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  • Users: MadDog88
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  1. MadDog88

    Heating 1.25Cr-0.5Mo to 900 deg C for 6.6 hours

    Hello all, I am getting a refractory lined vessel fabricated for hydrogen service (reformed gas outlet header) and I am concerned that the refractory dry-out temperature and duration will cause material degradation to the 1.25Cr-0.5Mo shell (1100mm OD, 20mm thick). The dry-out schedule states...
  2. MadDog88

    Pressure rating of flexible hose??

    Hello all, In our refrigeration area of our ammonia plant, we have numerous double block and bleeds for isolations. As these isolations are carried out infrequently there is no hard piping on the bleed/drain line to vent. So, once the two block valves are closed, a flexible hose is connected...
  3. MadDog88

    Electric motor base/platform

    Are there any standards or requirements that dictate how a steel motor base/platform should be designed? ie. Should it be completely rigid or is some flexibility required for start-up torque? Are there mass requirements? etc. I want to modify a steel structure designed for a 2.2MW motor so a...
  4. MadDog88

    ASTM A672 Gr C70 Cl 22

    Hi, Can somebody please tell me the chemical composition for ASTM A672 Gr C70 Cl 22? I cannot find it in any of the specs. Is it similar to ASTM A106 Gr C? Thanks a lot for your help. Mad Dog
  5. MadDog88

    Low Temperature Service???

    I am wondering what is the definition of "Low Temperature Service". For example, what is the max temperature that a ASTM A420 Grade WPL6 elbow can be used? How do the chemistry and mechanical properties differ from non-low temp service? Thanks in advance
  6. MadDog88

    SCC of ammonia storage tanks

    I have read that between 100ppm and 1000ppm of water should be added to liquid ammonia being stored in carbon steel tanks (-33 deg C and ambient pressure). How does the water addition eliminate the risk of SCC? Also, can SCC occur if there is no oxygen present? Thanks in advance for your...
  7. MadDog88

    Effect of drilling though compensating pad??

    We have a refractory lined cylindrical pressure vessel which is exhibiting some hot spots due to gas tracking through fine cracks. The vessel ID is too small to repair from the inside so I wanted to weld some 1/4"- 1/2" nozzles onto the vessel and inject liquid refractory from the...
  8. MadDog88

    Welding carbon steel at high temps???

    We have a refractory lined, carbon steel collection header which has sustained localised refractory damage and subsequent hot spots. We are unable to shut the process down to repair the refractory so I want to investigate an on-line “temporary” repair. I am proposing to weld nozzles onto the...
  9. MadDog88

    Welding C/S at high temperatures????

    We have a refractory lined, carbon steel collection header which has sustained localised refractory damage and subsequent hot spots. We are unable to shut the process down to repair the refractory so I want to investigate an on-line “temporary” repair. I am proposing to weld nozzles onto the...
  10. MadDog88

    L-14 Iron???

    We have a pump casing made from L-14 iron and we want to know if we can carry out some minor weld repairs. After some searching, I have not been able to find a material chemistry. Does anybody know of this material and can it be successfully welded. Thanks
  11. MadDog88

    Ductile-Brittle transition temperature

    Hello, I want to carry out a pipe freeze with liquid nitrogen on a 350mm carbon steel pipe (containing cooling water) to replace a passing isolation valve. I think that it should be OK but I want to check the ductile-brittle transition temp of ASTM A53 grade B pipe but I cannot find it...
  12. MadDog88

    BS3603 - 410 and BS1501 - 430??

    Hello, Can somebody please tell me the equivalent or the chemical composition of the following materials. BS 3603 - 410 BS 1501 - 430 Are these equivalent to AISI 410 and 430 or something different. Thanks in advance.
  13. MadDog88

    Hastelloy grade selection??

    We are looking at using Hastelloy bolts for service in our concentrated HCl facilty (33%). Which type of Hastelloy is best for corrosion resistance at ambient temperature up to 50 degrees Celcius?
  14. MadDog88

    Wear material for slurry pipe

    We currently use a carbon steel reducer on the discharge of a 3-2 Warman slurry pump (slurry is iron based, approx 90 deg C). The carbon steel discharge spool wears regularly and I was thinking about replacing it with a stainless steel spool, possibly 304 or 321. Will this give me better wear...
  15. MadDog88

    Difference between nm3/h and sm3/h??????

    Hello, Can somebody please tell me the difference between nm3/h and sm3/h and how to convert between the two? Thanks in advance for your help.
  16. MadDog88

    Thermal Expansion - Steel Vs Fibreglass

    Can somebody please give me some general figures on the difference in thermal expansion coefficients between steel and fibreglass. I would have thought steel had a higher coefficient but I have been told otherwise and can’t find any solid data myself. Thanks in advance.
  17. MadDog88

    Recip Compressors

    We have a reciprocating compressor which compresses inert gas (mainly N2) from 0.5 bar to 19.5 bar over 3 stages (4 cylinders). Can we use the same compressor to compress CO2 to the same pressures? This subject is quite new to me and I was wondering if the larger atomic weight of the CO2 would...
  18. MadDog88

    Over greasing

    Can somebody please tell me how overgreasing of bearings can lead to incresed bearing temperatures? Thanks in advance.
  19. MadDog88

    Membrane Stress

    I realize that this is a simple question for this forum but could somebody please explain the term 'membrane stress' for me. I am looking through some old vessel design calculations and, being quite new to this area, I am having trouble understanding a few of the terms. Also, if anyone has a...
  20. MadDog88

    Cast iron phase transformation

    We have a cast iron fan hub which is stuck/corroded onto a alloy steel shaft. I would like to apply heat to the hub in order remove it from the shaft. I am aware of the the effect of heat on Q+T alloy steel but how will heat from an oxy torch affect the microstructure and physical properties of...

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