Does anyone know how this happens

[OffshoreGas]

Shaun Cobbs has a point as excess flux can slowly rot a pipe from inside.

Could be one of 1000 factors or more likely a combination of them. Manufacturing defect, damage during installation, a small piece of dissimilar meter detached from a valve or fitting upstream, turbulent flow/cavitation, excessive flow due to to higher pump speed, the presence of flux etc. Hard to know what the actual cause is with something like this.

 

[centralheatking]

The best tube and fittings are medical standard , we used them years ago when we did medi gas.in hospitals ...oxy and vac
then we did some hydrogen in certified labs and nitrogen to cool down laser things ..awesome quality
centralheatking

 

[Stigster]

Shaun Cobbs has a point as excess flux can slowly rot a pipe from inside.

Along with overtightening compression fittings, people using excess flux really gets on my nerves like very few other things do, almost irrationally so it seems! There's just no need for it. It runs down the outside of the pipe, often past where you end up cleaning after soldering, it runs down inside the pipe and can cause "occlusion corrosion" and great blobs of it can get baked on inside the fittings again causing occlusion. I follow the WRAS guidelines and never flux the fitting either as it isn't helping anything. Even for those that do clean the pipe they were working on properly after soldering, I've seen people have excess flux drip all down over any pipework clipped in below which they usually fail to notice and clean.

STOP IT! ;-)

I do a demo in the workshop where I show just how little flux can actually be used, purely to make a point, not as good practice. I clean the pipe with cleaning strip enthusiastically, apply La-Co flux, wipe the flux away with a clean cloth and can still make the joint properly. In practice a little more flux than that is required but it does show the pointlessness of using tons of the stuff.

/rant

 

[Excite]

Yes...looks like excess flux

 

[Mdljk]

Could it be uncleared flux?

This gets my vote as a likely reason. Excess flux used on nearby fitting can settle onto interior surface of pipe and over the course of time the acid in the flux can corrode the pipe from the inside creating a pinhole.

 

[WC1]

I've often thought any tiny flake of steel or other metal coming off the tooling in the factory would do a good job of pinholing the tube after a few years.