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  1. weed78

    Split repad efficiency

    Just to get back to the original topic, PVinspector is right on. It may not be a nice thing to say, but unfortunately it is true, and sometimes truth hurts. Alberta has long considered itself as the savior of humanity by ever tightening controls for pressure equipment coming into its region...
  2. weed78

    SA36 Attachments in Low Temp

    A carbon steel vessel is made to Sect. VIII Div. I with MDMT -50°F. The vessel has external attachments that are subjected to loads resulting in stresses on the shell or head. Can such load bearing attachments be made from SA36 or even SA106B (not normalized nor impact tested), or must they be...
  3. weed78

    High Vacuum Differential Pressure

    Thanks guys, your thoughts are very helpful. The tank manufacturer is no longer in business and the tank is almost 40 years old. Is it reasonable to think that it may have outlived its usefulness? We did a Helium Leak test but found no indications of problems with leaks into the vacuum space. We...
  4. weed78

    High Vacuum Differential Pressure

    Thank you all for your comments, they are very helpful. iainuts: What type of problem with the perlite would develop if there was evidence of perlite dust? We are seeing some dust in the hose from the tank to the pump. wfn217: What do you mean by "molecular flow" and why would that cause a...
  5. weed78

    High Vacuum Differential Pressure

    We are trying to bring back to life an old perlite insulated liquid O2 tank. We have been pumping down the vacuum in the insulation space but can not get down below about 400 microns. With the tank isolated from the pump we pull down to less than 10 microns so the pump appears to be capable of...
  6. weed78

    ASME Appendix 2 Fabricated Flanges

    Thanks Mike, In this case we have a 2 1/2" thick 304 SS flange and we would like to make it from 3 plate segments, no hub. The only issue, I believe, is radiography, and I just can't see this type of construction addressed anywhere. Do we need radiography of the three 2 1/2" thick welds?
  7. weed78

    ASME Appendix 2 Fabricated Flanges

    A flange is designed to ASME Code Sect. VIII Div. I, Appendix 2 and manufactured in 3 x 120° segments welded together. Do these butt welds require any NDT? Any references for this construction? Thank you
  8. weed78

    High Vacuum Gauge Reading Stability

    We have an old perlite insulated cryo tank in which we are trying to improve the level of vacuum insulation. We are down below 1 torr but are witnessing wild fluctuations in the reading of the vacuum gauge. It is a digital gauge made by Kurt Lesker. If we close the valve to the tank then the...
  9. weed78

    When does a welder become a WELDER

    For the fabrication of Pressure Equipment (to whatever Code) what knowledge does a welding operator need in order to be considered a Qualified Pressure Welder? A) Can turn a machine on and knows which button to press? B) Can adjust the machine so that a weld is produced? C) Can melt metal? D)...
  10. weed78

    Cryogenic Treatment of Materials

    I tried this posting in the Cryogenic Engineering forum but received no replies so I will ask my question here. Is there a significant difference in the final wear properties of tool steel materials cryogenically treated in liquid vs vapor?
  11. weed78

    Cryogenic Treatment of Materials

    Is there a significant difference in the final wear properties of tool steel materials treated in liquid vs vapour?
  12. weed78

    CRN Numbers do they apply to Pumps

    Pumps are not specifically addressed as a pressure component in CSA-B51 so therefore, by default ,the rules of Sect. VIII Div. I apply. As such the pump is exempt from being a pressure component, and therefore not requiring a CRN, as per U-1(c)(2)(c).
  13. weed78

    Cryogenic Engineering Companies

    Why does it need to be a small company? The large industrial gas guys are quite innovative. One small one you can check with is: www.fultonengineeredspecialties.com
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