Improving compressor maintenance

In the past, we have discussed various aspects of compressor maintenance. It is now time to offer an overview of compressor maintenance. As in many human endeavors, the quality of our activities should take precedence over quantity. In compressor maintenance, as in maintenance of any other type of machinery, the quality focus must be accomplished through predictive or preventive maintenance.

Quality operations demand uptime and functioning of compression equipment. To achieve these requirements, it has long been recognized that maintenance activities designed to anticipate and avoid failure have been, and continue to be, a sound investment in the overall maintenance strategy. Many companies are investing in software programs to improve maintenance strategy. Yet, no computer system can help a maintenance department, if the bas­ic elements of a preventive and predictive maintenance program are not in place.

Both small and large facilities have identifiable components of a preventive and predictive maintenance pro­gram that can be generally described by seven elements:

• Facilities management 
• Inspection routines 
• Predictive and diagnostic activities 
• Integration of maintenance within the production activity 
• Insurance activity 
• Corrective activity 
• Continuous improvement.

Some of these elements are discussed below.

Facilities management. Each significant piece of equipment and its component hierarchy is uniquely and logically identified, so that all maintenance activity can be related and an equipment history maintained. Once each piece of equipment has been identified, equipment maintenance procedures manuals should be compiled. Consultation of these documents, together with the maintainer’s own equipment knowledge, will assist in developing quality preventive and predictive maintenance.

Inspection routines. Establishing effective routines and meaningful frequencies requires thorough study of the compressor operating environment, the manufacturer’s documentation, consultation with manufacturer’s representatives, and careful study of past experience. Once this has been accomplished, established routines and frequencies must be subjected to ongoing refinement and adjustment. It is important that routines ensure specificity, and where possible, numerical measurements should be utilized. For example, changing product quality, gas composition, pressure ratio, temperature, vibration and noise, are all relevant indicators for the analysis of equipment health. This approach, coupled with visual checks by experienced personnel, will contribute towards a quality program. A philosophy of specificity will help to control excessive frequencies which contribute to significant un­necessary costs. A systematic approach to preventive maintenance activities will help to de­crease preventive maintenance costs, which can be as much as 30% of the overall maintenance labor cost.

Predictive and diagnostic activity. Significant results have been achieved through quantifiable preventive maintenance. Recognition of these results has created a demand for technologies to meet preventive maintenance needs. A quality pro­gram should include one or more of the following diagnostic techniques: 

• Vibration analyses 
• Thermographic techniques 
• Oil analyses 
• Aerodynamic and compression path performance monitoring and trending.

If these techniques are not in use, a re-evaluation of progress in the preventive or predictive maintenance activity may be in order.

Corrective activity. Are your reliability professionals working on fully quantifiable cost-benefit projects? An excellent base for prioritizing the maintenance engineering activity, for example, are history records containing information on the facilities management activity, quantifiable cost data from preventive maintenance, and other maintenance activities. Sound, corrective designs – while requiring significant investment – can achieve enormous cost benefits in parts and labor.