Control valve specifications and selection requirements

Field Instrumentation Valves
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valve%20parts

Control valves are the most widely used control element in every kind of process industry. Control valve selected for an application should be the perfect combination of specifications including valve body, material, trim construction, temperature & pressure rating.

Capacity specifications and operating pressure levels of the unit must also be taken into account when choosing a control valve to ensure adequate operation without unnecessary initial expense.

To select a control valve for a particular purpose one needs technical person assistance or you should have good knowledge in valve specification. Here in this topic, we are trying to help to understand the basic of valve selection and specification.

Selection criteria for control valves:

  • Type of fluid to be controlled: What fluid will you be controlling? Water? natural gas?

  • Temperature of fluid:

  • Viscosity of fluid

  • Specific gravity of the fluid

  • Flow capacity of the control valve

  • Inlet pressure at valve: State maximum and minimum inlet pressures expected to be handled by the control valve.

  • Outlet pressure at valve: The control valve is expected to handle maximum and minimum outlet pressures.

  • Pressure drop during normal flowing conditions

  • Pressure drop at shut off

  • Noise level

  • Degrees of superheat or existence of flashing if known

  • Inlet and outlet pipeline size and schedule

  • State whether any special tagging information is required for the control valve

  • Body material of the control valve

  • End connections and valve ratings

  • Valve action desired when instrument air fails

  • Instrument Air Availability

  • Valve type number

  • Valve size

  • Valve body construction

  • State the desired valve trim materials required

  • Actuator size

  • Bonnet Style

  • Valve packing materials

  • Valve accessories

Material Selection for valve:

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Specification for different control valves:

Standards for Shut off valve:

  • DIN 3381 Safety Devices for Gas Supply Installation with operating Pressure up to 100 bar

  • API 6D “Specification for Steel Gate, Plug and Ball valves for Pipeline Service” (latest edition).

  • ASME B 31.8 “Gas transmission and Distribution Piping systems“ (latest Edition)

  • ANSI B 16.5 Steel Pipe Flanges, Flanged Valves and Fittings (last edition)

Standards for Safety Shut off Valves:

  • API 6D “Specification for Steel Gate, Plug and Ball Valves for Pipeline service” (latest edition).

  • API RP 521 Guide for Pressure-Relieving and Depressurizing Systems

  • ASME B 31.8 “Gas transmission and Distribution Piping Systems“ (latest Edition)

  • ASME Boiler and Pressure Vessel code, Section VIII

  • ANSI B 16.5 Steel Pipe Flanges, Flanged Valves and Fittings (last edition)

  • DIN 3381 Safety Devices for Gas Supply Installation with operating Pressure up to 100 bar.

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