Removal of Scale Formation at Brazed Copper Joint

[bskwared]

The installer used an argon gas purge when installing ACR, type L, cleaned for oxygen service piping. It is being reported that scale is forming at the interior of the brazed joints. This means the purge was not done properly. In lieu of removing the piping, is there a method for cleaning the scale from the interior of the piping and once cleaned, can it be expected to return?

 

[chicopee]

Am I to assume that the scale is from the flux used while brazing the joints? If so check w/ brazing supplier about chemical treatment.

 

[bskwared]

A fluxless brazing process was used.

 

[chicopee]

You got to find out what mechanism prompted the scale.
If it was the heat while brazing then I would say that once the scale is removed there s/b no recurrence.
Now removing the scale is a tough one. You did not state how many joints and feet of piping you have. Also how critical is the quality of oxygen. Is it used for welding? life support? Another word must the scale be removed at all cost?

 

[CerrJohn]

To directly answer, is there a method, yes, you can clean the entire system with an acid pickle, but it is probably cost prohibitive unless the system is large, and the bad joints extensive. The cause was almost certainly bad purge/procedure, and you need to fix that.
Other alternatives would be cutting out the bad joints and installing "pup" sections, or replacing the pipe altogether.
Scale is bad in an oxygen system because it can cause particle impingement hot spots and: a) worst case it could explode or burn,
as well as oxidation which will:
b)contaminate the gas, bad for industrial processes, and very bad for medical gas for obvious reasons,
c)fail the piping and fittings.
The danger is higher for purer O2 concentrations.