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  • Users: howkers
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  1. howkers

    Drip drip drip

    Occasionally our maintenance engineers report leakage in drips per minute. Fluid is water at various temperatures. I'm guessing the droplet size is related to viscosity and surface tension properties at different temperatures. Has anyone got a link to an estimate of typical water drop size at...
  2. howkers

    Calculation of female thread strength

    A colleague in Sweden is in the process of designing a new flange joint bolted together with bolts (M30 to M100). Current calculation methods within the department are 10+ years old and are limited to typically 45% of the yield stress of the bolt shank, this limitation is due to the stripping of...
  3. howkers

    [b]Spring Torsional Stress[/b]

    I was asked to check the torsional stress in the wire of a spring and plugged the numbers into the standard equation from the text books: shear stress = (8 x load x mean diameter x w-factor)/(pi x wire-diameter cubed) I was surprised to get a result which exceeded the shear ultimate stress for...
  4. howkers

    Surface finish for thermal shock cracking

    We manufacture nuclear valves to ASME III. Some of our older designs have surface finishes on internal surfaces of 16 micro inch, which is hard to achieve. It has been suggested that this was introduced to prevent cracking due to thermal shock and that this was derived from a requirement in ASME...
  5. howkers

    Reliability data for valves

    I have a project to find reliability data for valves in nuclear power plants. Can anyone advise me of sources of such data. I have started to work through some of the sources listed in the following site: http://www.risoe.dk/rispubl/sys/ris-r-1235.htm Bill
  6. howkers

    Reliability data for valves

    I have a project to find reliability data for valves in nuclear power plants. Can anyone advise me of sources of such data. I have started to work through some of the sources listed in the following site: http://www.risoe.dk/rispubl/sys/ris-r-1235.htm Bill
  7. howkers

    Reliability data for nuclear valves

    I have a project to find reliability data for valves in nuclear power plants. Can anyone advise me of sources of such data. I have started to work throughsome of the sources listed in the following site: http://www.risoe.dk/rispubl/sys/ris-r-1235.htm Bill
  8. howkers

    Stellite seats on steam relief valve

    I am having trouble with erosion damage to a relief valve pilot seat from wire drawing in a steam application. The Stellite 6 seat is tapered and gives contact at the top edge. The poppet is of Stellite 12 at slightly shallower angle, about 60 degrees inclusive. I have been advised that...
  9. howkers

    Stellite seats for steam relief valve

    I am having trouble with erosion damage to a relief valve pilot seat from wire drawing in a steam application. The Stellite 6 seat is tapered and gives contact at the top edge. The poppet is of Stellite 12 at slightly shallower angle, about 60 degrees inclusive. I have been advised that...
  10. howkers

    Galling - Stellite 6 self mated pair

    The usual loaded pin galling pressure test runs at relatively low surface velocities. I am told by one of our valve suppliers that they had extensive difficulties with self-mated Stellite 6 in water when the operating speed of the valve was increased to slightly over 1 ft/sec. Below this it was...
  11. howkers

    Galling - Stellite 6 on Stellite 6

    The usual loaded pin galling pressure test runs at relatively low surface velocities. I am told by one of our valve suppliers that they had extensive difficulties with self-mated Stellite 6 in water when the opeating speed of the valve was increased to slightly over 1 ft/sec. Below this it was...
  12. howkers

    Cv and K values

    I work with systems engineers who use the Crane 410M book for resistance calculations using resistance coefficient K. First question is K dimensionless and the same value for calculations in US gallons/minte and litres/min. Second question. A lot of the valve manufacturers quote flow...
  13. howkers

    Bellows sealed valves

    I am doing some analysis on a relief valve with bellows sealed stem. What area do you take as the pressure area of the bellows? Is it internal/external or mean of the convolutions? TIA Bill
  14. howkers

    PWR Safety Relief Valves

    How frequently are PWR Safety Relief Valves tested? Are they generally tested in-situ or removed to a workshop? Are they tested on the operating fluid and temperature? Are there any code requirements relating to this?
  15. howkers

    Thermal conductivity of epoxy paint

    Has anyone ever seen an authoritative reference to the thermal conductivity of a typical epoxy paint used on marine structures.
  16. howkers

    Thermal conductivity of epoxy paint

    Has anyone ever seen an authoritative reference to the thermal conductivity of a typical epoxy paint used on marine structures.
  17. howkers

    Valve design text book

    I am an experienced mechanical engineer who has made a new start in the valve design side of my UK company within the last year, after 30 years experience on unrelated equipment. A former colleague sold me a text book on valve design. Being a sad geek I took it on holiday with me to read and...

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