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  1. Steve010

    Pressure transmitter with flange rating below process design P/T

    No,Duplex SST is accepted, but isn't it cheaper to use 316 SS flange rating 900# than a Duplex 316 SST flange rating 600# ?
  2. Steve010

    Control Valve Minimum Pressure Rating

    The trim is 316 ss so it will resist corrosion, but the body is cs like the pipe. Trim does not require corrosion allowance but valve body may require. Loosing thickness from the body by time will derate the valve. What is your opinion?
  3. Steve010

    Control Valve Minimum Pressure Rating

    Vendors do not include corrosion allowances in their manufacturing process. They manufacture valves with fixed thicknesses. Due to their standard machining processes, what i know is that they will never add more thickness. I asked masoneilan and they confirmed that valve thickness is standard...
  4. Steve010

    Control Valve Minimum Pressure Rating

    After the corrosion allowance and according to the piping spec. the 1" pipe schedule is sch.160 which means that the pipe wall thickness is 6.35 mm. According to ASME B16.34 the minimum body wall thickness for 1" valve with rating 150# is 3.9 mm. This means that the pipe wall thickness is...
  5. Steve010

    Control Valve Minimum Pressure Rating

    Yes, the trim is corrosion resistant 316 SS, but the body is carbon steel, so it will loose thickness by time, just like the pipes. Piping include corrosion allowance of 2 mm for the pipes, how is that taken into account for the valve? especially that small valves with rating 150# has a very...
  6. Steve010

    Control Valve Minimum Pressure Rating

    Something came across my mind. The valve body thickness does not take into account corrosion allowance. for example when piping specifies a corrosion allowance of 2 mm for the pipes this corrosion allowance is not taken into account by the valve manufacturer. For Small valve sizes, the body...
  7. Steve010

    Control Valve Minimum Pressure Rating

    Also the piping project spec states that globe valves for sizes from 2" to 4" flanged RF with rating 150# for that class. And that globe valves from 1/2" to 2" are socket weld rating 800#. Does that makes the 1" control valve with flanged RF end connections rating 150#, deviate from the piping...
  8. Steve010

    Control Valve Minimum Pressure Rating

    Biginch. Thank you very much that's a very good point that never crossed my mind. Yes frequency of vibrations depends on dimensions. I know how to calculate the cooling effect from depress. Using the jt effect. But how can i decide whether vibrations are going to happen or not ?
  9. Steve010

    Control Valve Minimum Pressure Rating

    I am not a mechanical engineer. But isn't vibration an issue that is solved by good pipe supporting and not by size and increasing rating? Isn't rating only a measure of the pressure/ temperature the valve and pipes can withstand?
  10. Steve010

    Control Valve Minimum Pressure Rating

    Why did API Recommended Practice 553 (Refinery Control Valves) state that valves for vapor depressurizing should be minimum 2" rating 300# for mechanical integrity? isn't the rating determined solely by the design pressure and temperature ? What is the relation between size and rating and such...
  11. Steve010

    Control Valves' Pressure Rating

    Why did API Recommended Practice 553 (Refinery Control Valves) state that valves for vapor depressurizing should be minimum 2" rating 300# for mechanical integrity? isn't the rating determined solely by the design pressure and temperature ? What is the relation between size and rating and such...
  12. Steve010

    Control Valve Minimum Pressure Rating

    You mean it is ok to use a 1" valve with flange and body rating 150#?
  13. Steve010

    Control Valve Minimum Pressure Rating

    No, it is not domestic water system. It is an oil and gas plant (fuel gas blanketing service). The piping is 1". Should i use a 2" valve on a 1" pipe? I have seen that most companies standards alow the use of control valves' with sizes not smaller than 1".
  14. Steve010

    Control Valve Minimum Pressure Rating

    Sorry, I was thinking to ask the piping/mechanical engineers as well. what do you mean by practicality ? I found that most vendors manufacture them (so it seams that nothing inhibits their use). I am concerned if there may be any mechanical concern on control valves (globe valves) with small...
  15. Steve010

    Control Valve Minimum Pressure Rating

    Apart from companies'/owners' standards, is their any technical reason (valve cracking, mechanical integrity ..... etc.) or any obligatory code or standard that prohibits the use of control valve rating 150# for raised face flanged control valves (Globe Style) smaller than 2 inches in oil and...
  16. Steve010

    Pressure transmitter with flange rating below process design P/T

    I agree with you. Another question. Does'nt the code (ASME B16.5) has a safety factor? if it has, what is it ? For example if i have a case that my P/T is just above the design conditions by 0.5 psi, should i be comfortable about it?
  17. Steve010

    Pressure transmitter with flange rating below process design P/T

    There is no relief pressure, this is on the outlet of oil wells. The 1250 psig and the 175 F are the design conditions.
  18. Steve010

    Pressure transmitter with diaphragm seal for very high salinity application

    The body is wetted, however in figure c it is non-wetted because of the special design of extending the diaphragm over the flange raised face which covers the body.
  19. Steve010

    Pressure transmitter with flange rating below process design P/T

    I am purchasing a 600# 2 inch flanged pressure transmitter. The piping is 600# carbon steel. There is a process condition that could last for days with a pressure of 1250 psig and a temperature of 200 F. According to the ASME tables, a 600# carbon steel flange maximum pressure is 1350 psi at...
  20. Steve010

    Pressure transmitter with flange rating below process design P/T

    I am purchasing a 600# 2 inch flanged pressure transmitter. The piping is 600# carbon steel. There is a process condition that could last for days with a pressure of 1250 psig and a temperature of 200 F. According to the ASME tables, a 600# carbon steel flange maximum pressure is 1350 psi at...

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