Jump to content

92½° Bends and 90° corners


TerryE

Recommended Posts

We've got a couple of Gerberits where the soil pipe comes parallel to the wall, does a 90° bend and runs a metre or so along to the stack.  To minimise boxing in, I would like the pipe to run parallel to the wall, but the Gerberit frame fitting fixes the socket square to the frame and if I loose the extra 2½° along the other wall, this pulls the pipe bend out about 5cm.  Grrrrgghh!!  Does anyone know who does a true slow 90° bend in 110 PVCu?

Alternatively what is the trick to get around this issue?

Link to comment
Share on other sites

Can you use a small straight offset fitting to get around the problem?  I had to fit one because my soil pipe stack coming out of the slab was very tight to the frame inside, and IIRC this gave me around 30mm or so of offset in a straight pipe connector, enough to be able to fit the soil pipe vertically with clips to fasten it to the wall.  There also adjustable bends, like this:  https://www.drainagesuperstore.co.uk/product/110mm-0-to-30-degree-adjustable-single-socket-bend.html that might help, I'm not  quite sure what it is you need to do.

There is another option that I have used in the past, although I'm not sure it's recommended practice, and that is to put some force on a length of 110mm pipe and then heat the outward facing side of the bit you need to to curve with a hot air gun, over a wide area.  I've managed to induce a very gentle permanent bend in 110mm pipe like this, with no kinks.  The key is to only heat the side that is going to stretch over the gentle bend, not the inside that's under compression, as that will make it kink.  The BT Duct 56 that curves around under the bottom of our drive has a 2m long swept bend made like this - it worked well and retained a nice smooth bore.

Link to comment
Share on other sites

1 hour ago, ProDave said:

When you find the solution, let me know, I have EXACTLY the same issue trying to take a 68mm rainwater pipe around a corner.

On our our wastes, I've been using a 135° into a 135° spigot bend and this produces a slow 90°, but this is just too slow for 110mm pipe.

1 hour ago, JSHarris said:

Can you use a small straight offset fitting to get around the problem? ... there also adjustable bends, like this:  https://www.drainagesuperstore.co.uk/product/110mm-0-to-30-degree-adjustable-single-socket-bend.html that might help, I'm not  quite sure what it is you need to do.

The smallest fix offset is 12½° and this is a spigot fitting so I need a female to go into it.  Might  work in some places. but the geometry doesn't work in my cases :(   I've looked at these bends including the 0-90° version but I just don't like the risk of these for near horizontal runs.

1 hour ago, JSHarris said:

There is another option that I have used in the past ...  is to put some force on a length of 110mm pipe and then heat the outward facing side of the bit you need to to curve with a hot air gun, over a wide area.  I've managed to induce a very gentle permanent bend in 110mm pipe like this, with no kinks.

Funnily enough your mentioning this.  I did the same trick 25 years ago when I plumbed the farmhouse, but I forgot about this issue on this house until I hit it again.  It's an option to try.

I just wish at least one supplier did true 90° bends.  I do get some hits but I suspect that this is just a loose description for 92½° ones.  

 

Link to comment
Share on other sites

The adjustable bends Jeremy mentions usually have quite a large collar on each universal joint so can be quite wide, depending on manufacturer. Fwiw, I've done plenty of soil stacks and have always simply pulled the pipe square. 

Never had a leak or a comeback tbh. 

You could use a clip at the outer edges of the run, and then use patent band / similar to fix at the elbow I suppose. That would put the bend tight against the wall in the corner and remove 50% of the overshoot. 

Ive never had a problem using 92's for exact 90o bends, and, if it's 110mm pipe runs, I'm really struggling to see the issue if I'm completely honest. 

@ProDave Your issue will be worse as there's little to no 'give' in rainwater products :(  I sell on all my exterior work tbh, so can't offer any help here, sorry. 

  • Like 1
Link to comment
Share on other sites

didn't want to be the first to say it but as Nick said, just pull it square, 

you could always cut your male end pissed if it helped you sleep at night but i really can't see it being an issue, 

FWIW i have heard mixed reviews about the adjustable bends, many say they have never had a problem, a few others have said they are always the joint that leaks, 

realistically as long as it is above ground and not encased in concrete whats the worst that can happen??

