Clay v Plastic drain pipes.

[Mottie]

Thames water are replacing our 60 year old pitch fibre drain pipes due to them collapsing. They are using clay pipes. Reading up, it seems plastic pipes are better - cheaper, come in longer lengths so less joints, smoother, roots don’t get a hold on them, flexible, last longer etc. When I asked them why they were using clay and not plastic, all they could say was 'we never use plastic - clay is better, stronger and lasts longer'. That the opposite of what I am reading on the 'net. Surely if plastic was better and cheaper, they’d use it, wouldn't they?

Any idea why they are sticking with clay?

 

[mrrusty]

https://www.thameswater.co.uk/media-library/home/help/home-improvements/building-near-our-pipes/specifications-for-sewers-up-to-160mm-diameter.pdf

Last point.

 

[Hugh Jaleak]

Modern Vitrified Clay drainage is as good as the plastic stuff, (possibly better is some respects as will withstand higher loading, and High pressure Water Jetting), but you've hit the nail on the head in your original post, it's cheaper to buy and install, hence why it's more widely used.

A decent saw and file is all that's needed for cutting and jointing plastic, all offcuts can be used, etc. Clayware need a disc or chain cutter, cut ends can be sharp and are harder and more time consuming to chamfer.

Water Companies also employ a lot of Civil Engineers that are not concerned with costs, so specifications are often higher. Often when a connection is done from a new development, the Water Co. may insist on Clay being used from the point of connection to the first manhole within the boundary of the development.

 

[^woody^]

I wonder if the clay pipes are being fitted with plastic collars, or mortar and rope like in 1850?

Check out the green links down the left - www.cpda.co.uk/pipe-characteristics/why-specify-clay/ - but as Mandy noted, "they would say that wouldn't they".

 

[Mottie]

I wonder if the clay pipes are being fitted with plastic collars, or mortar and rope like in 1850?

The pipes are in about 5/6ft sections and yes, they are using some kind of black plastic collar to join them together.

 

[Koolpc]

They probably have tons of the stuff lying around in storage....

 

[noseall]

I detest clay stuff. We work with it, but switch to plastic as quickly as possible.

 

[noseall]

Modern Vitrified Clay drainage is as good as the plastic stuff, (possibly better is some respects as will withstand higher loading

What I find with clay is that once buried and under pressure from the soil above, it's a pig to cut through
in-situ. The downward soil pressure usually means that the last bit of clay pipe wants to split off, ridding you of a clean cut.

 

[noseall]

or mortar and rope like in 1850?

Ahh, that tar smell in the morning....

You haven't lived unless you have had your grubby hands around some tarred rope, trying to thread it around the female end of an old salt glazed pipe.

 

[Hugh Jaleak]

What I find with clay is that once buried and under pressure from the soil above, it's a pig to cut through
in-situ. The downward soil pressure usually means that the last bit of clay pipe wants to split off, ridding you of a clean cut.

Agree, its a PITA to work on in a trench, usually in the most awkward spot, with numerous services in the way.

 

[tell80]

We've never had the least difficulty in cutting pipework in trenches - using a Stihl 14"cut-off, or a Recip Saw with
various brands of excellent blade choices eg. Milwaukee or Tiger - or if needed the chain, snap-cutter.
Recip blades will cut HD cast iron and salt glaze.

 

[noseall]

We've never had the least difficulty in cutting pipework in trenches

Me neither. It's a faff, but you need to make room for the machine. Recip saws are ok but tend to wander and you still need to chamfer the ends.