't see how freezing helps at present.

And Muggles, many thaks for your reassuring message.

Refering to it, the pipe in question is 3/4". In my shed I found an old female end cap which has 3/4" stamped on it. This cap is the same size as the hexagonal end of the stop valve. Also from the shed I have a 3/4" x 22mm compression male iron coupling, and the 3/4" side screws into the old female end cap. Guided by you, I have measured the ID of this coupling I have and it's 3/4". Sorry to go on!
With this in mind, and returning to the 3/4" pipe I need to remove: I am grateful for your reassurance that the thread should be intact if I can unscrew the pipe from the stop valve. With the removal attempt itself, I will first of all be cuttung the pipe a few inches to the right of the stop valve, and then attempting the unscrewing. This means no pipework will be affected 'upstream'.

I would appreciate your comments on the idea of using a 22mm compression coupling, but on the imperial side remove the 22mm olive and use a 3/4" olive. Then add loads of ptfe tape to provide the seal?

I appreciate there's a point of no return once the pipe is cut. You then comment about 'you won't get anything to go on it that looks nice' How it looks wouldn't be a concern as I will be boxing in the pipework; I am more interested in some kind of filler that may be strong enough to fill the pipe. This is in case I come to the scenario of not being able to remove the pipe and that the stop valve keeps dripping, even after numerous further attempts to tighten.
Another option would be to change the valve washer. Would you say this could be problematic, considering how old the valve is?

 

[doitall]

You don't screw lead

 

[stardanny]

The picture look like iron pipe. If you want to reconnect to cistern,

cut the pipe a few inch away from stopcock.

Hold tight the stopcock with a spanner and use a pipe gripper on pipe to unscrew it anti-clockwise and remove it, it might be tight, use a blowtorch.

Clean up inside stopcock.

Use a 3/4 inch BSP male thread x 22mm comp coupler and run a PFTE around the thread and screw into stopcock and tight up.

Use a solder ring 22mm x 15mm reducer.

Add a 15mm iso valve.

Or if not using anymore, use a 3/4inch male plug.

Dan

 

[doitall]

If it measures 3/4" then it's 1/2" BSP.

 

[compheat]

Scrape the paint off the pipe and test with a magnet,
you can buy a fitting that is either 1/2" or 3/4" iron called PRIMOFIT this is a compression type coupling on one side and a female or male connection on the other.

You need to check what the pipes made of first

 

[Boilerman2]

On CWS you will find the pipe is GALVANIZED STEEL and it is 1/2"
why not cut back to the stopcock fit a 1/2"M.I - 15mm Copper and re-run from the S/C in nice new Copper? PS fit a new washer in the S/C as well!

 

[Tubbsup]

Many thanks for all your replies!!

As well as doing some more research, I am still trying to conclude whether I have the confidence to do the job.

However, thanks again!!

 

[Tubbsup]

I can now add that I have been successful in removing the piece of pipe I was asking about. Now I can easily continue on with copper to the toilet.

Many thanks to all you who showed some interest in my questions!

 

[Agile]

So what was the pipe made of?

I do have to say that to me it looked like copped with a compression fitting!

But pictures without any scale reference are very difficult to interpret. Best to take them with a ruler tape beside the item of interest.

Tony