Kitchen sink pipes keep coming apart

[OckErt]

Hi all

Our kitchen sink / dishwasher outlet pipes keep coming apart, every few months. Sometimes it's when we empty the washing up bowl down the sink, sometimes there's no obvious reason.

Here's what it looks like:



The top arrowed join definitely comes apart, and maybe the lower one too. (When it happens we're more concerned with the flood coming out of the cupboard than a careful examination of the pipes.)

I'm not sure if the top join is properly fitted. Here it is taken apart:



The ring seems to be the right size and it's not perished (and only a couple of years old) but maybe the weight underneath is just too much for the friction to hold? Would a support under the u-bend help?
I turn the nut by hand only, should I tighten it with a tool?

All advice welcome.
Thanks
Dan

 

[rocketmanbkk]

Shouldn't come apart

Is there a thin blue washer in the nut part?

Very strange indeed

 

[bella100]

Looks ok make sure it's nipped up fairly well, and looks like a bit of tension from the dishwasher outlet

 

[OckErt]

Shouldn't come apart

Is there a thin blue washer in the nut part?

Very strange indeed

No, only the black o-ring

 

[OckErt]

Looks ok make sure it's nipped up fairly well, and looks like a bit of tension from the dishwasher outlet

"nipped up"?

 

[Plumbstar Tom]

"nipped up"?

tightened up fairly well is the translation

there normally is a blue hard plastic washer that sits above the black washer

 

[OckErt]

tightened up fairly well is the translation

there normally is a blue hard plastic washer that sits above the black washer

Thanks for the translation and for everyone's advice. I'll tighten everything and get a blue washer.

 

[JCplumb]

The cheaper compression waste fittings don't always have the slip washer in them, usually made of softer plastic too and you can't always tighten them up enough without the thread skipping.
My guess is cheap waste fittings (B+poo own brand stuff?).
Replace with McAlpine waste and trap and it'll be grand.
Oh and hand tight only, don't put any tools on there.

 

[OckErt]

The cheaper compression waste fittings don't always have the slip washer in them, usually made of softer plastic too and you can't always tighten them up enough without the thread skipping.
My guess is cheap waste fittings (B+poo own brand stuff?).
Replace with McAlpine waste and trap and it'll be grand.
Oh and hand tight only, don't put any tools on there.

Thanks, it probably is cheap stuff but I've added the slip washer and it feels a lot tighter.

 

[PETE 123]

If it was my house i would put a bit of wood under the trap to hold it up so it will never fall down.