Control Valve Commissioning

By Dovydas Kersys · Chapter 41 of 58 in Machine Commissioning.

Before you begin: Follow the machine documentation, risk assessment, site procedures and lockout/tagout requirements. Commissioning can expose personnel to electrical energy, stored pressure and unexpected motion. Never defeat a safety function merely to make a test easier. Examples and diagrams are generic and must be checked against the actual machine.

Control valves need electrical/pneumatic signal checks, travel verification, fail position, position feedback and interaction with the process. Mechanical linkage and air quality can be as important as PLC scaling.

Why this matters during commissioning

A valve that reaches 50% command does not necessarily produce 50% process effect. Commissioning should first prove travel, then process response.

Commissioning procedure

Verify valve/positioner supply and signal type.
Command several positions across the range.
Observe actual stem/shaft travel and position feedback.
Check fail-open/fail-closed action by removing command or air as appropriate.
Verify travel stops and no mechanical binding.
Record deadband/hysteresis if significant.

Common failure patterns

Positioner calibrated opposite to PLC output direction.
Valve linkage slips.
Air pressure insufficient at high process load.
Fail action different from process safety requirement.

Evidence to record

Measured value and test point
Expected value / expected state
Observed value / observed state
Pass/fail result and any deviation
Name/date or responsible person where required

FIELD RULE: Prove physical valve travel before tuning the process around it.

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