A natural gas plant in the Middle East had been using a multi-stage, heavy duty vertical turbine pump, type 60-WUJ-2M, in organic lean amine production that was continuously failing.
Lean amine is an organic compound that can absorb hydrogen sulfide and carbon dioxide from sour natural gas.
The temperature of the pump service ranges from 6°C to 59°C. European antimony-impregnated hard carbon bushings had been installed due to its low cost.
However, due to the low viscosity pump system used, it experienced flashing and run dry episodes.
The carbon bearings would also severely score the shaft, which led to major repairs. Graphalloy bearings and bushings are used in many low viscosity pump applications to help eliminate these problems.
Pumping fluids with low lubricity can be especially difficult for metallic bearings.
The hydrodynamic film provided by these low lubricity liquids is unable to provide sufficient lubrication which can lead to metal-on-metal contact. Working with the facility’s design team, Graphite Metallizing Corporation engineers recommended Graphalloy Babbitt-grade bushings to replace the hard carbon material.
Graphalloy is self-lubricating and non-galling and works in a wide temperature range, from -267°C to 537°C.
Graphalloy is a softer material that will not damage the shaft.
These qualities make the bushings a good match for severe service pumps, as it can survive frequent flashing and run dry episodes better than metal or plastic wear parts, while protecting the rotating part from damage.
Graphalloy bushings also allow for tighter clearances and improved pump efficiencies. The upgraded pump went back into service and has been working well for several years now.
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