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  1. JG MechEng

    Yield stress of 9 chrome at 1375 deg F

    Strait 9Cr I spoke with a buddy of mine that is a metallurgist and another one from a separate client..between them two and the responses I’m getting here…sounds like a no no! Thanks to all for the comments!
  2. JG MechEng

    Yield stress of 9 chrome at 1375 deg F

    I have been asked by a client to rerate heater tubes to 1375 deg F and 890psi. Spent a fair amount of time trying to find yield strength data for 9 chrome at that elevated temperature. Also, API 530 larson miller parameter tables stop at 1300 deg F. Looking for some guidance on locating...
  3. JG MechEng

    Steel stack design for elevated temps

    I dont have much experience in stacks need some help. I have a client that has asked me to develop some thicknesses for a few stacks and they are specified to be made from A242 and the design temp is 750°F. Stack has no insulation and no refractory and the datasheet does not specify any liner...
  4. JG MechEng

    HVAC Design

    @MintJulep - There are some special circumstances to why I'm taking on the project, but if I were following normal working procedures...I agree with you...stay in my area. But that's not where I'm at so I'm reaching for help! I also know that there is not a standard for "Electrical Substation...
  5. JG MechEng

    HVAC Design

    @Willard - I dont fully agree that its unethical. outlining the design parameters and letting a vendor design the system is common in the petrochem industry and is often preferred. Liability is only with the sealing engineer and i wouldnt be sealing it if the vendor does the design...BUUUT...I...
  6. JG MechEng

    HVAC Design

    Hi everyone, I have been asked to design an HVAC system for an electrical substation. I am a mechanical engineer but my experience is in process equipment design so I am way out of my area of experience. I know that ASHRAE is the design code for HVAC systems, but I'm not sure specifically...
  7. JG MechEng

    Confused about thermal conductivity units

    @IRstuff - thanks for writing it out...I was making it more complex than.
  8. JG MechEng

    Confused about thermal conductivity units

    I think you are having trouble seeing my issue because it is most likely EXTREMELY TRIVIAL...I cannot find any evidence that supports the units of thermal conductivity to be Btu/sec/in/deg.F as the software documentation states except for this one site (...
  9. JG MechEng

    Confused about thermal conductivity units

    I am setting up a steady state thermal analysis of a model. I am using FEPipe and the help file says this... "For steady state or transient the thermal conductivity is a required input. If this value is omitted, (as it often is), the user will get unpredictable thermal solutions. The standard...
  10. JG MechEng

    Vertical stiffener to resist buckling

    Here is the situation: API 650 (new construction) open top clarifier tank (98' diameter x 35' tall) There is a complex platform and walk way that is supported by the shell and a center tower structure In one area of the shell, additional aeration boxes are also being supported. This is putting...
  11. JG MechEng

    Damaged flange facing - should this get repaired or replaced

    The scar is about 1/8" deep. Pcc-2 says I can leave 1/32" raised face and still claim it to be a raised face. We also have a contractor on site that has equipment to do this precision work in the field without weld metal build up. Thank you for the replies. I plan to have the raised face...
  12. JG MechEng

    Damaged flange facing - should this get repaired or replaced

    While it may be rather strange, it is an option and is also permitted to be ordered in that configuration per B16.5. It was just intended to point out that the raised face is not considered to contribute to the flange strength so it seems that the height of the raised face could be considered...
  13. JG MechEng

    Damaged flange facing - should this get repaired or replaced

    Situation: 4" 1500# equal barrel flange (SA-350 LF2 Cl. 1) on the channel of an PWHT'ed exchanger that has a scar. The depth is about 1/8" and the raised face thickness is 1/4". I am wondering what the options are for repair, and what everyone things about the options i have listed below...
  14. JG MechEng

    Metal Expansion Joint

    I believe the vendor develops the stiffness with a combination of FEA and or EJMA calculations. The vendor will need to know the allowable expansion joint travel in each direction. This is some times identified in client specifications and if not, you will need to work with the vendor for a...
  15. JG MechEng

    Hydro Testing of Trim Valves on Equipment

    Would you guys do a B31.3 hydro test on trim valves on equipment that we are not planning to use at this time. They will be blinded off for use as a future tie point. The valves come from the manufacturer with a hydro, but only for a few seconds at flange rating. I would think we would not...
  16. JG MechEng

    The use of SA-479 bar for pressure parts in ASME VIII Div.2 construction?

    You are correct, I was looking at the 309H.
  17. JG MechEng

    Atmospheric pressure vessel in PVElite

    Depending on your requirements, you may not be able to use API 650 calculation. If you need to have a name plated vessel, you will be required by the AI to use the ASME code calculation. Confirm if you are in a state where ASME Section VIII is law, and when you start mixing standards, it opens...
  18. JG MechEng

    The use of SA-479 bar for pressure parts in ASME VIII Div.2 construction?

    Table 5A is for Div 2 materials and it is listed and allowable stresses are provided so that would imply that is is acceptable material. Note G2 says it is not recommended for flanges and other things where leakage is a possibility (although this may not apply, see below). I would consider...
  19. JG MechEng

    Thickness of cylidrcal shell under external pressure

    When calculation thickness for external pressure, the only length that matters is the calculated effective shell length. This is the max allowable unsupported shell can length; this value may be longer than the individual shell can lengths. No credit or penalty is taken for circ seams. This...
  20. JG MechEng

    Support Leg and Base Plate Analysis

    I am not sure exactly what part of the analysis you are having trouble with, but I would use ASCE (or the EU equivalent) to develop the wind and seismic loads. These loads can be added in manually if the software will not compute the loads to the standard you are wanting to use. WRC or FEA can...

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