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  • Users: shaff
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  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

    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...
  7. 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
  8. 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
  9. 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...
  10. 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...
  11. 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...
  12. shaff

    HIC and SSC testing requirements

    Hi all, I am in the process of evaluating bids for pipes to be used in a sour service. NACE MR 0175 is applicable for these pipes. Majority of vendors are stating that since they are supplying pipes with sulpur content less thant 0.01%, HIC test need not be done. Is this an acceptable...
  13. shaff

    Titanium spools connecting to Heat Exchanger

    Hey guys, Heat exchager is using seawater for cooling purpose. The which connect to the HE nozzles are of TITANIUM material. Then it continues as CS with serr glass flake lining inside. My question is why the TITANIUM spools in between, why not glass lined CS pipes all along? Also, I will be...
  14. shaff

    Strainer plate perforation

    Hello, In the data sheet for a strainer the specification for perforation is given as " For gas service: 7.2 holes/cm2, 3mm plate thickness." What exaclty this means? I presume that there is some lack of data in here... I need to give hole dia and pitch to the strainer manufacturer. How to...
  15. shaff

    Hydro test pressure exeeds the set value

    10" Sch 120 pipe is hydrotested at 165.45Barg pressure. The relief valve was set of 1.1 times this pressure (181.99Barg). However during test the pressure went upto 188 Barg. due to improper settings. Will this raise in pressure (188Barg) have any impact on properties of pipe material? Has any...
  16. shaff

    Weling on internally coated pipeline

    To construct additional Fuel supply - Hard stands for Aircrafts in a newly built airport, we need to take tapping from existing underground pipeline (20” API 5LB Sch40 pipe, internally coated). Tapping is done by a Weldolet 20”X6” on the pipe. Client mechanical engineer says that they will run...
  17. shaff

    ASTM specifcation for U-Bolts

    Hi, I have to specify a U-Bolt for a A106B pipe. My understanding is that U-Bolt materials are of same material as the Stud Bolt material specified for the flange (in the relevant pipe class). The difference here is that it is bent to U shape. Am I correct? I went throgh a lot of product...
  18. shaff

    A350 LF2 In Place of A105

    Hi, Pipe Class and the data sheet for a ball valve calls for A105 Body material. Project department has procured A350 Lf2 material Ball valve and asking engineering to give some justification to show to client that it is superior and hence acceptable for the servie (oil line at amb. temperature)...

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