Compressor Frame Extension Failure Analysis

Problem

The client hired KHE  to examine failed components of a two cylinder, two-stage reciprocating compressor in recycle gas service.

Solution

Using the integrated systems approach, KHE conducted an overall system assessment and failure analysis that consisted of a site visit, examination of maintenance records, interview of maintenance personnel, machine and structural calculations, visual observation of the failed machine, and visual inspection of fracture surfaces. Analysis work indicated a maximum cylinder to frame tension of 26,000 lbs. Calculations of the interaction loads established allowables for the normal condition. It was determined that the bolts used would yield under normal circumstances. Data and analysis suggested that the most likely cause of the failure was the presence of incompressible fluids in the system which caused the bolting to stretch. The utilization of an improper washer reduced the factor of safety of the bolted joint in operation.

Results

The client examined the upstream process to eliminate incompressible fluid introduction into the process flow. Maintenance procedures were reviewed and updated. The compressor was repaired and put backinto service with high reliability.