Specifying of applying an industrial control valve? Here is a comprehensive checklist to help:
PROCESS CONSIDERATIONS:
- What is the medium to be controlled. Is it a liquid, gas, or slurry?
- Is it corrosive, abrasive, explosive or clean single-phase medium?
- What is the upstream or inlet pressure. Don’t guess – use a gauge.
- What is the downstream pressure when valve is closed, and when flowing?
- Are the Vapor pressure, viscosity or specific gravity and critical properties known?
- What are the inlet and outlet pipe size(s) [ May be different ] and schedule?
- Normal, Minimal, and Startup conditions for flow, pressures and temperatures?
- What impact will even a small seat leakage create when shut off?
- What Class is required?
- Is the installation in an occupied area. Noise or other hazardous considerations?
- What is the “fail safe” orientation? In place, closed or open?
- If in a fail safe orientation, is a manual readjustment to be expected?
- What is the ANSI Pressure Class of the pipe flanges and valves in the loop?
- What has been the operational history in an existing application?
- What material is the existing piping made of. Is it considered compatible?
- Is there an existing valve in place and a face-to-face dimension to match?
- Where will the valve be located – elevation – within a piping nightmare?
- What maintenance – routine or preventative is normal and expected?
- What are preferences for Control Valve Actuation – pneumatic or electric? WHY?
- Is the customer going to actuate it himself and buy a “bare stem” valve?
- Is the stem boss compatible with his actuator stem. Double “D” or square?
- Is the calculated flow velocity below limits of 100 – 125 fps for saturated steam?
- Is the calculated flow velocity below limits of 5 fps for liquids?
- Is the calculated flow velocity below limits of 250 – 400 fps for gases?
“REAL WORLD” APPLICATIONS CONSIDERATIONS:
- Could moving vehicles damage the valve, in a specific installed location.
- Might seismic forces or fires present a danger to workers.
- What codes may be in effect? Body pressure Code, Leakage Criteria
- Might workers use the valve as a stepladder when conditions dictate?
- Is the application a “continuously modulating” or an on / off practice?
- Might the process be shutdown for nights or weekends?
- What might result when started back up after an extended shutdown?
- Use your imagination, anticipate the worst, and ask more questions – more, in this case, is always better.
- What range air set is available for actuator or positioner?
- Could it allow a higher than safe pressure?
- Where will the user store documentation for IO&M purposes?
- Is routine maintenance allowed or is an annual shutdown more typical?
- Could moving vehicles damage the valve, in a specific installed location?
- Might seismic forces or fires present a danger to workers?
- What codes may be in effect? Body pressure Code, Leakage Criteria?
- Might workers use the valve as a stepladder when conditions dictate?
- Is the application a “continuously modulating” or an on / off practice?
- Might the process be shutdown for nights or weekends?
- What might result when started back up after an extended shutdown?
- Use your imagination, anticipate the worst, and ask more questions – more, in this case, is always better.
- What range air set is available for actuator or positioner?
- Could it allow a higher than safe pressure?
- Where will the user store documentation for IO&M purposes?
- Is routine maintenance allowed or is an annual shutdown more typical?
PHYSICAL AND CONFIGURATION CONSIDERATIONS:
- Flowing media to be controlled. Steam, Liquid or Gas?
- Pressures upstream and downstream, therefore the differential.
- Two way – modulating, or on/off. Three way diverting or mixing?
- Is the material abrasive, explosive, or clean?
- Hot or Cold water chemically treated?
- What are inlet and outlet pipe sizes and schedules?
- Maximum, Normal and Startup conditions?
- Leakage allowed?
- Valve in occupied area?
- Previous usage history?
- Pipe material of construction?
- Actuation Pneumatic or Electric Maintenance allowed or anticipated?
- IO&M storage and accessibility?
- Control signal – PID compatibility?
- Mounting restrictions?
- How was valve “sized?”
Checklist courtesy of Warren Controls.
Please consult with an application expert before selecting or installing a control valve.
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