Engineering Insights: Increase Component Lifetime with Proactive Management of Spare Parts in LNG Tankers

In the realm of LNG tanker operations, managing spare parts, particularly high-pressure packings, is a critical task demanding foresight and precision. The high-pressure packing, designed specifically for Laby-GI in the LNG marine sector, is the case described here. Not typically listed as a spare part, this component necessitates intricate replacement procedures, often beyond the scope of regular crew skills, requiring specialized service technicians.

The necessity for early wear detection cannot be overstated. These packings, subject to wear, need replacement every 16,000 to 20,000 operating hours. However, the process is not only time-intensive but also fraught with potential installation errors, further underscoring the need for expert intervention.

Recent observations from LNG tankers reveal a concerning pattern, detectable only through advanced monitoring systems. When these packings near their service life limit, prompt replacement is essential. Yet, operational constraints often preclude timely technician deployment, leading to risky 'make-do' solutions.

The real issue surfaces when wear-induced abrasion from the packing material, typically plastic, mixes with oil and reacts with high temperatures to form a sticky substance. This substance then accumulates in the final pressure valve, requiring significantly higher back pressure to function — up to 400 bar, compared to the normal 300 bar. This change, unfortunately, doesn't affect standard control parameters, making it imperceptible to operators.

The repercussions of such overpressure are severe. The stress on both the valve and the worn packing is exacerbated, especially given that the machinery is designed for a maximum of 350 bar. This situation creates a detrimental cycle of increasing wear and pressure.

To mitigate these risks, an innovative approach was adopted. A swift, focused intervention, based on machine diagnostics, involved replacing the final pressure valve within a 60–120-minute shutdown. This procedure not only resolved the immediate issue but also alleviated pressure on the packing, effectively breaking the wear-pressure cycle.

While this solution addresses the symptom rather than the root cause, it buys crucial time for planned maintenance, significantly increasing the likelihood of achieving it without premature machine downtime or financial loss.

The screenshot from the PROGNOST®-NT monitoring system and images of replaced components, vividly illustrate these challenges and solutions, offering valuable insights into effective spare parts management in LNG tankers.