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Recent content by shaff

  1. shaff

    Pressure Balanced Lubricated Plug Valve

    Can anyone give some clarification on the below statement with respect to plug valve design, In a discussion, it came up as "A pressure balanced plug valve has to be a lubricated metal seated plug valve" which logically means, "Soft seated plug valve cannot be pressure balanced?" Appreciate...
  2. shaff

    Design Conditions for Stress Analysis

    Hello, I am having confusion with respect to temperatures which I need to select for a pipe stress analysis. Do I have to consider the Minimum Design Temperature (zero DegC) for stress analysis or is it enough to take only installation temperature (21degC). My temperatures conditions are T1...
  3. shaff

    Valve Seat Design

    Hi, I have 2 doubts with regards to valve seats 1. What is the meaning of this statement "The ball and metal seat ring assembly shall be part matched by lapping". It would be great if you could guide me to some technical article or paper. 2. What is Primary Metal Secondary Soft (PMSS)...
  4. shaff

    Pipe Sleeper on Sloping Line

    Is it advisable to provide pipe sleepers on sloping lines? I have a 12" header rolling 9 degree vertically and a sleeper is shown in the drawing. Wondering if it is a good engineering practice. Any suggestions?
  5. shaff

    Elevation of PSVs in Plants

    Hi, I have observed this in all the site visits I have done. Top most thing in any train of piping is a PSV. It takes the highest elevation above the pipe rack. What is the logic? I do not want to get into hydraulics of it, but a basic logical reason to quench my curiosity. Thanks
  6. shaff

    Surge Analysis of Fire Water Piping

    I have filled the checklist for the surge analysis and have told the GRE pipe manufacture to have a go at Surge Analysis and provide supporting as applicable. :) Difficult part still remains - Convincing the Project Manager technically [pipe] whos always interested in numbers Thanks to all the...
  7. shaff

    Surge Analysis of Fire Water Piping

    Theory part: What are the conditions under which a surge analysis of a piping becomes necessary? What is the basis of surge analysis? What are we checking and trying to achieve by doing surge analysis of a piping section or a piping system? Coming to the practical case: There is an existing...
  8. shaff

    Volume of Nitrogen for Leak Testing

    I need to leak test a 10" - 100 meter long pipe at 20 Barg with Nitrogen What is the volume of nitrogen required for this leak test. Any calculation basis will be much helpful Thanks shaff
  9. shaff

    ASTM specification for Washer

    A bit progress.. F436 - Specification for Hardened Steel Washers , carbon steel, steel, washers, weathering steel, Hardened steel washers F844 - Standard Specification for Washers, Steel, Plain (Flat), Unhardened for General Use Which of these I can go for? What is the difference b/w Hardened...
  10. shaff

    ASTM specification for Washer

    Hello, What is the ASTM specification for washer to be used with A193/A194 bolting? Will ASTM A36 do the job? It will be used in GRE piping application. Service - Fire Water at moderate pressure and atmospheric temperature (85DegC design temp) Thanks
  11. shaff

    AISI 410 Vs 420

    Hello, Can we use AISI 420+stellite instead of AISI 410+stellite? This is for valve trim materials (Disc, Stem, Wedge, seat rings etc) Preliminary search on this says that they are same material with different strengths. 420 has higher carbon content. Corrosion resistance is same for both...
  12. shaff

    Incoloy Material Specification for Flanges

    denlow60 & XL83NL, Yes, you guys are right. it is ASTM B425 and B564 Typo from me... or rather we are so used to say A105, A106, A182... etc.. :)
  13. shaff

    Incoloy Material Specification for Flanges

    Hello All, Good Day..! I need to order an Incoloy flange. I have a very old piping class given to me and that says it is ASTM A425 (which is in the form of rod and bars). There is another grade, ASTM A564 (which is forging). While comparing I found chemical composition and mechanical...
  14. shaff

    Gate Valve Trim Materials

    Thanks gerhardl..! A bit of reading the Avenor's book and internet search has brought me to this conclusion, AISI 410 is a matensitic steel which is covered in many specifications, F6 is a grade of ASTM material spec A182 which is basically AISI 410 steel with specific heat treatment...
  15. shaff

    Gate Valve Trim Materials

    Hi, We need to procure gate valves for our project and I am doing Technical Assessment of Valve materials Datasheet given by design engineer asks for AISI 410 STELLITE COATED material whereas vendor is offering F6+STELLITE. Is this change acceptable? Valve will be working in moderate...

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