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Recent content by John3p

  1. John3p

    When is a reduced port ball valve a better choice?

    bcd, Wow! What an excellent explanation. You've not only clarified a long standing question I've had, in doing so you've also enabled me to be better at my job. Although 80% of the ball valves I spec' and purchase must be piggable and minimize energy loss, the cost savings of installing...
  2. John3p

    The sealing forces by ball valves

    With trunnion mounted ball valves, you'd need some info from the manufacturer. But with floating ball valves it's simply a function of the pressure differential on either side of the ball. Apply the delta-P to the effective cross-sectional area of the ball's upstream side to figure the force...
  3. John3p

    When is a reduced port ball valve a better choice?

    TBP, Thanks for providing some applications where reduced port ball valves are commonly used. I can understand how the reduced port style might be less expensive in smaller sizes, especially if the manufacturers are using the same casting for both types of balls and simply machining a larger...
  4. John3p

    When is a reduced port ball valve a better choice?

    Having been in the industry over 8 years, I'm almost embarrassed to ask, but it's something that been bugging me: Considering that pressure/energy loss is almost always undesirable, and the fact that they're not easily pigged, why and under what circumstances would a reduced port ball valve ever...
  5. John3p

    Coeficient of friction?

    Coefficients of friction are determined empirically. You must specify the other material with which the Incoloy is in contact. Also, surface profiles (smoothness) and conditions (wet, dry, lubricated, etc.) must be considered. Additionally, static (starting from rest) and dynamic (maintaining...
  6. John3p

    won't print text

    Although it's costly, if you're working with a large drawing you might try adding some more memory to your printer. A well defined problem is half solved.
  7. John3p

    Strength in slotted pipe

    I got so wrapped up in the fundamentals that I failed to address your question: >My question is, many slots pr. ft could I make to keep the >same compression and tensile strength in this casing joint? Answer: It is impossible to remove portions of the pipe and keep the same tensile strength...
  8. John3p

    Strength in slotted pipe

    With steel, yield strength in compression and tension will be virtually equal. The strength of the pipe itself is a function of the material's yield strength and the pipe's cross sectional area (assuming straight, constant diameter pipe). If you reduce the area in any way (i.e. decreasing wall...
  9. John3p

    Project Management: Whats most troublesome?

    One of the most troublesome aspects of the projects I manage is incomplete specifications. If the clients would spend the same time and energy specifying complete design conditions and scopes of supply as they do preparing contracts designed to indemnify themselves against any and all...
  10. John3p

    ASME Fasteners Vs SAE Fasteners

    TPB, Thanks. I'll look into acquiring that little IPT book. A well defined problem is half solved.
  11. John3p

    ASME Fasteners Vs SAE Fasteners

    Interesting question. I'm not sure what we can infer from this, but the Machinery's Handbook lists identical head markings for: SAE - Grade 5 & ASTM A449 SAE - Grade 8 & ASTM A354 Grade BD I'd be interested in a more definitive answer. A well defined problem is half solved.
  12. John3p

    ASME SEC II, ALLOWABLE STRESS VALUE, HELP!!!!!!!!!

    Tom, I believe Appendix 1 of II-D provides the explanation for the two different stress values. A well defined problem is half solved.
  13. John3p

    ASME SEC II, ALLOWABLE STRESS VALUE, HELP!!!!!!!!!

    Falco, I do not find a listing for 18% Cr 9% Ni in the tables. However, there is a listing for 18% Cr 8% Ni Type 304 Steel Plate: Max. Allowable Stress @ 500°F = 12.9 ksi A well defined problem is half solved.
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