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  1. JustinME

    Does saponification of beeswax yield glycerin?

    I am making a custom grease (castor oil & sodium stearate) that will be suspended in beeswax. I have found that saponifying some beeswax for use in the grease results in higher operating temperatures after the grease is melted with the wax. I cannot have any glycerin in the final product, so I...
  2. JustinME

    ASME BPVC VIII Div 1 Max Allowable Stress

    If you start a fatigue test with a sample stressed at YS, you will find that the part fails at a fairly low cycle. If you test another sample at 90% of YS, you will find a greater cycle count to failure. If you repeat that sequence using incrementally lower values of stress, you will find that...
  3. JustinME

    ASME BPVC VIII Div 1 Max Allowable Stress

    I say this for the sake of completeness and for any future readers... not to be confrontational. It may come across that way, but that's not the purpose. The UTS requirements safeguards against a burst failure, and the YS requirement safeguards against a low or mid cycle fatigue failure. The...
  4. JustinME

    ASME BPVC VIII Div 1 Max Allowable Stress

    Thank you cbPVme & metengr. I was not aware of the 67%YS requirement. That fully satisfies my curiosity:)
  5. JustinME

    ASME BPVC VIII Div 1 Max Allowable Stress

    Thanks David. I'm not so concerned about WHAT the max allowable stress is. I am curious as to WHY the max allowable stress is what it is. Why base the max allowable stress on UTS and not YS?
  6. JustinME

    ASME BPVC VIII Div 1 Max Allowable Stress

    I have a copy of the BPVC VIII Div 1, and a Professional Engineering study book. I can use these two to calculate minimum allowable pressure vessel thickness. However, I have not found what the ASME max allowable stress is for a broad range of materials. Searching the internet, I have found a...
  7. JustinME

    How does a telltale hole fail in a pressure vessel?

    Thanks LittleInch. This air receiver will be sold into an application where it will be used by folks without a high school education. I have no control over whether or not inspection occurs, and I have no confidence that the end user is competent to conduct inspection. I have an expiration...
  8. JustinME

    How does a telltale hole fail in a pressure vessel?

    Thanks TGS4. Thank makes a lot of sense. I'm actually laughing at myself right now [smile].
  9. JustinME

    How does a telltale hole fail in a pressure vessel?

    Thanks rww88. I am investigating the TTH that does not fully penetrate the tank, and is used as an early indicator of excessive corrosion. I am not referring to a TTH that is used for testing, which is later plugged. Why does the ASME code state that the TTH should be placed opposite from...
  10. JustinME

    How does a telltale hole fail in a pressure vessel?

    Thanks again NBrink. UG25(e) of the ASME BPVC Section VIII provides sizing and positional guidance for the TTH. I imagine that if a fatigue failure did occur at the TTH, the significantly increased material thickness immediately around the TTH should still result in a safe failure mode. In...
  11. JustinME

    How does a telltale hole fail in a pressure vessel?

    Thanks NBrink. The application I am concerned with is the case where residential construction crews use an air receiver to increase the stored air capacity on their jobs sites. The stored air is primarily used to power a pneumatic tools. I would be surprised if any of these folks ever conduct...
  12. JustinME

    How does a telltale hole fail in a pressure vessel?

    Thanks everyone!
  13. JustinME

    How does a telltale hole fail in a pressure vessel?

    Hi LitteInch, I am referring to a telltale hole in the wall of a pressure vessel. I do not know what a repad is, but I do not think that repads exist in my application. I am not sure if I am allowed to directly quote the ASME spec on this forum, due to copy write issues. However, as I read...
  14. JustinME

    How does a telltale hole fail in a pressure vessel?

    I am referring to section UG25(e) of the ASME BPVC Section VIII, where dimensional details of telltale holes are described. I am investigating the value that a telltale hole can provide when integrated into a pressure vessel containing air below 200 psig, temperatures between -40 °F and 120 °F...
  15. JustinME

    Single Phase Induction Motor, Capacitor-Start Capacitor-Run Equivalent Circuit Diagram

    I cut the wires to the capacitors so that I measured the inductance for each coil without the capacitors in the circuit. Is there any known relationships for the magnetic permeability for steel? If so, then a scalar could be identified by dividing mu for very low current over mu for very high...
  16. JustinME

    Single Phase Induction Motor, Capacitor-Start Capacitor-Run Equivalent Circuit Diagram

    I have created a circuit diagram for a single phase CSCR induction motor, but only for the purpose of calculating start-up current (i.e. motor speed is at, or very near, zero RPM). I have created this diagram because: 1) I do not have the tools & knowledge required to generate the Steinmetz...
  17. JustinME

    Impact Force, Cantelever Beam, Elastic

    rb1957 - I see two phase shifts, so I'll address them both. Phase shift at beginning of data: The accelerometer outpust data slightly before the force gage, and I do not believe the time shift is reasonable. The point of impact is the point where the force is measured (well, there is a two...
  18. JustinME

    Impact Force, Cantelever Beam, Elastic

    IRstuff - The force is measured at the bottom of the caster wheel. The caster is colliding with the force gage. The acceleration is measured on top of the steel plate to which the caster is mounted, directly over the caster swivel bearing axis. The force is measured with a strain type...
  19. JustinME

    Impact Force, Cantelever Beam, Elastic

    rb1957 - the acceleration vector is shown only to communicate the direction in which acceleration is being measured. In oher words, I have a single axis accelerometer measuring in the direction parralel to the caster swivel axis.
  20. JustinME

    Impact Force, Cantelever Beam, Elastic

    Also, the machine contains 10 gallons of water that sloshes around immediately after the impact which may cause some of the oscillations seen in the four plots above.

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