Too long in descaler?

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Too long in descaler?

Home Forums Beginners questions Too long in descaler?

Viewing 13 posts - 1 through 13 (of 13 total)
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  • #210285
    Brian G
    Participant
      @briang

      A friend put some boiler fittings in diluted Kilrock (formic acid) overnight to remove limescale and remembered them a week later. Unsurprisingly the parts are now bright pink, but we wondered if any damage may have taken place deeper into the metal that could affect their performance?

      Thanks for any advice

      Brian

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      #7848
      Brian G
      Participant
        @briang

        Formic acid pickle used for descaling

        #210299
        RJW
        Participant
          @rjw

          Sounds like a similar reaction to brass left in Horolene and similar brass cleaners containing ammonia where the ammonia strips the zinc out of the surface of the metal, if the fittings have been left in the acid for that period, personally I'd bin them and replace.
          I've no experience with boiler fittings at all, so other more knowledgeable people may advise differently, but there are cases where a similar reaction with ammonia based cleaners have caused microscopic cracks in the metal and subsequent fatigue failure.

          John.

          #210366
          frank brown
          Participant
            @frankbrown22225

            The acid has dissolved the zinc. I have had marine fitting which went like this and had zero tensile strength. "Honest Guv, it just came off in my hand".

            Frank

            #210494
            Brian G
            Participant
              @briang

              Dezincification was what worried me, although in this case I wasn't sure which metal would dissolve first. Fortunately it looks like a lucky escape as my son just heard back from our friend that the parts involved were all bronze and appear OK.

              Thanks

              Brian

              #210534
              Michael Gilligan
              Participant
                @michaelgilligan61133
                Posted by Brian G on 03/11/2015 19:11:42:

                … just heard back from our friend that the parts involved were all bronze and appear OK.

                .

                You probably know this, and I admit that it is a gross simplification, but;

                note that Bronze is an alloy of Copper and Tin [whereas Brass is a mix of Copper and Zinc]

                MichaelG.

                #210540
                julian atkins
                Participant
                  @julianatkins58923

                  Michael,

                  that is a bit of a 'cop out'! i was hoping for a full chemical analysis and treatise!

                  my old friend Jack Poyner who wrote the MAP book on electro plating gave me a bottle of concentrated formic acid for descaling boilers. Jack was a chemical wizard. unfortunately i found the formic acid not that effective on baked on limescale in miniature loco boilers. i never tried it on anything else and still have half a bottle in my shed.

                  cheers,

                  julian

                  Edited By julian atkins on 03/11/2015 22:03:47

                  #210547
                  Michael Gilligan
                  Participant
                    @michaelgilligan61133
                    Posted by julian atkins on 03/11/2015 22:03:16:

                    Michael,

                    that is a bit of a 'cop out'! i was hoping for a full chemical analysis and treatise!

                    .

                    smiley

                    Sorry, Julian … You're not going to lure me into even attempting that !!

                    There are so many variations on the Bronze theme that I wouldn't know where to start.

                    Apart from the Tin vs Zinc constituent, I believe that the most important difference is that [as I hinted] Brass is a mixture rather than a true alloy, and therefore the Zinc is 'accessible' to chemical attack.

                    Beyond that, I'm lost.

                    MichaelG.

                    #210552
                    julian atkins
                    Participant
                      @julianatkins58923

                      Michael,

                      i am disappointed!

                      there was a thread on here awhile back re a commercial brass blowdown valve that had badly corroded. my view of same was that the fitting had been overheated when silver soldered as a fabrication. ive had same last 30 years in miniature loco boilers.

                      citric acid (diluted) will produce the same 'pink' characteristics as Brian described after 3 hours. dezincification is quite discernable as a crystaline effect. this is quite distinctive.

                      cheers,

                      julian

                      #210573
                      Michael Gilligan
                      Participant
                        @michaelgilligan61133
                        Posted by julian atkins on 03/11/2015 23:00:56:

                        dezincification is quite discernable as a crystaline effect. this is quite distinctive.

                        .

                        … because, in Brass [especially in cast Brass] the Zinc is in 'macro' size and its removal [by evaporation, or by chemical attack] leaves visible crevices and holes.

                        MichaelG.

                        #210576
                        jason udall
                        Participant
                          @jasonudall57142

                          Wasn’t aware of the macro/nano difference .

                          Brass can be supplied in very “tight” recipe. .and similarly in very loose recipe.

                          As can many other materials used…
                          For example bronze. .

                          These “alloy”..to some extent are just mixtures.

                          Tin/lead solder for instance is called a eutectic mix ( ironically more an alloy than mix )..where does this leavw us?

                          Well there is a reason why certain fittings/parts are specified in bronze rather than brass…
                          If nothing else tin is much less reactive than zinc ..and would not fizz away and leave the amorphous copper stranded.
                          Btw alibronze..anyone?

                          #210578
                          OuBallie
                          Participant
                            @ouballie

                            MichaelG,

                            Now that you've made a start on that treatise, please continue devil

                            Geoff – Waiting in anticipation smiley

                            #210579
                            Michael Gilligan
                            Participant
                              @michaelgilligan61133
                              Posted by OuBallie on 04/11/2015 08:44:30:

                              Geoff – Waiting in anticipation smiley

                              .

                              Will this get me off the hook for a while, Geoff ?

                              MichaelG.

                              .

                              Edit: This page might be more relevant to the present discussion.

                              P.S. … Here is another useful reference.

                              Edited By Michael Gilligan on 04/11/2015 08:58:45

                              Edited By Michael Gilligan on 04/11/2015 09:09:55

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