Soil pipe SINGLE Socket Coupling

[DaveyH]

Hi,

I totally get what a soil pipe DOUBLE socket coupling does (it lets you join 2 pieces of soil pipe together).

But what does a single socket coupling do?

Here is an example what I'm on about. What's it for?

http://www.screwfix.com/p/black-single-pipe-coupler-sp124/62966

Here is an example of a double (I totally understand this one)

http://www.screwfix.com/p/black-double-pipe-coupler-sp105/47977

Thanks in advance

 

[sime10]

looks Like A solvent weld to pushfit coupling

 

[PrenticeBoyofDerry]

http://www.floplast.co.uk/uploads/downloads/Soil Waste ring seal soil system.pdf

 

[Charnwood]

As sime10 said, it is a coupler with one end ring seal and the other end solvent weld.

Single socket is a bit misleading. Perhaps a competition to come up with a more apt name?