leaky join in underground waste pipe

[ASHP newbie]

Does anyone out there know exactly why every builders' merchant tells me not to use washing up liquid to lubricate 110mm pipe joins but every builder who's ever done any drainage work for me has always used washing up liquid (usually my own!). I assume it damages the seal - softens? or rots? it.

Is that why when I disturbed a join in my pipe it started leaking (slightly)?  Only one join leaks. The others are quite solid/tight, the leaky one is wobbly.

Or is it more likely to be because the pipe has been cut too short to fit far enough in, making it wobbly/leaky?  

If the latter I'll need to add pipe and another join blah blah blah. Incidentally both ends are fixed so will need to fight with a slip coupler. Always terrified that I won't be able to put it all back together.

I've been slowly digging up the waste system of my cottage because some idiot had put it in with an uphill slope at one point. Having sorted that I thought I ought to check the next section of the run. Not even a glimpse of sand or pea gravel anywhere, but lots of lumps of concrete, bricks etc.

[nod]

Silicon grease is better 
If I have to squeeze a straight joint in 

I knock the lugs off the fitting and slide it over one of the pipes Then slide it back when the pipes are together 

 

[Mr Punter]

Sometime the rubber seals can get dislodged during fitting. If you have a multi tool you can neatly and easily cut into the pipe and use a band seal coupler to repair.

[Cpd]

2 hours ago, ASHP newbie said:

Not even a glimpse of sand or pea gravel anywhere, but lots of lumps of concrete, bricks etc.

in my experience it’s very forgiving stuff, I am afraid I have never used  pea gravel or sand on my own property.... I always make sure the trench bace is very Clean and at the exact fall by checking with a laser, lay the pipe and hold down with big stones, fill in around it with whatever I have available or what’s come out of the trench. When the pipe is secure I remove the big stones and complete the fill in process, the only place I would pay special attention to is where pipes cross a driveway or yard / anywhere I might be driving over it with a landrover and a 3-4 ton trailer. I also use washing up liquid ....... 

[Gone West]

The pipe ends should be chamfered so they don't push the seal out of it's housing and a small amount of silicone grease applied to the seal. The pipe should be fully inserted into the fitting. Using washing up liquid will damage the seals but is a lot cheaper than silicone grease hence why builders use it.

[ASHP newbie]

Thank for all the info/advice. Problem solved as found that there were no seals at all in the join. Now got straight fitting in place and no leaks. Did use washing up liquid (and chamfer on the pipes etc etc).  Sand/pea gravel is better than lumps of concrete that I dug up lots of and which caused a sag in the pipe resulting in another short horizontal section (now removed). I tend to do what I have seen builders do in the past on the assumption! that they know what they are doing. Whoever put in these waste pipes did NOT know what they were doing. Nice to be able to start filling in the trench. Still don't know just HOW washing liquid causes damage.... Shouldn't be so curious.....

[Gone West]

3 hours ago, ASHP newbie said:

Still don't know just HOW washing liquid causes damage.... Shouldn't be so curious.....

Apparently it causes the rubber to harden over time.

[Crunchynut]

I would imagine that rubber hardens with time anyway! 

 

All of this theory makes me laugh. Expansion, slip, movement etc etc. All nice on paper but what of the real world?

 

In my experience, any pipe / join that has been in the ground a few years is rock solid and the only way to get it to move is with great force (eg I have used a hydraulic jack to separate a fitting from a pipe before now).

 

 

 

[kommando]

What makes washing up liquid thick is added salt, it's the salt absorbed into the rubber that's the issue and why it never should be used when mounting new tyres.