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  1. Bonswa

    Circumferential weld on tank annular plate

    How far is the projection? is it close?
  2. Bonswa

    Corrosion Pitting

    How deep is this pitting? What's the nominal plate thickness? Approximately how much of the shell has this pitting? If you're still above T-min, you should look into mitigation by coating the shell. A lot of our gasoline tanks have that GENERAL pitting throughout the entire shell and floor...
  3. Bonswa

    Pontoon Leaks

    foam is great, but the problem with foam is the removal of it when you're ready to make a permanent repair. what i've switched to is the "McDonalds balls". they're the plastic hollow balls that you fill the pontoon with to displace the product with air. They're a quick, cheap solution that is...
  4. Bonswa

    Hot Work above Floating Roofs

    What is the height of the tank? What is the height of the leak? What is the product being stored? What is the thickness of the shell that would be welded on? In my opinion, if you absolutely cant limit the height of the tank to the height of the leak, then you could repair it. you could try a...
  5. Bonswa

    Flatness

    if you're talking about plumbness, normally we use a plumb-bob. Just drip a line over the edge of the roof and measure the distance from the shell to the line at a preferred interval. usually we measure the top, middle, and bottom of each course. if we cant use a manlift in the area, the we've...
  6. Bonswa

    API 653 "Chime" Projection outside of bottom weld

    Here's my thought process on this one: -When you can visually see heavy corrosion on the bottom side of a chime, you would normally gather a good bit of U.T. data in that area as well as the rest of the chime. -The minimum thickness on a tank with no leak detection or liner is 0.100" -The...
  7. Bonswa

    Open Top Storage Tank

    My first thought is the same as IFR's second option. Look at it from a purely structural point of view. build parallel rafters and set the grid on top as if it were any other grated structure. I would build it to where it doesnt touch the tank at all. Put 4 columns up on the outside of the tank...
  8. Bonswa

    checklist

    You should invest in the 11th edition of API 650. It's the current standard for new construction of storage tanks. also, i dont remember EVER seeing a new construction checklist in any edition of 650. I had to create my own checklist. I would recommend you follow API-650, 11th edition...
  9. Bonswa

    Bottom tombstone repairs clost to shell butt welds

    IFRs - I did mean "V" in 9-1. The reason I would go with that is because that distance is acceptable when putting a lap patch on the shell that crosses a vertical weld seam. For all lap patches on the shell that cross a vertical weld seam, the distance of the new weld from the existing seam...
  10. Bonswa

    Bottom tombstone repairs clost to shell butt welds

    I would use figure 9.1 in 653. No, it doesn't clearly state the distance from a vertical weld seam when dealing with a tombstone, however you should use the same spacing as a lap patch. In figure 9.1, use "V" for that distance. The reason i say this is because the tombstone is going to be the...
  11. Bonswa

    API 650 Service Test

    I agree with MJCronin. The contractor does not have the right to wave a hydrotest.
  12. Bonswa

    Thickness Measurement in Aboveground Storage Tanks Bottom Plates

    If you know whether or not the tank has an annular ring, this could be very easy. If the tank has no annular ring, then just take UT readings on the chime. If the tank has an annular ring, and you REALLY need the readings, you can excavate the area to where you can take a UT reading about 2-3...
  13. Bonswa

    Thief Hatch Installation

    API-650 sends you to ASME B16.5 for all flange specifications. Check out ASME B16.5. Flange dimensions start on page 64. You'll find all the information you can possibly need there. Hope this helps.
  14. Bonswa

    Most economical Height/Diameter ratio - Field Fabbed Tanks

    IFR's right... not to mention that a 40ft high tank with 10ft courses, there's less welding involved than a tank with 8ft courses. In turn, that means less NDE. Either way is acceptable. Are you saying with the H/D ratio that a 40ft high tank should be between 40ft and 48ft diameter?
  15. Bonswa

    API 650 Upper plate thicker than lower plate

    I would think that as long as you have the 4:1 taper it would be acceptable. Now that i think of it, that tank i mentioned even has a thickened insert plate that's either 1.25" or 1.5". I know they have a massive taper on it too.
  16. Bonswa

    API 650 Upper plate thicker than lower plate

    I cant seem to find anything on it either. I would think that it would be too much of an offset. Just for reference, The 300ft diameter tanks that i've worked on have shell courses like this: 1st course - 1.105" 2nd course - 0.850" 3rd course - 0.637" 4th course - 0.433" 5th course - 0.375"...
  17. Bonswa

    API 650 Upper plate thicker than lower plate

    The only situation i can think of would be a thickened insert plate on the upper course. It's not very common considering your main nozzles are usually on the first course, but it is possible. Check out figure 5-7B. there's a small detail about thickened insert plates requiring the 4:1 taper...
  18. Bonswa

    LFO Tank Nozzle Inlet Location

    I dont see any reason why you wouldnt place it near the bottom of the tank, as with most standard tank designs. Check out API-650, Section 5.7 for all of your design criteria and requirements. Hope this helps.
  19. Bonswa

    Tank floor inspection

    API-653 Appendix B has EVERYTHING you need to know about the flatness of a tank bottom. It has everything from edge settlement to localized bulges away from the shell. All acceptance criteria and calculations are given as well. Hope this is what you're looking for.
  20. Bonswa

    UT in lieu of RT question

    Although costly, I think Phased Array would be your closest option to RT. It's still looked at like UT, but can produce the results that you would expect from RT.

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