A petrochemical plant operated multiple reciprocating pumps to handle high-pressure fluid transfer. These pumps relied on packing sets to seal the plunger and prevent leakage. Packing wear was a recurring issue, leading to leaks, reduced efficiency, and costly downtime.
The plant’s maintenance strategy was based on fixed time intervals for packing replacement. This approach often resulted in:
Premature replacement, increasing maintenance costs.
Unexpected failures, causing environmental and safety risks.
The team needed a predictive method to determine the optimal time for packing replacement.
The plant implemented stroke count monitoring as a key performance indicator. Each stroke represented a plunger cycle, and packing wear correlated strongly with cumulative stroke count.
Data Analysis
Historical records showed packing typically lasted 1.2–1.5 million strokes before leakage began.
Manufacturer guidelines were compared with actual field data.
Blue curve: Estimated % of packing life consumed versus cumulative strokes (sigmoid-shaped to reflect slow initial wear, followed by accelerated end-of-life wear).
Dashed red line (1.1M strokes): Example replacement trigger tied to stroke count.
Orange band (1.0–1.2M strokes): Inspection window where leak checks and gland adjustments are planned to avoid unplanned outages.
Instrumentation
Installed stroke counters on each reciprocating pump.
Integrated counters with the plant’s assets in Tenan.
Threshold Setting
Established a predictive maintenance trigger at 1.1 million strokes (≈90% of average life).
Configured alerts for operators when pumps approached this threshold.
Maintenance Planning
Scheduled packing replacement during planned outages.
Reduced emergency interventions by aligning replacements with production schedules.
Unplanned Downtime: Reduced by 70%.
Maintenance Cost Savings: 25% reduction due to optimized packing usage.
Safety & Compliance: Eliminated leakage-related incidents.
Reliability: Pump performance stabilized, improving throughput.
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