Find Out Why 6 Out of 7 Regulators
Failed PQI Testing

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Parts Quality Testing

In 2006, Exelon PowerLabs’ PQI predictive analytics program was founded to safeguard against downtime due to critical parts failure. Exelon PowerLabs uses historic model-specific failure data trends to identify which parts to test. PQI critical characteristics testing ensures defective parts are identified before installation, reducing downtime, labor and logistics costs, and yielding substantial warranty replacement savings.

The PQI program tests and identifies deficient parts prior to inventorying or installation.

Case Study: Seven Pressure Regulators Undergo PQI Testing

A customer sent seven pressure regulators to be tested against the known failure modes and added additional plant-mandated acceptance criteria to the standard PQI testing procedure. These regulators were to be installed in a valve that performs a highly critical function for the nuclear power plant.

The regulators were PQI tested for the following critical functionality: leakage, function, input/output, repeatability. All seven of the regulators passed the leakage and function tests.

PQI Pass or Fail Test Results

  • Leakage: 7 out of 7 Passed
  • Function: 7 out of 7 Passed
  • Input/Output: 3 out of 7 Failed
  • Repeatability: 3 out of 7 Failed
  • Additional Plant-Mandated Acceptance Criteria: 6 out of 7 Failed

Identifying the Failures

While proving functionality during normal plant conditions is important, maintaining transient functions during a disruption is critical. Exelon PowerLabs performed tests by disrupting the pressure to ensure repeatability. The output lock up test measured flow stabilization. Once the valve regulators closed, pressure should stabilize and remain at set pressure. Among the components tested, three regulators failed due to continuous pressure drift from original set pressure.

PQI Helped Prevent Unplanned Outage

Apart from the PQI standard testing procedures, an overshoot pressurization test was performed on the last qualifying parts that had not yet failed additional plant-mandated acceptance criteria. Since the regulators were to be installed in a critical application, it is crucial parts perform at the required pressurization.

A pulse test was then performed on the remaining four regulators. In this test, a large pulse of air is applied into the regulator input to ensure the pulse will not blow the rupture disc, as it can cause an unplanned plant transient. Of the four regulators tested, only one passed these plant-mandated tests. The PQI testing plus plant imposed tests confirmed only one of the seven regulators met plant specifications for the application. The three regulators that failed the over pressurization test can still be used in the plant since they passed the other PQI testing standards and qualified as functional parts. However, these three regulators cannot be used in the application originally intended.

PQI Savings Unfolded

Out of the seven regulators, six failed Exelon PowerLabs’ PQI testing as well as the additional customer-imposed testing requirements. PQI helped prevent unplanned plant transients that could have affected nuclear safety and plant reliability. The six regulators were returned to supplier and exchanged for new parts at no additional cost. Replacement parts were then PQI tested prior to plant receipt and successful installation.

Exelon PowerLabs’ Parts Quality Initiative is a dynamic predictive analytics program constantly adapting as new parts are tested, and new failure modes are identified. With hundreds of parts tested daily, Exelon PowerLabs continuously updates its OneLab PQI database and PQI tests plans so customers can zero in on problematic parts and easily avoid component failures. PQI continues to inform customers on how to better manage inventory to a higher level of quality.