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  1. JohnGP

    Why is NPSH can not be determined if the suction is flooded (?)

    TenPenny, that may generally be the case, but the vendor in this case knows the product being pumped at ambient pressure and temperature. It is difficult to see that NPSHa would be something to be concerned with.
  2. JohnGP

    How to calculate Design Pressure?

    vinothsvk, you're mixing up gauge pressure with absolute pressure. Atmospheric pressure is 0 bar gauge (barg), and your design pressure is 0.309barg. Cheers, John
  3. JohnGP

    Centrifugal pump_Fire fighting system

    In my experience, most pumps have had a concentric reducer on the discharge side of the pump, per LittleInch's comment (and commonly an eccentric reducer on the suction side). But I don't see a problem with having an eccentric reducer on the discharge.
  4. JohnGP

    MAWP

    Internal tray supports are not part of the pressure boundary, so do not need a MAWP calculation performed. They do need to be designed to support loadings applied to the trays, but pressure forces should balance out.
  5. JohnGP

    Sec VIII Div 2... para 4.5 nozzle calculations formula derivation

    In the Les M. Bildy paper "A Proposed Method for Finding Stress and Allowable Pressure in Cylinders with Radial Nozzles" https://www.codeware.com/company/docs/PVP-399-Les-Bildy.pdf , the Background discussion more or less reiterates TomBarsh's explanation by stating "...the discontinuity stress...
  6. JohnGP

    design pressure, MAP, MAWP, hydrostatic test, horizontal vessel

    On reflection, use of PV code for receiver design may not be as common as I indicated previously. (I found a drawing from a previous project where the pipeline code was used for the pig trap designs). There should be no issue with receiver ID if the small barrel section is made from the same...
  7. JohnGP

    design pressure, MAP, MAWP, hydrostatic test, horizontal vessel

    LI, I'm not saying launchers/receivers should be designed as pressure vessels, just that I have seen it done that way. Obviously there are issues to be managed, and for high pressure stuff particularly, the small barrel section would need to be manufactured to suit the pipeline. The receiver...
  8. JohnGP

    design pressure, MAP, MAWP, hydrostatic test, horizontal vessel

    Design pressure should be set at least 10% above MOP, in my opinion, but should not be less than the pipeline design pressure. Hydrostatic test pressure should be the same as that set for the attached pipeline. The receiver can be designed as a pressure vessel (and is often done that way), and...
  9. JohnGP

    Flexible Coupling in Pump Suction

    To get back to the original query- Yes, I believe such an arrangement would be suitable, with the joints you originally proposed. You would need to support the straight run of pipe adjacent to each flexible joint, with supports incorporating integral height adjustment so you can follow the tank...
  10. JohnGP

    Flexible Coupling in Pump Suction

    In the system as described, I don't see internal or external pressure being a problem.
  11. JohnGP

    Pipe supports for Natural gas line

    Bolt-on type shoes have the advantage of not requiring hot work, which may or not be an issue in that particular plant.
  12. JohnGP

    Pipe supports for Natural gas line

    Pipelines tend to want to move a bit on supports, so any coating on the pipe will likely break down and lead to corrosion at the support points, as you have found. If the pipeline can be raised, one solution is to utilise bolt-on shoes, such as shown in -...
  13. JohnGP

    UG-36(g) vs. B16.9 - Eccentric Reducer Section

    The 2003 edition has that, but marking requirements have been revised between that and my 2012 edition (still current) Section 4 is all about marking requirements, and with the supplementary designations called up in para 4.4.2 for special fittings. You would need to confirm that the fitting...
  14. JohnGP

    Piping inside box culvert vs buried pipe

    It's all a bit of a guess without actual design data, but double containment will have an effect, but I don't think a "resounding" effect. After all it is basically another layer of "insulation" with low thermal conductivity. Concrete will have a similarly low thermal conductivity depending on...
  15. JohnGP

    Vessels on support legs

    I've also not come across a vessel where the nozzle loads had a significant effect on support design. The difficulty with including nozzle loads in the support design is that piping connection loads are not generally known at the outset, and as noted above, the loads generally counteract each...
  16. JohnGP

    Preheat Requirement

    For P-1 material between 32mm and 38mm thick, the exemption on preheat only applies to SA-841 Grades A and B. i.e. for SA-516 Gr70 (and other SA-516 grades) in this thickness range, you would need to postweld heat treat unless you undertake preheat to 95oC during welding.
  17. JohnGP

    Field Pump Performance Test

    Provided you have means to measure flowrates and pressures, you can check whether a pump has moved off its curve, preferably by recording the flow at a few different pressures. Pressure readings need to be adjusted back to pump centreline values, and adjustment made to the target values to...
  18. JohnGP

    Vibration Analysis of Barred Tees

    Vibration analysis of branch connections is usually performed if acoustic induced vibration (AIV) or flow induced vibration (FIV) is likely to be an issue. A good starting point would be "Guidelines for the Avoidance of Induced Fatigue Failure in Process Pipework" produced by the Energy...
  19. JohnGP

    Explosive Cladding requirements

    In addition to above, the vendor should be able to provide their weld procedures and methodology. Not sure what cladding you have, but usually welding of joints is done with batten strips of the same material (i.e. titanium, zirconium, tantalum), after welding of the carbon steel plate is completed.
  20. JohnGP

    high Amps on newly replaced pump

    You need a copy of the pump curves to check where the previous pump was operating and compare to the new pump. It could be this pump is operating further out on the curve, as Artisi suggests, thereby consuming slightly more power. Bit hard to tell without all the facts.

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