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Re: Silver solder or just lead free solder?

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  • geoff burrows
    Hi Andy and Darald, (my comments are in line in blue) I totally agree with you about pressurized vessels and wouldn t even think of anything other than welded
    Message 1 of 7 , Mar 29 1:06 AM
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      Hi Andy and Darald, (my comments are in line in blue)

           I totally agree with you about pressurized vessels and wouldn’t even think of anything other than welded vessels for pressurized containers


      > Great information from
      everybody! I plan on using copper pop rivets every 1 inch and then soldering the lap joints together.

      Andy

      > >
      > > Hi Andy,
      > >
      > > As long as you do a good job pop riveting, the sheet joins
      will be
      > > strong enough.
      > >
      >
      > You MAY have
      enough strength in the connections. Pop rivets are quite good
      > but their
      consistency level is not that good for anything that would be
      > considered
      a pressure vessel. Anything that contains a pressure greater than
      > 15 psi
      is by definition a pressure vessel and MUST be built to
      > specifications
      written for pressure vessels.  Our stills are NOT pressurized vessels so this information although good and very note worthy has no relevance to our hobby stills except to making good welded joints.  Now if you have something where
      >
      there are NO restrictions to atmosphere then you can build it any way you
      > want.  
      style="COLOR: #4f81bd; mso-themecolor: accent1">Exactly if you look at, and fully understand our hobby stills, it is blatantly obvious they are open with no restrictions to the atmosphere.As has been pointed out time and time again by more  experienced people than me  (You can build it any way you want even if it is for over 15 psi but
      > then if there are problems a massive shelf
      of books (ASME code is about 6
      > feet of binders of information) will hit
      you and it will hurt!)  I’ve seen a caged split rim lorry tyres (I think they are illegal now) explode and that is a spectacular sight and we only got it to 40psi so I understand what a large volume of air pressure can do This comment
      > was written this way because there
      was absolutely no guidance on what
      > constitutes a ´good´ joint. This
      topic is not one that can easily be
      > addressed in a brief note either.
      There are many books written on the
      > topic.
      >
      >
      > > All you are doing with the lead free solder is sealing any leaks where
      your
      > > ethanol/steam vapour might escape.
      > >
      >
      > If you are doing an open to atmosphere system why would you want the
      work of
      > doing both?
      style="COLOR: #4f81bd; mso-themecolor: accent1">  The shape and construction of some of our hobby stills, need a certain amount of integral strength hence the pop rivets (not everyone has access to a welder or can weld hence the work around).  The lead free solder is to stop our precious ethanol from escaping from our still before we get it condensed
      > > Yes the soft lead free solder will give it a bit
      more rigidity if used
      > > in conjunction with the pop riveting.
      style="COLOR: #4f81bd; mso-themecolor: accent1"> Pop rivets by their very nature are basically a swivel point waiting to happen if not used correctly and to a well thought out plan.  The lead free solder helps any would be racking of joined parts and sealing the system.  But solder on its own just butt
      > > joining copper is not
      really strong enough.  I would never advocate a soft solder butt joint hence the following statement.  On the other hand a bent over
      > > copper seam, pop riveted and soldered is as strong as you're
      going to get
      > > with copper sheet.
      style="mso-spacerun: yes">  I’ve planned, re-roofed (to very high building code specification I might add) and worked on a  copper domed roof in Cheetam Hill Hospital in  Manchester.  So I know how to cut join and work with copper sheet sizes and their expansion co-efficients etc.
      > >
      >
      > Well - - if you are doing a pop riveted joint you
      definitely DON´T have a
      > butt joint you have a lap joint even for your
      welding.  I know read previous comment
      >
      >
      > > Also don't forget if you are
      hammering or working your copper sheet a
      > > lot, it will work harden
      and will snap so to soften the copper again heat it
      > > bright red
      (that's called annealing) and let it cool it will soften
      > > nicely and
      be more malleable. To clean the copper again I used to use a
      > > mild
      pickling solution like at this link http://tinyurl.com/2gxer4y   I cleaned all my copper projects in the flat cut sheet format (it's easy this way) and cleaned everything in lots of warm soapy water then bent joined and assembled them.  Its  called common sense but you are probably correct not everyone has common sense you can’t buy it that's for sure and scaring pads are probably the way to go if you are unsure.  
      > >
      >
      > If
      you use any kind of solution to remove the annealing heat effected zone
      >
      then you need to very carefully clean the solution off of the material too
      > or you will be trapping corrosion and corrosives IN your lap joint -
      - a
      > really bad idea and that will cause failure.
      style="COLOR: #4f81bd; mso-themecolor: accent1">Not an issue  if you clean properly as in the previous comment.  

      Geoff

       

      It might be just easier to use

      > some kind of abrasive pad (scotch-brite has at least 5 or 6 levels
      of
      > hardness/abrasiveness available).
      >
      > I am a licensed
      and ticketed pressure welder and I am a tinkerer so I am
      > trying to
      insert some care from BOTH sides of the equation!!  > Darald

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