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  1. koshyeng

    Vapor phase concentration

    I used activity coeff. with UNIFAC models. Is it right to say since total vapor pressure is less than system pressure, there will be no vapor phase? This is an open pit, so I believe I need to look into calculating evaporation rates of mixtures. Any guidance or reference for determining...
  2. koshyeng

    Vapor phase concentration

    Is raoults law valid for very low concentration of solute in aqueous solutions? I have 9000 ppm (w) of Acetone in Water and I am trying to determine vapor phase concentration of Acetone at 120F and 760 mmHg. So I converted in to mole fractions ( Xac: 0.00046 and Xwater: 0.9996) With pure vapor...
  3. koshyeng

    Use of Composite materials to alter ASME pressure vessels

    metengr, Composite material is CFRP. The thickness of the material and the grade selected upon engineering calculations will be equivalent to our current material and pressure ratings. jte, Thanks for your response. I am least inclined towards this approach but I was asked to evaluate this...
  4. koshyeng

    Use of Composite materials to alter ASME pressure vessels

    Dear experts, ASME PCC-2 is a post construction code for vessel repairs and alterations using composite materials. I need to repair cracks in of our pressure vessel and composite materials using PCC-2 code will improve the vessel integrity with minimum risk. NBIC inspector, who will be...
  5. koshyeng

    Motor Stator failure

    Thanks guys. Will get the vendor to do additional tests on the windings and inspect while we pull out the strands at the motor shop. One thought overheating of the coil overtime and finally the insulation gave up after 8 years of service? This is F type insulation. The replacement motor...
  6. koshyeng

    Motor Stator failure

    Waross, This is 600 hp 480V VFD motor with average load of 520 amps. The controller is in the MCC which is roughly 150 ft from the motor leads. Enclosure is maintained at 78 F and there are alarms and safety shutdown interlocks if the enclosure temperature reached 95 F. No alarms nor the...
  7. koshyeng

    Motor Stator failure

    I couldn't upload files at this time as it shows run time error. I will try again after few hrs.
  8. koshyeng

    Motor Stator failure

    A 700 Hp motor failed during running with smoke and burnt smell very apparent. Upon inspection, found the stator windings burnt in the slots going to ground. I am attaching couple of pictures here to help indentify possible cause of failure. This motor was in service for 8 years and the previous...
  9. koshyeng

    Brainstorming Options for best mode of feeding Solids into a Batch Reactor

    I will go with option 3 too. Based on the solubility of the solids in water, you can make a thicker solution in a smaller vessel and pressure transfer to the reactor. Assuming you can have the mixing vessel above the reactor floor.
  10. koshyeng

    Pin Hole leaks on jacketed pessure vessel

    Ed a& Metengr, Thanks. 4 years ago, the chilled water is switched from regular industrial water (clarified water with pH 8 to 9) that was treated with nitrite type chemical to Demineralized water (pH 7.0) treated with Molybdate ( >100 ppm with water pH at 8 to 9). Last week we inspected...
  11. koshyeng

    Pin Hole leaks on jacketed pessure vessel

    One reason for me to suspect thermal stresses is I have noticed bulged jacket wall at 5 locations. This bulging is not all around the circumference of the jacket but only in few location. These points are inline with where the baffle is inside the jacket. It is hard to see the bulges with...
  12. koshyeng

    Pin Hole leaks on jacketed pessure vessel

    Chilled water is 50 F and hot water is 140 F. We use hot water for one hour during charging. At the end of polymer chanrging in to this vessel, we will start agitation and switch to chilled water.
  13. koshyeng

    Pin Hole leaks on jacketed pessure vessel

    metengr, I have attached some studies done on the cracked plate along with the pictures. It seems more like a thermal fatigue at the welds. There is 90 degree temperature swing at least 3 times/day. Appreciate your thoughts...
  14. koshyeng

    ASME Section 8 Div 1

    I need to fabricate a 25" long vessel with 14" Sch 10 pipe to use it a pilot plant for 2 - 4 months. Maximum operating pressure is 10psig. A elliptical head is welded to one end of the pipe and a flanged connection at the other end. IS this an ASME vessel or cane exempt from Section 8 Div 1...
  15. koshyeng

    Pin Hole leaks on jacketed pessure vessel

    Metengr, Thanks for your response. There is no crevice between the baffle and jacket wall. The last picture of the plate is upside down. The baffle is stitch welded to the jacket wall on the top side (3" weld). The 1/4" baffle is around the read area. Right above the baffle you see a ridge...
  16. koshyeng

    Pin Hole leaks on jacketed pessure vessel

    Any ideas on corrosion mechanism for the issue addressed above? thanks
  17. koshyeng

    Pin Hole leaks on jacketed pessure vessel

    Please see the attached description about the cracks and pictures. From the pictures, I ruled out crevice corrosion. Appreciate your help. http://files.engineering.com/getfile.aspx?folder=02bd204d-d8c4-4e3c-aa37-35e8f1a967b7&file=Leaks.docx
  18. koshyeng

    Pin Hole leaks on jacketed pessure vessel

    Ed, I agree with you that there could be tight fit in certain areas that could contribute for crevice corrosion. I did not see any corrosion signs on the baffles. See attached picture showing the baffle...
  19. koshyeng

    Pin Hole leaks on jacketed pessure vessel

    Ed, The crack is on jacket wall. The baffles are stitch welded to the shell wall and there is about 1/8" gap between the baffle circumference and jacket i.d . This vessel has been in service for 25 years and has never been taken out of service except for shutdowns. I assumed under deposit...
  20. koshyeng

    Pin Hole leaks on jacketed pessure vessel

    All, We notice pin hole leak as shown in the attachment. This is a jacketed pressure vessel with 304 shell and 517 CS jacket with internal baffles for chilled water. Could you please shed some light on damage cause? Chilled water is DI water at 47 F which is treated with molybdate. pH of...

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