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Recent content by boilerone

  1. boilerone

    Shell and Head Replacement - Design Calculations?

    If the original design and applicable code year are not changed then no new calculation is required. This is called 'repair' or 'replacement in-kind'.
  2. boilerone

    Fillet weld size for a thinner nozzle. Manufacturing problems?

    Farid44, Assuming your header is for ASME Sec I boiler application, my answers are: 1) Yes, 9mm fillet weld is practical. 2) Per Sec I PW-15.1.6, weld strength calc is not required if your design conforms with certain figures in Fig. PW-16.1. From your description your design matches type (z)...
  3. boilerone

    1949 Code Allowables

    Thanks, Jte. Just want to add that the current safety factor is 3.5 but not every state of the US nor every other country is accepting it.
  4. boilerone

    water tube boiler reduced pressure / derating

    I worked for boiler OEM companies for many years. The typical D-style boilers cannot run safely and continuously at 10% design capacities but might be possible at some higher loads. There are many possible problems for low-load operations. Not being able to maintain stable combustion, like some...
  5. boilerone

    big problem in the boiler tubes..please help.

    1. Corrosion - explains the rusts on the outer surface - bad fuel used, avoid. Might also cause creep happening at much lower temperature. 2. Tube material - explains the material appearing brittle. 13Cr-Mo44 looks correct but check, a. actual material used? b. heat treatment? 3. Frequent...
  6. boilerone

    gen bank erosion failures bi drum boiler

    If failures only happened on a few unique tubes then it could be vortex. The fix is to eliminate irregular tube spacings or arrangements which create gas path channels and allow flue gas to take shortcuts and hit certain tubes at much higher velocities. If damages including thinnings happened...
  7. boilerone

    Tips on buying pressure vessels from Asia

    I agree with Trottiey, except for very critical items like tubes and pipes for supercritical and ultra-supercritical plants, the majority of the rest of items are all made from Chinese materials and by Chinese manufacturers, especially the pressure vessels such as 100% of the steam drums and...
  8. boilerone

    Frequent Start-up/Shutdown effects on Fertilizer Plant

    Like Metengr said, failure from fatigue is the major concern. One famous term is the 'S/N curve'. Fatigue should include mechanical, thermal and, particular to your chemical industry, corrosion fatigue. Here are some quick Wikipedia links: http://en.wikipedia.org/wiki/Fatigue_(material)...
  9. boilerone

    Third World Countries

    Notice that first, English and Chinese versions of Wiki have different maps and second, even though neither map shows China to be still a 3rd word country, the leadership still claims 'we always belong to the Third Word' and further more, in the news, 'U.S. Downgraded to Third World Nation'...
  10. boilerone

    Triangular plate stress calc.

    Like Bernoullies123 says, the Roark's book already contains a lot of straight formulas for many special situations.
  11. boilerone

    Boiler Design: Top or Bottom Supported?

    RR79, This might make it easier to understand why change from bottom-supported to top-supported as boilers get larger: If you imagine making small and large boxes from the same thin wall material, such as paper, and leave them on the ground. Below certain size the box cans still be...
  12. boilerone

    Sulphur content of fuel oil and superheater fouling

    Athomas236, You contractor is right. High-sulfur fuel oil DOES have big problem of generating sticky ash to the heating surfaces, especially on the superheater elements and thus reduces heat absorption and the steam production of boiler. The other and bigger concern is, like most others...
  13. boilerone

    Tips on buying pressure vessels from Asia

    I helped my company to buy pressure parts from China in the past. Just need to find the ones with good reputations, not the cheap suppliers plus hire good inspectors/agents. After a few rounds, you will get to know the culture and the tricks and be successful. If you feel intimidated about...
  14. boilerone

    Bolt Specification for Diverter Damper

    Make no mistake, MJCronin, according to the question asked this bolt is for the boiler flue gas damper which is a non-pressure part for which application B7 can be used for much higher temperatures plus B7 matches the typical low-alloy damper blade and frame materials used for the 480 deg. C...
  15. boilerone

    Tie bar welded in staggered arrangement to boiler tubes

    It is not the tubes that need welding but the tie bars need to count on the welds to each tube to carry the horizontal loads plus this design has the concern of possible tearing the tubes open through the tiny bits of welds if have localized and concentrated loads. It is also easy to burn holes...
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