Weird corrosion on valve fitting

Normally green deposits are from corrosion of the copper, but the position and colour (pale green rather than the blue-green for copper) suggests that it is coming from nickel in the fittings. It is possible that there is condensation on occasions as the incoming cold water is well below room temp. My suggestion - I am a graduate chemist familiar with the colours of various metal corrosion prodicts.

Malcolm

Wow -

Thanks Malcolm! Yes, these are plated fittings. So I guess nothing to worry about... I did wonder why the top fitting (pressure valve) did not show any - perhaps it's a different plating?

Cheers,

Tim

Rightly or wrongly I look at that, and see nature's Boss White :-)

That's what I thought at first...

I had a joint around the corner that I rushed and weeped for a bit, before it sealed up.

However that one had an obvious dribble down the pipe where this doesn't...

I'd go with that. Could be that you've had a bit of chloride around. You might give the joint a tweak in case there is a tiny leak (drying up faster than it leaks). If it hasn't changed in a month or two I would really not worry.

Probably just from water condensing on the cold pipe / fitting.

Yup, that would be my guess.

But why would it be so localised, just on the thread? My money's on a very slow weep. I had one on a compression joint that was very difficult to get at to tighten fully. No drips or even moisture obvious, but over years a brown encrustation built up on the thread, much like the OP's picture (our water supply comes through an old black-iron pipe and is iron-rich).

It's weird that it didn't seal itself though (your case or mine).

As I mentioned I did have some plastering done and blobs did get on this. Maybe I wiped it off OK, except for the threads.

What I don't want to do is tighten it more and make it worse...

you can see it on both sets of threads, and on the top of the lower backnut.

I think this is just a reflection of the fact that is where water will collect and remain in contact for longer - i.e. in the the nooks and crannies rather than on the flat surfaces.

If one were really concerned, you could dismantle the joint, and give a quick wipe with some LS-X on the mating surfaces before re-tightening to the previous torque.

I like that explanation :)

Just been swearing my head off putting the final 25mm of celotex and a sheet of plasterboard under the roof where I will be clipping my new mains pipe run...

I've seen such a pattern a number of times, I wouldn't worry about it.

NT

Thank you :)

Ah yes, plasterboarding the last awkward shapes in a roof space... I remember it well (but not fondly!)

I cheated - just whacked a couple of bits up and did not even cut around timbers! I concluded I needed PB down at least to about 2' from the eaves as this is storage/crawl space and heads and boxes hitting celotex would knacker it. Luckily prettiness is not required!

But access is awkward so I could not even get a sheet of 1800x900 in - had to snap it in half lengthways...

NOT looking forward to the creative pipe bending that will be needed to come under the roof, turn down through the ceiling, then offset bends to get it onto the wall then down the kitchen! There will be MUCH swearing next weekend.

It's a run I would prefer to use full soft thick walled copper if it were available in 22mm and short amounts (need about 4m)