Solvent weld alignment difficulties!

[smallsteve1]

I need to attach to existing pipe in the floor and then come up behind bathroom units, which only afford 50mm of clearance. The attached picture is my first attempt, which is not permanent as the connection in the floor has been done using compression.

I spent ages lining everything up and marking the pipe, but still managed to get it leaning out at the top, such that it is touching the unit; my permanent effort might even be worse, requiring me to move the units away from the wall! This is where I could do with some advice on whether there is a better way of doing it. :-/

Part of the problem is that trying to dry fit it is difficult as I can only get 10 mm of the pipe into the fitting. This means that the pipe can be slightly skewed and so even marked-up, it can move around a bit when glued and inserted; each joint then exacerbating the error. I did think about sacrificing some pipe by cutting a slot along it to allow it to fully insert into the joint when dry fitting, then using a new piece of pipe for each final fit. But I can’t believe anybody else is going to these lengths and so I must be doing something wrong!?



TIA

 

[just pumps]

I would start with a dry fit from the bottom upwards even removing and refitting the trap if it came to it. Then mark each joint with lines as to the final postioing, then remove and solvent weld it all and fit as one length.

 

[smallsteve1]

I would start with a dry fit from the bottom upwards even removing and refitting the trap if it came to it. Then mark each joint with lines as to the final postioing, then remove and solvent weld it all and fit as one length.

Thanks for your input. Just to be clear, are you suggesting that I solvent weld everything aside from the final underfloor connection and then dry-fit it to check everything is aligned? Then assuming all is well, weld the structure (essentially one-piece) to the existing underfloor pipe?

 

[CBW]

How do you know they’ve only gone in 10mm? Presuming it’s the elbow bit touching the unit, then the piece going to the trap needs to be longer then.

 

[smallsteve1]

How do you know they’ve only gone in 10mm? Presuming it’s the elbow bit touching the unit, then the piece going to the trap needs to be longer then.

That’s about as far as you can get the pipe in the fitting when not using glue i.e. with a dry-fit. I put a pencil line next to the joint after the fit, disassembled it and measured.
With the elbow nearer to the wall, where it needs to be, then I would need the pipe going to the trap to be a bit longer, yes. My uncertainty though is about the technique required to guarantee that I won’t repeat what has already happened and end up with the pipework slightly out of alignment as I don’t have the space to accommodate it. The o/d of the pipe is 36mm and obviously the connector widens it a little bit more. 50 mm (max) is all I have to play with.

 

[just pumps]

32mm solvent weld pipe fits into a fitting more than 10mm. measure inside a fitting up to the stop shoulder.

 

[smallsteve1]

32mm solvent weld pipe fits into a fitting more than 10mm. measure inside a fitting up to the stop shoulder.

I think we are at cross purposes here. A dry fit on Floplast is super-tight and the pipe only gets about 10mm before it sticks. When solvent welded it goes in all the way as it should.
When dry-fitting, I am finding that the partial insertion can lead to errors. I guess other brands may be a looser fit but have only ever used Floplast.

 

[CBW]

Why not try lubricating the joint with some water, see if it’ll go in more, then ensure the joint is dry before final assembly?

 

[just pumps]

I think we are at cross purposes here. A dry fit on Floplast is super-tight and the pipe only gets about 10mm before it sticks. When solvent welded it goes in all the way as it should.
When dry-fitting, I am finding that the partial insertion can lead to errors. I guess other brands may be a looser fit but have only ever used Floplast.

Give it a good push in as the actress said to the bishop.

 

[smallsteve1]

Give it a good push in as the actress said to the bishop.

Coincidently before your latest post, I’d tried exactly that with a straight connector and it slotted fully-in. With the bends though, it got 2/3 of the way before it stuck! I then struggled to get the damn things apart.
I then resorted to a dab of spittal and a bit of force and it popped straight-in no problem, thereby providing the solution to my problem.
Thanks for your help, it’s saved me a load of hassle.

 

[smallsteve1]

Why not try lubricating the joint with some water, see if it’ll go in more, then ensure the joint is dry before final assembly?

Tried that but it didn’t work. Then tried rubbing alcohol and that did work. I couldn’t get them apart though and so had to resort to a very weak solution of soapy water, which did the trick,. Five or six joints, and it would be a hell of a workout!

 

[just pumps]

Are you sanding any burrs off the end of pipe

 

[smallsteve1]

Are you sanding any burrs off the end of pipe

Yes, pipe prepared fully.