Solder Joint Failure - why would it fail?

[SkipFeeney]

Hi,

Came home tonight to a leak in my downstairs toilet. Turns out it was dripping at this solder joint here.

Leaking joint

• SkipFeeney
• 10 Feb 2018

This house was built 20 years ago, and the solder joint has been fine for 20 years - I just find it odd that it would fail after 20 years?! Just interested to know how this could happen? Its not been leaking before - just started today.

Thans

 

[pete50]

Solder will deteriorate and water solder and copper together form an electrolytic combination. It's probably been forming the pinhole that the water leaks through for years but only now has managed to make it to the outside world. All joints are leaks waiting to happen. Some will go quickly others will go after a long time even others will go beyond yours or mine lifetimes but sooner or later they will leak. Tis the nature of things.

 

[Hairymelon]

I am often reminded what an idiot I am but I thought galvanic action occurs when ferrous and non ferrous metals are in contact. Copper and lead and tin are non ferrous I think

 

[Doggit]

And I'd have to second that - the latter not the former that is. A good soldered joint will last for years and years, and a bad one (as Pete so rightly pointed out) is a leak waiting to happen. Now it may have leaked at the start, and then got sealed with calcium, and sometimes, the leaks so small that the water evaporate, but no one knows what the true cause is, so it may be just one of those things.

 

[terryplumb]

That joint was very badly done originally ,hardly Any solder around the copper pipe end ,and a big blob on the outside ! Amazing it lasted so long ,was it under mains pressure ,or from a gravity fed system ?

 

[Dan Robinson]

That joint was very badly done originally ,hardly Any solder around the copper pipe end ,and a big blob on the outside ! Amazing it lasted so long ,was it under mains pressure ,or from a gravity fed system ?

Have pulled systems or over the years where the pipes were held in by friction alone. Next to no solder in the joint, just a little ring around the end of the fitting with a the under side. Yet it held for 30+ years.

 

[endecotp]

I thought galvanic action occurs when ferrous and non ferrous metals are in contact.

It depends on the relative electrode potentials of the metals. See e.g. the list of metals at https://en.m.wikipedia.org/wiki/Galvanic_series ; if you have two metals in contact, the one that is furthest down that list will corrode. Steel is below copper, so when you have a steel-copper joint there is a danger of the steel corroding. But tin & lead (traditional solder ingredients) are above copper, so when solder and copper are in contact, the COPPER will corrode and the solder won't. Since there is a lot of copper around and only a small amount of solder, you won't notice the small amount of copper that oxidises and the solder will not corrode at all.

 

[pete50]

I am often reminded what an idiot I am but I thought galvanic action occurs when ferrous and non ferrous metals are in contact. Copper and lead and tin are non ferrous I think

So by that thinking a battery isn't going to work. Damn no wonder my car never starts.

 

[Hairymelon]

a lead acid battery is a different thing that is charged and retains electrical power. Maybe

 

[FiremanT]

We have all seen these, mainly when ripping out. I live all the technical guff, when the answer is simply that the joint was not made properly.

 

[dilalio]

I’m still amazed at the amount of “no-blow’s” I come across that have held together for years!

 

[HERTS P&D]

I’m still amazed at the amount of “no-blow’s” I come across that have held together for years!

Many of the women that I went out with were 'no-blows'. They never lasted long.



Andy

 

[Nige F]

My wife is like my joints................ discreet, attractive, but mostly never seen. Shame on you Andy

 

[oilboffin]

The simple answer to the question is it looks like a ****e joint.Bob