Case Study W. K Allah, F. Ballard, A. Al-Dhafiri Saudi Aramco (Hydrocarbon Processing – August 2018)
Pump TypeAPI 610 BB2 – 6 Stages Qty3 ServiceFirst-Pass Reverse-Osmosis FluidRaw Water Flowrate (rated)320 gpm Discharge Pressure650 psig Suction Pressure50 psig Power200 HP
Six-Stages, Back to Back, No balance line, DE (Drive End) Seal Chamber Pressure equivalent to suction pressure. NDE (Non-Drive End) Seal Chamber Pressure equivalent to third –stage discharge pressure.
API PLAN 32 Plan 32 uses a flush stream brought in from an external source to the seal The typical design life for a mechanical seal is 3 yrs.
Pump Non-Drive End Mechanical Seal (NDE) Drive End Mechanical Seal (DE) Flush Stream Source
Fluctuating Pressure in NDE Seal Chamber
Why? Source
Plan 13 Modified (Only for NDE): ◦ Drainage from Seal chamber to Sump, ◦ Flow regulated by valve (3 lpm)
DE: Plan 32 ◦ (Flush Source Pressure > DE Pressure Needed) NDE: Plan ◦ Previously verified TSS < 5 m ◦ Plan 62: Prevent formation of solids from raw water, From Flush Source (180psi) Pressure limited to 3-5 psi with PCV.
What happened during Seal Plan Change? ◦ Noise: Plan 11 Orifice was installed in wrong direction New hole had to be drilled for Plan 62 Drain Connection
Choose the correct Seal Plan, Verify DE and NDE Seal Chamber Pressure Verify Availables Utilities