Alfred Conhagen, Inc is a major US pump and steam turbine design and repair specialist. For years, the company struggled with the design of unique pump components trying to strike a balance between performance and manufacturability.
The company was particularly concerned about entrained solids and thermal growth of close clearance components in eight-stage and six-stage high performance centrifugal pumps designed for high temperature refinery service – operating at 450OF/230OC. At this temperature both octane and diesel have poor lubricity. There was pipe scale and some coke fines in the diesel application and the octane pump had occasional catalyst carryover which was destroying fine clearances.
Together with Alfred Conhagen’s engineers, we designed a solution which involved coating the hydrodynamic/hydrostatic radial and thrust bearings in the centrifugal pump. The chosen substrate was 410 stainless steel to match the thermal coefficient of the other parts in the assembly and maintain close clearance over a wide temperature range. The bearings have been in service for eleven years during which time they have experienced moderate to severe ingestion yet the coated bearing surfaces remain in excellent condition with no reduction in performance or change of vibration signature.
The Hardide process allows Alfred Conhagen to machine finish the intricate geometry before a precise thickness of the Hardide coating is added to produce a part with high wear resistance and a low coefficient of friction.