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16795Re: [multimachine] A big project!

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  • Dr. Alexis O'Neill
    Jan 29, 2013

      Forgive the delay, I've had a lot of fires to put out over the weekend and just got back to this. I have attached a basic report on anti-corrosion applications of thermal spray and hope it answers your question about the suitability of sprayed zinc coatings on petroleum pipelines as well as other installations in the field.

      Good luck in your research.


      Enviado desde mi oficina móvil BlackBerry® de Telcel

      From: Rodrigo <rcaetano22@...>
      Sender: multimachine@yahoogroups.com
      Date: Fri, 25 Jan 2013 17:31:19 -0200
      To: multimachine@yahoogroups.com<multimachine@yahoogroups.com>
      ReplyTo: multimachine@yahoogroups.com
      Cc: multimachine@yahoogroups.com<multimachine@yahoogroups.com>
      Subject: Re: [multimachine] A big project!


      Does anyone know if this process of thermal spray coating could be used as a external protection in pipelines?


      We have been using a polyethylene coating and cathodic protection to provide corrosion resistance, but i don´t know if the thermal spray is cheaper or better. I´m working with an iron ore pipeline here in Brasil and we have a great amount of pipes of 24" to protect.



      Em 22/01/2013, às 10:21, "Dr. Alexis O'Neill" <alexiso_nl@...> escreveu:


      The thermal spray process allows the melted wire to cool almost instantly, we spray with a standoff distance of around 6-9 inches, and by the time the particles hit the substrate, they have almost cooled. I can't comfortably touch a workpiece instantly after spraying, but within a minute or two I can. The adhesion is a mechanical process, there is no heat distortion with thermal spray. This is why we want to introduce the thermal spray here, we can reclaim worn areas over and over again with over-heating them like we do when weld-repairing. Our only problem is too much cold-working before or after spraying that can harden some types of steel and make it hard to grind a nice polished surface, such as equipment/installations in food or medical areas. We need a milling machine, too, but that's down the road, right now we can't properly prepare those huge shafts for spraying, so the lathe is critical, a milling machine would be nice, once we can get everything sprayed correctly. What we would mill would be big and heavy, too, ss plates weighing over 1-2 tons each. Back to the lathe, however.

      We do have plenty of big trucks here, we have a nicely developing trucking industry and the trucks here are the same as I've seen on US and Canadian highways. There are more and more new ones, which means old junked ones, and their trailers, so I think we could find parts without a problem. This idea seems interesting, I'm printing it out for Anibal's and Juan's perusals. Anibal works with pantographs and robotics, he will understand this idea and I'll pass on what he thinks.

      We don't care about pretty, just what works and is safe to use.


      Enviado desde mi oficina móvil BlackBerry® de Telcel

      From: "David G. LeVine" <dlevine@...>
      Date: Tue, 22 Jan 2013 02:00:56 -0500
      Subject: Re: [multimachine] A big project!


      On 01/20/2013 01:50 PM, Shannon DeWolfe wrote:
      Would this work? I know it isn't a concrete lathe but what is needed is 
      a solution to a problem, not an exercise in how big a lathe can be built.

      I don't think so because the surface will be so hot that I think the rollers would degrade.  That was why the head and tail stock.  With that kind of load a trailer can flex many inches.  Sorry, that doesn't seem to be a good choice.

      Now, support that roller only by the ends and unload the carriage and you could grind things pretty well, but that takes a LOT of power and the measurement tools are not cheap.

      Now for the "sneaky" side.

      Take a semi trailer and line it up with the head and tailstock (no load on the trailer means it stays relatively flat.)  It can carry the head and tail stock, but they set on the ground or concrete slabs.  Even a 500 pound carriage won't really flex the trailer much, and the grinder can be pretty light (relatively), but it will have to remove quite a bit of metal, let's say no more than 20 HP.  Rotation can be fairly low powered, under 100 BHP.  Now for sneaky:  Cheap laser diodes can be had (eBay or laser pointers) for a few dollars.  Mount two in the headstock (or more), use them to shim the tailstock and the ways into alignment.  Now, vertical doesn't matter much, remember I was trying for a few thousandths.  So the carriage can move and either grind or spray, two carriages can do both.  Air bearings make good sense, as do really stiff ways which won't bond to slag.  Let's say polished granite.

      Let's see what resources are available!  If a tractor (as in a tractor-trailer) with a PTO and a compressor, a semi-trailer and a little hydraulic power is reasonable, maybe we can ask some right questions...  The headstock and tailstock sit on the ground or pads (pretty low tech and cheap!)  The trailer goes between them and the ways get shimmed to the lasers.  Power comes from the truck, as does air and hydraulic drives.  With compressed air, we can clean the ways as we work.

      It isn't pretty, but it could work.  If we can get some fancy stuff done, the laser diodes can be used to find high spots...

      I have to look into laser interferometry.

      Dave  8{)


      "Among the many misdeeds of British rule in India, history will look upon the Act of depriving a whole nation of arms as the blackest."

      Mohandus Ghandi, An Autobiography, Page 446.

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