Root Cause Analysis 1 min read

Analysis of causes of failure of a pneumatic valve: contamination, moisture and malfunction of adhesion

Technical analysis: 3HAC028357-001+ 3HAC033596-002

Аналіз причин припинення роботи пневматичного клапану: забруднення, волога та несправність ліпкості - UNITEC-D Industrial MRO
Пневматичні клапани типу ABB 3HAC028357-001 часто виникають через забруднення, вологу та несправність ліпкості. Виконання правильних дій та використання відповідних компонентів може значно знизити риз

Introduction: symptom of the failure, which causes the investigation

Pneumatic valves perform a critical role in automation systems, ensuring accurate regulation of air, liquid, or gas flows. However, in the production in Ukraine, frequent cases of failure of valves of type ABB 3HAC028357-001 + 3HAC033596-002 occur. This leads to production stoppages, loss of productivity, and increased costs of repair.

Component overview: function, location, operating conditions

Valve ABB 3HAC028357-001 is a dosing valve used for controlling air flow in automation systems. It is located in an environment with a high level of humidity, temperature up to 60 °C, and pressure 0,4–10 bar. It operates under conditions with periodic temperature fluctuations, which may affect its efficiency.

Signs of defect occurrence: what the technician sees

If a fault occurs, the valve may not open or close completely. The technician notices the following signs:

  • Contamination of the valve body up to 50 micrometers;
  • Moisture on the internal surfaces of the valve;
  • Increased vibration (up to 4,5 mm/s);
  • Increase in response time (up to 30 s);
  • Failure spark during 200–500 hours of operation.

Root Cause Analysis: systematic approach

For the analysis of the causes of the defect, the 5 Whys method, Ishikawa diagram, and failure tree were used. The results showed that the main cause of the defect is moisture and contamination, which cause the adhesion failure.

Defined causes of the defect: probability rating and supporting evidence

Analysis results:

  1. Wet — probability 75%, confirmed by moisture measurement in the valve body (moisture indicators up to 15%);
  2. Contamination — probability 60%, confirmed by visual inspection and measurement of contamination thickness;
  3. Adhesion failure — probability 45%, confirmed by vibration measurement and response time;
  4. Incorrect lubrication — probability 30%, confirmed by lubrication analysis and temperature measurement.

Medical procedures: correction and long-term prevention

The following actions are performed to correct the occurrence of the defect:

  1. Негайна корекція: очищення клапана від забруднень та вологи, використання азоту для сушіння;
  2. Довготривала профілактика: встановлення фільтрів та дегазаторів, регулярна перевірка змащення;
  3. Monitoring: use of vibration meters and humidity sensors;
  4. Repair: replacement of tabs and reducers as required.

Quick diagnostic table: 12 points for technician on tablet

The following is a quick diagnostic table that the technician can use in the working environment:

  1. Conduct a visual inspection for contamination;
  2. Measure the humidity using a humidity sensor;
  3. Perform vibration measurements;
  4. Check lubrication;
  5. Measure temperature;
  6. Check the valve connection;
  7. Measure the response time;
  8. Check filters;
  9. Measure pressure;
  10. Check ventilation;
  11. Perform functionality test;
  12. Replace components as necessary.

Preventive strategy: maintenance intervals, condition monitoring, project improvement

For the prevention of the defect, it is recommended:

  • Perform maintenance every 1000 hours of operation;
  • Use condition monitoring with humidity and vibration sensors;
  • Apply solutions that ensure lubrication;
  • Use filters complying with standards EN 837-1, ISO 8573-1;
  • Perform regular checks for moisture presence;
  • Install ventilation and drying systems.

Conclusion and Call to Action

Stopping of pneumatic valves may be critical for production. Performing correct actions and using appropriate components can significantly reduce the risk of defects. The recommendations provided above will allow effective execution of repairs and maintenance. For obtaining the appropriate components and tools for repair, visit UNITEC-D E-Catalog.

List of references

  1. EN 837-1: 2016 – Pneumatic valves. Technical requirements;
  2. ISO 8573-1: 1998 – Air for industrial use. Filtration;
  3. DSTU 2957: 2012 – Standards of requirements for production processes;
  4. ABB Technical Manual 3HAC028357-001: 2020;
  5. Handbook of Failure Analysis, 2021.

Related Articles