Link to comment
Share on other sites

7 minutes ago, Construction Channel said:

 

realistically as long as it is above ground and not encased in concrete whats the worst that can happen??

It can fail the pressure test while building control are watching....

Link to comment
Share on other sites

5 minutes ago, Construction Channel said:

didn't want to be the first to say it but as Nick said, just pull it square, 

 

Chicken :P

 

6 minutes ago, Construction Channel said:

 Realistically as long as it is above ground and not encased in concrete whats the worst that can happen??

Now you've gone and said it................

:D

Link to comment
Share on other sites

9 minutes ago, ProDave said:

It can fail the pressure test while building control are watching....

I haven't actually ever had the displeasure of having to do a leak test on the soils and wastes. Last few BCO's were generally impressed enough by the overall standard I displayed, and in most instances I'd gone above their remit, without provocation, so I think I got let off the hook. 

Last extension was a nice one, and I got the final sign off purely from emailing the BCO photographs of the required items / locations etc. He genuinely didn't come back to site after seeing the build through to to the insulation and roof etc, and only wanted the electricians certificate for conformation of locations of the smoke detectors. 

B I N G O 

Link to comment
Share on other sites

7 minutes ago, Nickfromwales said:

Chicken :P

I'm a "Jack of all" 

No point me suggesting a bodge until someone sensible has gone there first :P

But as for pressure testing you could always test that joint first, ......its not going to leak over that sort of jiggery pokery..... if it does,,,,,blame Nick :P

 

Link to comment
Share on other sites

19 minutes ago, Nickfromwales said:

I haven't actually ever had the displeasure of having to do a leak test on the soils and wastes. Last few BCO's were generally impressed enough by the overall standard I displayed, and in most instances I'd gone above their remit, without provocation, so I think I got let off the hook. 

 

They must be a bit more hot on that up here, or I look like a dodgy plumber.

In my present house they demanded an air test of each stack so I had to get the roof ladder up to plug the vent pipe out the roof, then grovel down in a chamber to get the test bung on then pump it all up.

"Why is is only pumping up to 3" not 4", there must be a leak."?

"Because the shower trap is only a 3" seal and any further pumping just blows bubbles through the trap (moron)"

Link to comment
Share on other sites

:D

I doubt if I'd have got on well up your neck of the woods, Dave. I'd have been locked up after being asked for 4 chuffing non return valves on the water supply :/ :S

The BCO's I've met have been really helpful, enthusiastic and 'sensible' tbh. The second they realise I 'know my onions' they backed off and the jobs went much better for it IMHO. I think if BCO's (i) treat you like an idiot, or (ii) get proven to be an idiot by you, then you soon develop a sense of disregard for them and on a self build you'd not suffer as it's your own job so you'll go belt and braces anyway, but if that happens to a builder on a private job, they're just going to try and cut corners to get one over the BCO. A stupid game of cat and mouse IMO. 

Link to comment
Share on other sites

29 minutes ago, Construction Channel said:

f8332056abfc6a8202dd0f2278611b6d.jpg

That sums up my current experience - old school, retired (70 this week) inspector, brought back part time to help out, took one look at our build and said he didn't like it, as it "hadn't got any foundations" and things have gone down hill from there.  PITA doesn't begin to describe it.  I'm going around fitting water flow restrictors and taking photos of them, as requested, as he has done a 180 deg turn on the agreement I had that I didn't need water saving measures because we have our own water supply and treatment plant.......................

Link to comment
Share on other sites

did you ask if he wanted you to put bricks in your toilet cisterns? :D

we had a similar NHBC inspector on the one and only job we used them, we called him 10 yr Ted and TBH it was almost getting to the stage of carrying out his instructions to the letter just to watch them fail and rub it in his face, eventually they had to send a different inspector because of the "abuse" 

ROFL some people just don't like getting repetitively proved wrong even if they do have a book,,, :D

Link to comment
Share on other sites

Nick something just doesn't square with what you are saying.  The M/F sleeve on a 110mm fitting is about 4 cm deep.  2½° over this distance is over 1½mm out of line.  The polypipe fittings just don't have that amount of play in them.  The forced 2½° is going to put a huge amount of strain on the joints, and will tend to cause failure at the weakest one.  At least Jeremy's 2½° banana trick is using the know plastic characteristics of PVCu in a way that will be memorised without building failure strains.   Need to think about this further. 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...