Climate-Adapted Lean Six Sigma for Maintenance Improvement in Petrochemical Operations: A Longitudinal Case Study of Cooling-Water Pumps

Maintenance rules in Gulf process plants often come from manufacturer documents written for milder climates. This explanatory case study asks why such a rule persists and what a Lean Six Sigma Define–Measure–Analyse–Improve–Control (DMAIC) project needs to catch it. The case covers 36 months for four American Petroleum Institute (API) 610 cooling-water pumps at a Saudi petrochemical plant, using 47 failure events, 312 work orders, bearing temperature logs and 15 interviews. The dominant failure mode, bearing distress, traced to a quarterly re-lubrication rule fixed in 2015 and applied with a mineral-oil grease. Adopting the bearing makers’ criterion that grease life halves for every 15 °C above 70 °C, an operating-envelope audit showed each summer interval aged the grease two to three times faster than at 70 °C, and eight of eleven baseline bearing events fell in June to September (p = 0.009). After the grade, quantity and interval basis were changed, bearing events fell more than other modes, bearing sets issued fell from nine to three, and summer corrective labour fell from 31 to 9 h. The new 2000 h interval is not supported at peak temperature, so a summer limit is added. The single-site design cannot estimate effect size.