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wingman1985
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Join Date: Jul 2009
Location: China
Posts: 146

Control Valve Terms

08/07/2009 7:12 AM

Where practical "roll" or "drop-out" all control valves to prevent pitting of the valve seats due to deposition of debris on the seat.

what is the meaning of "roll" or "drop-out"?

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PWSlack
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#1

Re: "roll" or "drop-out"?

08/07/2009 7:24 AM

It might mean open them fully. It might mean close them fully. So it depends upon context. Some questions to help evaluate the way forward:

  • Has a formal HazOp Study been undertaken on this plant?
  • Is debris in the process stream an issue?
  • Could up-stream filtration or straining reduce or eliminate the size and levels of debris passing through control valves?
  • Is the pipe material-of-construction appropriate for the fluids being conveyed or has corrosion become significant?
  • Are pipe velocities so high that erosion, as opposed to corrosion, is the underlying problem?
  • Are the valve trim materials correct for the fluids being conveyed?
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wingman1985
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#2
In reply to #1

Re: "roll" or "drop-out"?

08/07/2009 9:26 PM

thanks for the assist, could u pls provide more info on this subject?

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