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  1. TomaszKruk

    Vapor pressure, negative gauge pressure in a pipe, air bubbles - question about good design practice

    Hello, I've received incomplete demand data, and the velocities need not to be that low. Problem solved. The nagging feeling of impending doom approaching - receds. Thank you both :)
  2. TomaszKruk

    Vapor pressure, negative gauge pressure in a pipe, air bubbles - question about good design practice

    Thank you both. Gonna read up on the matter, check the lines on the site, and consult with the guys actually using the systems.
  3. TomaszKruk

    Vapor pressure, negative gauge pressure in a pipe, air bubbles - question about good design practice

    Hello, Honestly the question comes from me not having the leg of design guideliness to stand on. I wanted to confirm that negative gauge pressure is not bad, as long as it doesn't reach vapor pressure of the liquid. I come from water systems, where high points are bad for warm water, and...
  4. TomaszKruk

    Vapor pressure, negative gauge pressure in a pipe, air bubbles - question about good design practice

    Hello, I feel really dumb to be confused by this, but I started to work with liquids other than water and this whole vapor pressure thing seems to go against my previous practice. First of all - I work mostly with pumping either industrial sewage or water from surface intakes. What it meant...
  5. TomaszKruk

    Force main bypass into gravitatinal flow - how to discharge 3 bar (industrial sewage)

    Post just for the other diagram - cannot make multiple images work for this forums atm - sorry. https://files.engineering.com/getfile.aspx?folder=7e5240e2-2123-4103-8b80-e49475baf991&file=diagram__-_new_line_replacing_existing_by-pass.png
  6. TomaszKruk

    Force main bypass into gravitatinal flow - how to discharge 3 bar (industrial sewage)

    hello, thanks for the answer. I drew 2 diagrams that might be helpful. Hope they're clear enough. When it comes to elevation - it's pretty much an insignicifact slope down to the river. The change of elevation is small - no hills or depressions, just a gentle slope down to the river. All pipes...
  7. TomaszKruk

    Force main bypass into gravitatinal flow - how to discharge 3 bar (industrial sewage)

    Hello, the customer has a pumping station with a force main and second pipe acting as gravitational bypass. Gravitational line works 24/7 - it allows them to discharge a fraction of the sewage without it going to pumping station further down the line so they use it. I'm to redesign the...
  8. TomaszKruk

    Pressure drop in compressible flow

    Thank you for your input. I should come back to pressure loss soonish (I hope)- all the post will be of great help then. Calculating same values with different equations will allow me to verify results and learn the ropes. Cheers!
  9. TomaszKruk

    Pressure drop in compressible flow

    thanks for all the answers guys. I understand a bit more now.
  10. TomaszKruk

    Pressure drop in compressible flow

    Hello, thanks for the answers. I got a pressure drop of around 0,26 bar (a) using the mass flow equation. When it comes to "Y" factor - I meant an equation I found this in Crane: w = 1.111 x 10^(-6) x Y x d^(2) * (dp / K / V)^(1/2) where V is specific volume of fluid. The Paper is dated so...
  11. TomaszKruk

    Pressure drop in compressible flow

    Hello guys, thanks for answers. Especially nice to see LittleInch here who I remember helping me last year (I think with water flow, which I managed to get a handle of in the end - thanks!). Pure Oxygen 33 000 Nm3/h Iso pipe 219,1 x 8 mm 41,5 bar (a) compressor working pressure 321 ANSI...
  12. TomaszKruk

    Pressure drop in compressible flow

    Hello, I have a problem to solve that seemed trivial at first, but kinda got out of hand quickly. I want to properly calculate pressure drop on a gas pipe on a chemical plant. I thought I'd find "plug and play" equations with iterations maybe, but after 2 days of reading I'm horribly confused...
  13. TomaszKruk

    Material compatibility for oxygen service

    hello, I have a question about resources evaluating piping material compatibility for oxygen service. We are using EIGA documents, but they recommend Inconel / Monel / Hastelloy for pressures above 4,0 MPa. And that's it. I was hoping to find some data regarding possibility of using stainless...
  14. TomaszKruk

    Self passivation of Stainless Steel 316L - questions

    Thanks for all the answers. Maybe I will be able to post something done by our guys soonish.
  15. TomaszKruk

    Self passivation of Stainless Steel 316L - questions

    It's a bit dumb to ask the questions, since there's no conclusions to be drawn, but maybe you guys can look at this weld and tell me what it looks like to you. The pipe was installed on what is supposedly very high quality water (everything is vague, sadly). We're required to provide much higher...
  16. TomaszKruk

    Self passivation of Stainless Steel 316L - questions

    Both posts are great. Thanks for explaining this stuff.
  17. TomaszKruk

    Self passivation of Stainless Steel 316L - questions

    Thank you for our answer. How does weld surface behave, though? Does it self passivate? If I understand your post correctly - it does self passivate, but the weld surface remains somewhat vulnerable to corrosion, if right (or wrong), particular conditions happen. I think they chill their...
  18. TomaszKruk

    Self passivation of Stainless Steel 316L - questions

    hello, kinda newbish questions, but the specific answers are hard to come by from what I could google. Hope someone will take time to answer them. 1) I'm currently on a job, when we are to modify an existing demi water installation. Having removed some pipes I noticed signs of oxidization on...
  19. TomaszKruk

    Concrete underground tank - safe pressure at inlet?

    1) That's what I meant 2) thanks - that's what I wanted to know. 3) Thanks! Those are low in my pipe. Can you reccomend what to read to get more into this? 4) N/A 5) That's what I meant. I will forward your info about coating. We did consider it but someone decided against it. I will try to...
  20. TomaszKruk

    Concrete underground tank - safe pressure at inlet?

    Thanks for the answer. And yeah - I'm inexperienced so it might be the reason why I'm worried about stuff I should not be. 1) When it comes to manufacturers - the practice here is to make the manufacturers select the pumps. The designer gives them working points, and they themselves figure out...

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