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  1. fpnut

    Brazing of threaded joints

    How common/safe is it to braze a threaded joint? Not looking to do it, just curious since I came across a really old piping manifold (30+ years old) that was still in use. Seemed to me like an threaded valve brazed onto a block. I'm just wondering how common it is, or any pros and cons of doing...
  2. fpnut

    Interference fit for plastic parts

    I ended up making a silicone gasket cut out of sheets. Works fine for now while a redesign is being worked on. Any recommended books on designing plastic parts?
  3. fpnut

    Interference fit for plastic parts

    I'll look into it, thanks.
  4. fpnut

    Interference fit for plastic parts

    Well the diffuser manufacturer (and most of them) offers it only from HDPE/UMWHDPE, so I don't have much of a choice here.
  5. fpnut

    Interference fit for plastic parts

    The difference is about 35-130 x 10^-6/K (diffuser is HDPE, the inner part is PC). In regards to creep - the parts will be interference fit, so probably yes.
  6. fpnut

    Interference fit for plastic parts

    I don't have experience designing plastic parts that mate together, so I'd appreciate some pointers. Basically I ordered plastic gas diffuser that will be pressed to fit, and I have made the inner diameter of the filter too loose, causing gas to leak from the mating surfaces. Both diameters I...
  7. fpnut

    Looking for gas pipe flow experiments with published results

    1503-44, I initially thought about it, but decided against it for privacy reasons. Littleinch, He did do a table for different pressures, but only for a few pressures, since that's all we are dealing with at the moment. I plan to gather data using existing field installations, perhaps that...
  8. fpnut

    Looking for gas pipe flow experiments with published results

    Thanks all for the discussion. Well my application is relatively simple and not complex/critical like those in O&G requirements. And it's more of scratching a personal itch rather than doing it for production work. I recently started work in a company mainly doing gas distribution...
  9. fpnut

    Looking for gas pipe flow experiments with published results

    Hi Goutam, thanks, I'll have a look at Crane. Hi Katmar, thanks, I'll do some verification based on your links.
  10. fpnut

    Looking for gas pipe flow experiments with published results

    Hi All, I've just made a simple spreadsheet for estimating pipe diameters. Since my application is for gas, lower pressures (<30 bar), short lengths of pipe (<30 metres), relatively low pressure drop, I've opted for a simple Darcy-weisbach equation, coupled with Swamee-Jain friction factor...
  11. fpnut

    Increase fluid temperature after a throttling valve

    Hi All, I recently came across this problem, though I am not responsible for it, but found it interesting nonetheless. A chemical plant recently replaced a valve for a cryogenic liquid (ethylene). Previously they had been using a ball valve, but for some reason they chose to use a globe valve...
  12. fpnut

    Electric Actuator in Oxygen Service

    I've scoured over the internet looking for information on this, and there seems to be little to no information on the track record of such usage. I did find one company with a picture of what looks like an electric actuator on a copper piping line that is implied to be oxygen. The company didn't...
  13. fpnut

    Electric Actuator in Oxygen Service

    Hi MR, Thanks for the detailed explanation. Looking at those documents and the risks involved, I think I'll have to change the design to avoid using electric actuators. I am aware of those documents, but have not consulted them. In regards to the oil/grease, assuming pneumatic actuation is...
  14. fpnut

    Electric Actuator in Oxygen Service

    Hi, I am in the process of designing some pipelines for gaseous oxygen, and is in need of an actuated shut off ball valve. Typically I would use a pneumatic actuator for this service. However, for this application there are no compressed air or nitrogen available for actuating the ball valve...
  15. fpnut

    Strength of brazed copper tube

    It's the yield strength, which will be the reference limit for stress calculations.
  16. fpnut

    Strength of brazed copper tube

    Are there any ways to estimate tube/pipe material strength after brazing operation? The application I am looking may require a section of thick walled H80 copper tubing, and the joins to a brass block by brazing. I am aware that brazing basically anneals the material, causing it to have lower...
  17. fpnut

    Brass/Bronze valves on SS316L pipes on seashore

    It will be rained on, and will be under the sun. But the hottest it will ever get is being under the sun at max 38-40 degrees C. Lines won't be insulated. Since it's a part of a vapourising system, introducing as much heat as possible is desirable.
  18. fpnut

    Brass/Bronze valves on SS316L pipes on seashore

    Hi Edstainless, Thanks for your input. As for the 316 corrosion, we don't have much choice in materials as this section will be cryogenic. We are looking into other alternatives, but currently we are exploring the use of an aluminium based coating to protect the surface. Have you had similar...
  19. fpnut

    Brass/Bronze valves on SS316L pipes on seashore

    I have used brass/bronze valves on 316L piping before, and the results have generally been good. However, this time I'll be using it onshore, next to the sea. Anybody have experience with galvanic corrosion in this case? I'll be piping nitrogen. I'm worried about the atmospheric condition. Is...
  20. fpnut

    Budget 3D Cad recommendation

    Hi Everyone, I'm looking for a budget 3d CAD that is simple enough to learn but can do assemblies and BOM generation. I mainly design piping systems, some mechanical parts and assemblies, and also some structural stuff. As a background: I don't have any experience in 3d CAD, since I never found...

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