Pneumatic Pressure Testing Incident – Valve Overpressure Event
Background
Our inspection team supervised a pneumatic pressure test on a valve with a target pressure of 7 bar. Present at the site were our lead inspector, the manufacturer’s quality control representative, a technician, and a third-party inspector (TPI). All personnel were positioned close to the valve, under the assumption that 7 bar was a relatively low pressure and posed minimal risk.
Incident Overview
Pressure was gradually increased using a partially used gas cylinder. The primary pressure gauge showed a rise to 4 bar, then stopped. Assuming the cylinder was empty, it was replaced with a new one; however, the gauge still read 4 bar. The team concluded that pressure was not building.
Suspecting a gauge issue, the valve was cautiously opened to verify. At that moment, a secondary gauge located on the opposite side suddenly registered a pressure spike exceeding 40 bar. The original gauge had malfunctioned; its needle was stuck at 4 bar, giving a dangerously false reading. The actual pressure had far exceeded safe limits, resulting in permanent damage to the gauge.
Fortunately, no injuries occurred; however, the event highlighted a serious lapse in pressure monitoring protocol that could have led to catastrophic consequences.
Root Cause Analysis
1. Instrument failure:
The primary gauge was defective; its needle was stuck, providing inaccurate readings.
2. Single-point monitoring:
The team relied solely on one gauge without cross-verification.
Key Learnings
1. Redundancy is critical:
Always use at least two calibrated gauges during pressure testing to cross-check readings.
2. Treat all pressure testing as high-risk
Even low-pressure tests can escalate into hazardous situations.
3. Maintain a safe distance:
Personnel should remain at a safe distance and use remote monitoring wherever feasible.
4. Pre-test instrument checks
All gauges and instruments must be verified for calibration and functionality before testing begins.
This case study reflects PTC Inspect’s commitment to safety, precision, and continuous improvement in industrial inspection services. Our team brings deep expertise to every project, helping clients across oil & gas, marine and heavy industries mitigate risk and ensure operational integrity.
