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How Failure Analysis Can Enhance Workplace Safety by Revealing Hazards

April 12, 2022

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Failure Analysis Enhances Workplace Safety

Companies with the means and protocols in place for identifying the reason behind a component failure can better maintain a safe and efficient work environment. By doing so, failure analysis can help protect against reoccurring costly equipment failures once the failure has been determined and corrected, while overall increasing peace of mind among personnel.

Constellation PowerLabs offers comprehensive failure analysis services which apply a full-scale suite of inspections, tests and imaging technologies to detect, pinpoint and correct component configurations which are experiencing substandard integrity or have failed.

In a recent failure analysis and testing case, Constellation PowerLabs’ personnel employed an array of tests and analyses to determine the exact failure point in an overheating power cable.

Hazard Prevention Finds a Culprit

Initially, an aluminum- and steel-stranded power conductor cable was taken out of service due to elevated heat signature. The client’s facility-wide thermal imaging safety protocols detected a faulty component during a routine inspection which was brought to Constellation PowerLabs for comprehensive analysis. This was done so that the hardware could be analyzed, the fault located, and the problem prevented in similar pieces of equipment. The last phase of the output line, which six months prior had registered a 58 degrees Celsius level, had recently been measured emitting a thermal signature of 88 degrees Celsius. As the 30-degree increase presented a potential hazard, company managers elected to help determine the root cause of the failing cable.

Constellation PowerLabs Initiates an Investigation

When the failed cable was examined, it was noted that the cut end allowed a cross-section view of the 72 individual aluminum strands across a diameter of 1.766 inches. Meanwhile, the terminated end of the cable was welded into a four-bolt, heavy-duty industrial connector. Signs of usage were present such as dirt on the underside of the connector plate and discoloration at clamp sites along the length of the cable. Yet, no external indications of failure were visible to the naked eye.

Enhanced Imaging Shows No Failure in the Line

Next, the engineer ran a corona imaging test in order to search for an exact site of conductivity failure along the length of the cable. The cable was suspended from an isolated line and then butted against a high-voltage (100 kV) generator at the unterminated end. The 100kV created a corona ionization to be emitted and detected at the termination end by a special UV corona imaging camera. This was later suppressed by attaching a Tesla toroid to the termination end, allowing any severed strands along the length of the cable that were emitting ions to be detected. None were detected, so this eliminated the possibility of a failure somewhere along the 16-foot length of the cable, suggesting a probability that the failure site was at the termination end of the cable.

Failure Analysis Turns Up the Heat

The next phase of the investigation from PowerLabs’ failure analysis services began with black electrical tape being applied to the circumference of the cable every 12 inches for measuring purposes. Then, both ends of the cable were attached to a high-current generator, creating a complete circuit. Once the cable was warmed up, the engineer passed 1,500 amps of current through the cable and infrared (IR) measurements were taken every 10 minutes. IR images and temperature measurements taken over a period of 80 minutes revealed relatively lower temperatures along the length of the cable, reaching a maximum of just 150 degrees Fahrenheit. The cut end emitted temperatures exceeding 400 degrees Fahrenheit while the termination end had a maximum heat signature of 240 degrees Fahrenheit. This further confirmed the integrity of the cable along its entire 16-foot length, prompting further investigation into the termination coupling.

Dissection Reveals Failure

A bandsaw cut was made 16 inches from the cable termination. A pull test resulted in 22 of the 27 strands in the outer layer coming away easily, warranting further dissection. A second cut was made into the connector at 0.09” from the termination. Here, a pull test revealed that only 13 of the 72 aluminum strands and three of the seven steel strands were actually attached to the weld. The final determination was then made that the strands failed at the end of the weld point from gradual fatigue over time rather than from mechanical overload.

Conclusion: Valuable Data for Hazard Prevention

This level of investigation exemplifies the comprehensive approach taken by Constellation PowerLabs failure analysis services to help determine root cause of equipment failures. This data can be applied to company safety standards to prevent future malfunctions, to increase productivity and to enhance workplace safety.

In addition to investigating failures due to gradual fatigue, failure analysis is also used to detect, analyze, and prevent hazards caused by structural buckling, kinetic impact, mechanical overload, failure creep (due to prolonged loading) and erosive and corrosive wear.

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