(20 min.) Case Study: Cryogenic Submersible Vertical Pump experiencing High Vibration

Ahmad Fadzli Ismail, Staff Engineer, Malaysia LNG Sdn. Bhd.


Three units of cryogenic submersible vertical pump for new LNG tank project underwent Factory Acceptance Test (FAT) at Original Equipment Manufacturer (OEM) shop test bench. Each of this pump equipped with four accelerometers installed at upper and lower bearing. These three pumps could not meet the vibration limit as per project specification. Two dominant peaks were at running frequency and vane pass frequency. These pumps later were dismantled for inspection and further checks. Re-balancing were done at rotor assembly, impeller and balanced drum which the only component not underwent component balancing prior assembly. Computed Flow Dynamic (CFD) analysis were also done to verify series of combination between impeller and diffuser vanes. The presentation will covers vibration plots, diagnostic done to determine the faults and action taken including improvement done to permanently resolve the high vibration issue.
1. Learning about Cyrogenic Submersible Vertical Pump a manufacturer standard pump
2. Challenges in getting the right vibration plot and conduct the diagnostic
3. Checks and engineering review to resolve the high vibration issue


Ahmad has 12 years experience in LNG plant maintenance of rotating equipment. Spent almost 3 years in project as Lead Rotating Equipment Engineer building world first on-shore Boil Off Gas Reliquefaction plant. Certified as Mobius Vibration Analyst Cat III and Machinery Lubrication Analyst (MLA II). Involvement in reliability study, major maintenance activities, condition monitoring, troubleshooting and root cause failure analysis of GE Frame Heavy Duty Gas Turbine, Siemens SGT-700 gas turbine, Mitsubishi steam turbines, Siemens-Dresser Rand centrifugal compressor, Nouvo Pignone Centrifugal and axial compressor, Instrument Air oil free screw and integral gear centrifugal compressor, API 610 pumps and Cryogenic submersible centrifugal pump. Heavily participate in organization capability development by conducting training and coaching session to junior and senior engineers.