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  1. UKCats

    Benzene Material Selection/Corrosion Rates

    Looking at using benzene as a solvent up to 300F. It appears carbon steel has less than 2 mpy under 100F (storage) and 316SS up to 150F at higher concentrations. However, benzene will vary in our seperation column (0-100%) and I have found Alloy 20 to be acceptable to 212F in several...
  2. UKCats

    45-degree cut on Open Pipe

    Does anybody have a scientific reference (or test data) to why the end of an open pipe is often cut at a 45 degree angle. My recollection is a straight cut could build up harmomics (standing waves) and reduce capacity. If you notice, organ pipes, and many automobile exhaust pipes are cut at an...
  3. UKCats

    45 degree cut on PSV Discharge Piping

    Does anybody have a scientific reference (or test data) to why end of an open pipe is cut at a 45 degree angle. My recollection is a straight cut could build up harmomics (standing waves) and reduce capacity. If you notice, organ pipes, and many automobile exhaust pipes are cut at an angle...
  4. UKCats

    U-2(g) - Stiffining for Internal Pressure

    Can I use structural stiffing members in Pressure Vessel design to restain internal pressure??? I think not. UG-27 and UG-32 provide formulas to detmine shell and head thickness for internal pressure. I am working with a Fabricator that claims you can use stiffing members with an FEA for...
  5. UKCats

    "RT" Namplate Stamping

    I have a 1968 "U" stamped pressure vessel not registered with the National Board. I do not have a U1 form. The vessel's nameplate has the shell and head thickness stamped on it and using these as-fabricated values, it doesn't pass the code using joint eff of 0.85. The Code Nameplate merely...
  6. UKCats

    GMAW

    I have seen specs that do not allow Gas Metal Arc Welding. What are the negatives with this process???
  7. UKCats

    Enlarging Bolt Holes - Routine or R-1

    I have a heat exchanger bonnet that has twenty-four (24) 3/4-inch holes in its flange. I need to enlarge the bolt holes to 7/8-inch to match a new shell. I have run the calc, and the code supports the larger holes. Would enlarging the holes be considered an Alteration???
  8. UKCats

    WPS for P8-1 Material

    I recently ordered a custom made 316L SS vessel. The WPS they sent me for approval is for 304L SS base material. Since both 304L and 316L materials are a P8 Group 1 materials, I think this WPS is okay??? Anybody know???
  9. UKCats

    "S", "A", and "H" Boiler Stamps

    What's the difference in an S, A, and H stamp on boilers???
  10. UKCats

    100% Iodine...Ouch ! ! !

    I have a jacketed Inconel 625 vessel that we use to melt iodine pellets at 120F and 50 psig. The vessel wall has corroided from 1.25" to 1/2" in 10 years...ouch (75 mils/yr). We did an overlay 2 yrs ago and lost 0.300-inches. We do not want to replace the vessel for 2 more years so...
  11. UKCats

    Stress Relieving 304/316 SS

    After welding, is there any reason why you would stress relieve... 304/316 SS 304L/316L SS 400 series SS Other Stainless steels??? Aren't the benefits minimal???
  12. UKCats

    ASME Section VIII - Cyclic Loads

    How does ASME Section VIII handle cyclic loads. Does it use lower allowable stresses??? or in other words, apply a penalty. I have a vessel that is steam sparged and it shakes. It has failed..cracked. To replace it, I want to apply a lower allowable stress based on fatigue which would lead...
  13. UKCats

    Alloy 825

    Where can I get some S-N data (allowable stress vs. number of cycles) for Alloy 825 material??? I have a fatigue failure and need to recommend replacment options.
  14. UKCats

    SA-283, Grade C

    I have an older tank made of SA-283, Grade C (T.S. 55 ksi)that I want to do a path repair on the bottom using SA-516. Will I have a brittle issue if I perform a repair with SA-516-70. My thoughts are I should be closer to 55ksi and use SA-516-60...or is 15 ksi disparity between carbon steels...
  15. UKCats

    Fatigue Failure of Alloy 800

    I have an agitated vessel that we inject live steam into for direct heating/mixing. The vessel is 8 y/o. The welds at the support lugs have developed leaks due to cracks. The shell is Incoloy 800 and the support lugs, which distribute the stresses, are SA-285 carbon steel. I'm looking to...
  16. UKCats

    Vacuum Rating of Atmospheric Storage Tanks

    I have an atmospheric storage (actually 20 in w.c.) tank with a flat bottom, 2:12 cone roof. It's not built to API 650 but looks a lot like one. I was wondering how high of vacuum rating it could take. API 650 specifically says limit the tank to 1-inch w.c. external pressure. FM Loss...
  17. UKCats

    Flanged/Flued vs. Bellows Expansion Joint

    I have recently been informed that the most recent (2002) ASME Section VIII, Div. 1 Code moved Appendix C-C (Flanged/Flued Expansion Joints) to a Mandatory Appendix (Appendix 5 I think???). The impact of this is a majority of heat exchangers being fabricated today have Bellows Type Expansion...
  18. UKCats

    Carbon Contaimination of Stainless Steel

    During the fabrication of stainless steel pressure vessels, it is very customary to specify not to use grinding wheels or wire brushes that have been around carbon steel material. I have seen first hand the minute corrosion that can occur when this is not adhered to. Question.... Can the...
  19. UKCats

    Nitrogen in Steel

    I notice in many of the duplex steels, and alloy steels, higher concentrations of nitrogen are used (say 0.2-0.3%). As a Chemical Engineer, I can't comprehend how gasious nitrogen can stay in solution of steel at 2000F. Boiler Feedwater is stripped essentially all of its O2 and N2 (50 ppm) at...
  20. UKCats

    Galvanizing Studs

    Does hot dip galvanizing a stud/bolt lower its yield or tensle strength? I understand Cadmium plated studs can fail due to liquid embrittlement above say 450F. Are their similar drawbacks to galvanizing??? If so, at what temperatures???

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