Pickling

[Alan]

Hi Chaps
I believe you have to clean off the residue after brazing ( I am making a small copper boiler) I have seen a reference to "Pickling" am I on the right track ? if so I can't find out what solution one would have to make up to ensure all the fluxes ect have been removed.
Thanks

[lancelot]

Hi Cruise,...do a quick search on the ''Search programme'' using about 1000days and 50 hits...plenty of info there.
All the best for now,
John.

[circlip]

If you go to General Chat, Search tab on bottom of page, type in Pickling, 25 answers.

[brozier]

Hi CruiserMoi,

I use Sulphuric Acid diluted with water.

Easiest source of concentrated sulphuric acid is max Strength Drain Cleaner.

e.g. I have DrainKleen One Shot purchased from B&Q....

Add the 1litre of Acid to at least 10 litres of water.

Add slowly as it gets very hot. Wear the appropriate safety kit.

I keep mine in a bucket with a close fitting lid.

That strength will remove flux and oxidation within 30mins...

Cheers
Bryan

[Alan]

Thanks guys

Much appreciated,

Alan

[GWRdriver]

Alan,
A further bit of advice from my experience (quite a few boilers) . . . I quench my boilers as soon as I can get them from the hearth to the tub of water. I gently but quickly immerse them, which doesn't harm the boiler, and the thermal shock of queching blasts off 85% of the accumulated flux residue and black oxide (inside and out), and the pickle makes an easy job of the rest. I do NOT however plunge-quench a red-hot boiler. It need only remain hot enough to generate vigorous steaming on all surfaces.

When quenching a hot boiler mind the direction of the flues and other external openings. During immersion the flues can very often trap slugs of very hot water & steam which can come shoooting out. Simply keep yourself (and others) out of the direct line of fire of the flues and you'll be fine.

[Alan]

This is excellent stuff, it would take me years if ever to find out these gems of info.

Alan

[Deleted]

Be careful about the fumes coming off the pickle bath if quenching hot. One winter I did quite a bit of silver soldering in my (very) large garage. I had some old car instruments stored on a shelf and their mazak-type cast bodies didn't take kindly to the effect of the fumes. I now make sure that I can lower boilers etc into the pickle with my bare hands. I think that quenching from hot can induce unnecessary stresses in a newly brazed assembly. Probably a bit over-cautious, but I prefer to play safe. I have had some cracking around tube to tubeplate joints due to differential cooling. Its surprising that how few degrees above ambient the job (particularly copper) needs to be to give the pickle a bit of a boost in removing the scale.

[GWRdriver]

Please note that I did not say anything about quenching in the PEEKLE! But to clarify, Never quench in the pickle . . . ever . . . only in water. No good can come of airborne hot acid, except perhaps as the theme of a really bad space alien movie. We all have our ways of doing things, and Alan you will find yours, but I would not suggest a hot quench if any one of the number of boilers I've built appeared to have suffered from it.

I have found that when solder joint problems have appeared in my work, and they do from time to time, 99% of those can be attributed to failure of a joint to fully wick solder which in turn is usually attributable to inadequate joint preparation on my part. For that reason I expend a great deal of time fitting, relieving, channeling, chamferring, scrubbing, cleaning, and otherwise making it easy for the solder to run where it needs to go. I use plenty of flux and plenty of heat and things usually go pretty well.

[Deleted]

I would endorse all of Harry's suggestions. I was always taught that 'flux is cheap, silver solder isn't'

Geoff

[GWRdriver]

My sentiments exactly!