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  • Users: dmertz
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  1. dmertz

    Mass Moment of Inertia

    I found a couple old threads on this topic: thread820-140933 thread407-23283 Neither seemed to answer the question regarding what GD2 vs. WR2 mean. The best answer I have found is that GD2 is what mass moment of inertia is called in SI units and it would typically have units of kg*m^2. WR2...
  2. dmertz

    Tapping hole through two welded plates

    I have two pieces of carbon steel A36 plate that were welded together to make a thicker plate. Is it acceptable to tap a hole through both of them at the same time to get the bolt thread engagement I need? Or should I replace with a single thicker piece of plate? Any concerns about corrosion...
  3. dmertz

    Centrifugal compressor hold down bolt design

    What is the best method for mounting centrifugal compressor feet to the baseplate supports? 1. Bolt threaded directly into threaded hole on the baseplate. 2. Through bolt with nut and washer on the bottom. The compressors I have seen use the bolt threaded directly into the baseplate...
  4. dmertz

    Compressor aftercooler cleanliness criteria

    API 661 does not mention any specific flushing/cleanliness criteria for air-cooled heat exchangers, in this case a compressor aftercooler. The only criteria it has is for the cooler to be "free of foreign matter." I understand that if the client has a specific cleanliness for their gas, that...
  5. dmertz

    Carbon steel 900# Orifice RTJ flange coating/paint

    A carbon steel 18"SCH40 900# orifice flange that we procured arrived coated with black paint. I am concerned that the coating will interfere with the RTJ groove on the flange. Is this a problem? Also, the inside of the flange will be exposed in the pipeline. Should I be concerned about...
  6. dmertz

    Closed loop pneumatically actuated valve operation

    A potential problem in one of our quick close valves was brought to my attention. During normal operation, the actuator to the main valve is held closed by an 80 psi instrument air line. Upon loss of air, the main valve is meant to close quickly by way of a quick exhaust valve (QEV)...

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