Skip to main content

Maintenance Strategies Options


A maintenance strategy or option means a scheme for maintenance, i.e. an elaborate and systematic plan of maintenance action. Following are the maintenance strategies that are commonly applied in the plants.

• Breakdown Maintenance or Operate to Failure or Unplanned Maintenance
• Preventive or Scheduled Maintenance
• Predictive or Condition Based Maintenance
• Opportunity Maintenance
• Design out Maintenance

The equipment under breakdown maintenance is allowed to run until it breaks down and then repairing it and putting back to operation. This strategy is suitable for equipments that are not critical and have spare capacity or redundancy available. In preventive or scheduled Maintenance, maintenance actions such as inspection, lubrication, cleaning, adjustment and replacement are undertaken at fixed intervals of numbers of hours or Kilometers.
An effective PM program does help in avoidance of accidents. Condition monitoring (CM) detects and diagnoses faults and it helps in planned maintenance based on equipment condition. This condition based maintenance strategy or predictive maintenance is preferred for critical systems and for such systems breakdown maintenance is to be avoided. A number of CM techniques such as vibration, temperature, oil analysis, etc. have been developed, which guide the users in planned maintenance.
In opportunity maintenance, timing of maintenance is determined by the procedure adopted for some other item in the same unit or plant. In design out maintenance, the aim is to minimize the effect of failures and in fact eliminates the cause of maintenance. Although it is an engineering design problem, yet it is often a responsibility of maintenance department. This is opted for items of high maintenance cost that are due to poor maintenance, poor design or poor design outside design specifications. It may be mentioned that a best maintenance strategy for each item should be selected by considering its maintenance characteristics, cost and safety.

In addition to the above, new strategies concepts such as Proactive Maintenance, Reliability Centred Maintenance (RCM), Total Productive Maintenance (TPM), etc. have recently been evolved to look it from different perspectives and this has helped in developing effective maintenance. In proactive maintenance, the aim is identify what can go wrong, i.e. by monitoring of parameters that can cause failures. In RCM, the type of maintenance is chosen with reliability of the system in consideration, i.e. system functions, failures relating to those functions and effects of the dominant functional system failures. This strategy in the beginning was applied to critical systems such as aircrafts, nuclear and space applications. At present, this is being extended to critical systems in the plant.
TPM, a Japanese concept, involves total participation of all concerned. The aim is to have overall effectiveness of the equipment with participation of all concerned using productive maintenance system.

Comments

Popular posts from this blog

Maintenance 4.0 Implementation Handbook (pdf)

WHAT IS MAINTENANCE 4.0? Industry 4.0 is a name given to the current trend of automation and data exchange in industrial technologies. It includes the Industrial Internet of things (IIoT), wireless sensors, cloud computing, artificial intelligence (AI) and machine learning. Industry 4.0 is commonly referred to as the fourth industrial revolution. Maintenance 4.0 is a machine-assisted digital version of all the things we have been doing for the past forty years as humans to ensure our assets deliver value for our organization. Maintenance 4.0 includes a holistic view of sources of data, ways to connect, ways to collect, ways to analyze and recommended actions to take in order to ensure asset function (reliability) and value (asset management) are digitally assisted. For example, traditional Maintenance 1.0 includes sending highly-trained specialists to collect machinery vibration analysis readings on pumps, motors and gearboxes. Maintenance 4.0 includes a wireless vibration sensor conne

27 steps of the Gearbox Repair and rebuilding

 27 steps of the Gearbox Repair and rebuilding: Step 1 Cleaning exterior of Gearbox and identification. Step 2 Remove all bolts from the gearbox. Step 3 Disassembly for Gearbox preliminary evaluation of the condition and repair required Step 4 Mag inspect Gearbox. Step 5 check all Gears. Step 6 Customer communication of health of the Gearbox. Step 7 Parts to be repaired or, reverse engineered parts where needed required for Gearbox rebuild. Step 8 Failure analysis during complete disassembly and evaluation of the component wear and damage. Step 9 Cleaning all internal components and housing. Step 10 Check all bearings diameters in house. Step 11 Check all shafts Step 12 inspect all Gears. Step 13 Set up check line bore of the gearbox. Step 14 Repair and rebuild Gears back to O.E.M Step 15 Replacing all bearings seals and gaskets Step 16 Repair and rebuild all shafts again to O.E.M Step 17 Realigning all gears shafts and bearings back to O.E.M Step

Thermal growth: how to identify, quantify and deal with its effects on turbomachinery

Thermal growth, as used in the field of machinery alignment, is machine frame expansion resulting from heat generation. The generation of heat, of course, is caused by operational processes and forces. Materials subjected to temperature changes from heat generation will expand by precise amounts defined by their material properties. In turbomachinery, thermal growth results from the temperature differences occurring between the at-rest and running conditions. Generally speaking, the greater the temperature difference, the greater the thermal growth. The magnitude of the growth can be calculated from three variables: ∆ T (temperature difference) C   (coefficient of thermal expansion) L    (distance between shaft centerline and machine supports) When machinery begins to generate heat, the temperature difference between at-rest and running conditions will cause thermal expansion of the machine frame, thereby bringing about the movement of the shaft centerlines. This can produce changes in

John Crane's Type 28 Dry Gas Seals: How Does It Work?

How Does It Work? Highest Pressure Non-Contacting, Dry-Running Gas Seal Type 28 compressor dry-running gas seals have been the industry standard since the early 1980s for gas-handling turbomachinery. Supported by John Crane's patented design features, these seals are non-contacting in operation. During dynamic operation, the mating ring/seat and primary ring/face maintain a sealing gap of approximately 0.0002 in./5 microns, thereby eliminating wear. These seals eliminate seal oil contamination and reduce maintenance costs and downtime. John Crane's highly engineered Type 28 series gas seals incorporate patented spiral-groove technology, which provides the most efficient method for lifting and maintaining separation of seal faces during dynamic operation. Grooves on one side of the seal face direct gas inward toward a non-grooved portion of the face. The gas flowing across the face generates a pressure that maintains a minute gap between the faces, optimizing flui

Technical questions with answers on gas turbines

By NTS. What is a gas turbine? A gas turbine is an engine that converts the energy from a flow of gas into mechanical energy. How does a gas turbine work? Gas turbines work on the Brayton cycle, which involves compressing air, mixing it with fuel, and igniting the mixture to create a high-temperature, high-pressure gas. This gas expands through a turbine, which generates mechanical energy that can be used to power a variety of machines and equipment. What are the different types of gas turbines? There are three main types of gas turbines: aeroderivative , industrial, and heavy-duty. Aeroderivative gas turbines are used in aviation and small-scale power generation. Industrial gas turbines are used in power generation and other industrial applications. Heavy-duty gas turbines are typically used in large power plants. What are the main components of a gas turbine? The main components of a gas turbine include the compressor, combustion chamb