Liquid Ring Vacuum Pump

Liquid Ring Vacuum Pump

Graham PV82000 Liquid Ring Vacuum Pump

This liquid ring vacuum pump is used in a critical application on an off-shore Oil and Gas Platform in Hibernia, Newfoundland.

Problem:

The Graham PV82000 liquid ring vacuum pump had severe wear due to cavitation and washout; severe damage and out-of-spec repairs due to a prior catastrophic failure.

Solution:

The non-drive-end bearing had failed on a previous occasion, so that the shaft was supported by a clearance hole in a sideplate.

Extensive measurement was carried out using a precision CMM arm, allowing original part fit and offset relationships to be determined. 3D CAD models were built of the entire assembly, with final part sizes, fits, running clearances, and offsets determined in the context of the assembly. In cases where the wear or damage was too severe to determine original dimensions, industry standard values were used and checked in comparison to other parts of that family in our 22,000 part database.

Severely worn parts were repaired by weld build up and machining, or where necessary damaged areas were removed by machining and replaced with machined inserts, which were welded in place, then finish-machined as a single part, where possible.

Where necessary due to the condition of parts, fatigue life, or in response to customers’ requests, parts were replaced. For example, the shaft was replaced with a different alloy to match the electronegativity of the housing material and to assist with the observed corrosion problem.

Final assembly was carried out by a dedicated project team consisting of engineers, millwrights, and machinists, to control a set of exceptionally critical .004” tolerances on 4 running clearances over 2 pump stages in a 14-dimension tolerance stack-up.