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  1. davefitz

    Trying to determine airflow through a pipe when vacuum is applied

    The device referred to is commonly called an "eductor", many designs are available on line with calculation procedures. I would first refer to Perry's handbook, but if not there, then an online search under the tag eductor should result in the design method and also vendors .
  2. davefitz

    Heat exchanger in hydrogen service

    Nearly all electrical generators above 250 MWe capacity are hydrogen cooled- I would contact those manufacturers, and also read and follow the safety guideliness developed by NASA for hydrogen service.
  3. davefitz

    Material to outlive the Giza Pyramids

    well, you could duplicate the method used to form the pyramids. It has been proven that all the interior blocks were formed of geoplymer concrete. See tech papers at <www.geopolymer.org>
  4. davefitz

    Thermal stress at circumferential weld, acceptance criteria

    KevinNs Yes, that is true, except the ASME code does not require it. Unfortunately a design engineer straight out of college often does not have such insight and so such errors get into the field and cause failures. "...when logic, and proportion, have fallen, sloppy dead..." Grace Slick
  5. davefitz

    Boeing again

    Here is the 1979 NRC letter that summarizes the need to shutdown and retrofit the earthquake dynamic piping supports at east coast nukes. It occurrred shortly after TMI and this concern was noted by none other than the USA president J E Carter. This may be one example of appointing an engineer...
  6. davefitz

    Boeing again

    I seem to recall that there was an error in the engineering fomulations of the stress in piping components that caused half of the US nuclear plants to be shutdown and retrofit back in the late 1980's. A US NRC nuclear reg commission field engineer / inspector saw that the dynamic earthquake...
  7. davefitz

    Boeing again

    In my 45 yr career I've seen 4 companies effectively become dissolved due to poor management changes. Boeing appears to have all the same management issues as those 4, and the only thing that allows them to hang on is their "crony capitalism" ties to the gov't regulators, legislators, and...
  8. davefitz

    Miami Beach, Champlain Towers South apartment building collapse, Part 19

    A similar sort of condo conundrum is playing out in Honolulu,Hawaii, but without the consternation that developed in Florida. Perhaps 20 years ago the US supreme court ruled that the hawaiian rules which mandated that only native hawaiians could own the land under properties was struck down...
  9. davefitz

    Boeing again

    Kinda reminds me of a 1960's TV show , where the actors are stranded on an island for 3 months instead of a " 3 hour tour". "...when logic, and proportion, have fallen, sloppy dead..." Grace Slick
  10. davefitz

    Miami Beach, Champlain Towers South apartment building collapse, Part 19

    Here is a link to one of the few companies that sell geopolymer stucco in the USA: https://www.geopolymertech.com/st200-stucco/. It has much lower porosity than portland cement stucco and might achieve adequate mitigation against chloride corrosion to the embedded rebar. "...when logic, and...
  11. davefitz

    Socket welded fittings vs Butt welded fittings

    GD2- actually there are a few niche applications for orbital welded SS tubes in the HRSG ( heat recovery steam generators)industry . The canadian company IST makes a once thru steam generator using small diameter incolnel tubes that are attached to stubs on the inlet and outlet headers using an...
  12. davefitz

    Thermal stress at circumferential weld, acceptance criteria

    I have witnessed prompt low cycle fatigue failure due to thermal stress on high energy piping at USA electric power plants, when welding thin wall P91 HP main steam pipe ( 1.5" thk) to 2.25Cr stop valves that have about 50% of the P91 allowable stress at 1050F, and therfore are over twice the...
  13. davefitz

    Socket welded fittings vs Butt welded fittings

    TugBoatEng is correct, but there have been developed automated machines ( orbital welders) that can be used for small diameter SS tubing , originally developed for aircraft but applied to Heat Exchanger tubing as well. There could be clearance issues to allow the machine's components to fit...
  14. davefitz

    Miami Beach, Champlain Towers South apartment building collapse, Part 19

    AS you would expect, Florida pased new laws and regulations that now require the condos within 6 miles of the ocean have routine inspections and require the condo HOA's to provide sufficient cash reserves to implement all fixes that are recommended by the inspectors. Those requirements have led...
  15. davefitz

    Cavitation Erosion Particle Size

    The cavitation occurs when the local pressure drops below the saturation pressure . The items that cause the pressure to drop to that low level downstream of the filter are related to the filter pressure drop which in turn varies by the square of the flowrate . If the flowrate varies depending...
  16. davefitz

    PWHT technical resources (course / notes)

    There are some practical guidelines that need to be followed which are not immediately obvious. Most of these guuidelines are in the code AWS D-10 and some papers by the commercial outfit Superheat. These include the need to locate the monitoring thermocouples as close to the weld line as...
  17. davefitz

    Cyclone Separator Design Question

    There was a great deal of technical papers describing the performance of such separators used in CFB circulating fluidized bed boilers in the time period 1990-2000. Review the ASME published tech papers from the power conferences of that period. Another reference that started it all is...
  18. davefitz

    Built on Wrong Property

    I seem to recall browsing thru an old book on surveying, and in the good old days the reference point a surveyor would use is a bottle top nailed to an oak tree. Such a refernce point would at least last thru the career of the surveyor, and as with all of us, what happens after retirement is...
  19. davefitz

    Failure analysis of a thin-walled tube

    Well, at a sharp interface between a thin and a thicker tube has at least 2 different failure modes besides corrosion. In the case of mechanical fatigue, pipeline stresses will preferentially fail at such an interface.Typical examples are a pipe size reducer located next to a control valve and...
  20. davefitz

    Steam flow rate calculation for boiler piping &amp; PRV valve

    Your local boiler code should have instructions on sizing and placing a pressure relief valve, usually called a safety valve. A boiler's safety valve needs to be installed in direct communication with the steam drum and not downstream of an outlet pressure reducing valve. The sizing of the...

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