Passing Control Valves Cause Yearly Losses in Production Plant

Instrumentation engineering root cause analysis (RCA) of control valves passing and they cause yearly 10 million rupees losses in a production plant.

Article Type:Root Cause Analysis (RCA)
Equipment Type:Control Valves
Author:S. Raghava Chari

Note: This root cause analysis (RCA) is from real-time scenarios that happened in industries during the tenure of two or three decades ago. These articles will help you to improve your troubleshooting skills and knowledge.

Passing Control Valves Cause Yearly Losses

The author during his review for improvements after the hectic commissioning problems was over the Table 1 listed 0.5% leak class double seat normally closed vents.

He estimated the control valves (CVs’) leaks cost as Rs 20 million yearly (80s figures).

Tag #Normally closed RFG-Reformed Gas Vents
PCV 125RFG Waste heat boiler
PCV 126RFG CO2 absorber
PCV 127RFG Methanator
PCV 217Urea Plant Vapor NH3  Liq NH3 storage tank
Table 1 Leaky Vent Control Valve Details
Passing Control Valves Cause Yearly Losses

Author Solution

At his request, the vendor quoted 0.1% leak class balanced plug control valve body assemblies that would accept the existing actuators and valve body assembly + actuator for PCV 125.

The cost was hardly $ 2000; the stopped leak savings would pay that in few days. Yet the management stubbornly disapproved.

Finally, he won approval by:

  1. His yearlong relentless persuasive efforts
  2. Demonstrating testbench rotameter measured 1.5% leaks
  3. Impressing the actual leak would be more because of the differential thermal expansion of the carbon steel bodies and SS 316 trim


The technical services department confirmed an estimated Rs 100 million saved leak losses after fitting the new valve bodies + old/new actuator assemblies.

Author: S. Raghava Chari

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