Excess Flux inside Gas Pipe

[WhatNext]

Good Morning

I have a quick question for you all !

The other day I wiped off a very green stain from the copper gas pipe inside my house. The pipe runs to the boiler.

It wiped off with a drop Brasso and there was no sign of a mark on the copper, where the green stain had been.

I now understand that this is caused by flux which was not wiped off the outside of the pipe which over time has started to corrode the copper.

The copper pipework was installed in 2013 in a new house.

I understand that modern flux is non acidic.

What I am wondering about is whether any excess flux, that may be inside the copper pipework, could over a long time corrode through the pipe ?

I would appreciate your comments.

Cheers

 

[oldbuffer]

1. If done correctly:
1a. Flux is applied to the pipe only. When it is inserted into the fitting, any excess is scraped off onto the outside of the pipe.
1b. The excess should be wiped off before soldering, as doing so gives a neater soldered joint.
1c. The joint, once cold, should be thoroughly wiped with a damp rag to remove any traces of flux.
2. Many modern fluxes ARE acidic, which is what gives them their self cleaning properties.
3. As corrosion occurs it weakens the acid in the flux, so after some time the remnants become inert.
4. The chance of a pipe corroding through after 9 years are pretty remote.
5. If you want absolute certainty, you would have to renew all the gas pipework.

 

[WhatNext]

Hi Many Thanks

Out of curiosity is there a specific type of flux recommended for copper pipes ( to carry gas ) which can not / or are generally not flushed before being put into service ?

 

[oldbuffer]

1. It is rarely possible to flush pipes which form part of a gas carcase. Flushing is done with water, possibly with the addition of chemicals, and it is not usually possible to guarantee that all liquid has been removed.
2. There are non-acidic fluxes available, but I'm afraid I've never used them and can't remember the names.

 

[ianmcd]

as @oldbuffer correctly says flux should only ever be added to the pipe spigot and never inside any fitting, this prevents flux from being pushed into the waterway/gasway/sadly too many so called professionalls still put flux inside fittings, that is so not correct