Preventative maintenance definition

The standard refers to total planned preventive maintenance for which there is no definition in ISO/TS 16949. There is also a requirement for the system to include predictive maintenance. 

The above definition follows the same approach as that used for operating procedures. Equipment and facilities must operate in the safe range. Preventive maintenance helps ensure that equipment stays in that range repair maintenance restores equipment to its normal function. 

One of the most effective safety practices, as well as one highly conducive to productivity, is a definite scheduled program of preventive maintenance. Each item of equipment should be periodically removed from service, carefully inspected and calibrated, any faults or indications of deterioration repaired, and tagged with the date of review and the name of the maintenance person, if more than one technician could have been responsible. A permanent file or maintenance log on each major item of equipment is useful for identifying trends or weak components. 

Involves the systematic replacement of components, according to a predetermined schedule. This means the replacement of components whose life span is known. It also includes systematic lubrication jobs as well as minor upkeep work. This definition avoids confusion between systematic checking or even continual checking to determine the state of the equipment (conditional preventive maintenance) and systematic preventive maintenance. 

For revealed failures the MDT consists of the active mean time to repair (MTTR) PLUS any logistic delays (e.g., travel, site access, spares procurement, administration). For unrevealed failures the MDT is related to the proof-test interval (T), PLUS the active MTTR, PLUS any logistic delays. The way in which failure is defined determines, to some extent, what is included in the down time. If the unavailability of a process is confined to failures while production is in progress then outage due to scheduled preventive maintenance is not included in the definition of failure. However, the definition of dormant failures of redundant units affects the overall unavailability (as calculated by the equations in the next Section). 

Handling these three types of failures under the specified operating conditions of the components is what we call maintenance. Preventive maintenance aims to eliminate potential failures before they occur, e.g. by measuring wear, or by replacement or retraining prior to rapid increases in the failure rate corrective maintenance rectifies failures on occurrence. As components fail and are repaired or replaced, the performance of the system will fluctuate, and at some point in time it is possible that the performance becomes so poor that we say the system has failed. This leads to the definition of system failure rate, X, as the inverse of the mean time between such failures and, given the specified operating conditions. 

The actual (practical) useful life ends when the increased failure rate during wear-out becomes unacceptable in terms of economic or functional considerations. By eliminating the infant mortality failures and replacing them before or soon after the wear-out failures start occurring, the useful life is subject only to the constant failure rate. This is often referred to as preventative maintenance and may fall under the category of Certification Maintenance Requirements (see definitions on page 325). 

A vitamin is defined as an organic compound that is required in the diet in small amounts for the maintenance of normal metabofic integrity. Deficiency causes a specific disease, which is cured or prevented only by restoring the vitamin to the diet (Table 45-1). However, vitamin D, which can be made in the skin after exposure to sunhght, and niacin, which can be formed from the essential amino acid tryptophan, do not stricdy conform to this definition. 

While there are various conceptual approaches to maintenance, the relevant activities may be divided into preventive and corrective maintenance. A considerable part of aU maintenance activity is performed while the plant is shut down however, maintenance may be planned and executed under power operation provided that adequate defence in depth is maintained. For definitions of different types of maintenance, see the Glossary. 

Studies designed (1) to examine the mechanisms underlying the links between diet and disease, and (2) to be the basis for preventive measures for the improvement and maintenance of public health, have an absolute requirement for specific definitions of food components and the availability of reliable methods of measurement. The approach used in the Englyst procedure for the measurement of the constituent sugars of the plant cell-wall NSP provides detailed analytical data that allow for sophisticated hypotheses to be erected and tested. 

Maintenance is totally reactive and does not follow the definition of maintenance, which is to protect, preserve, and prevent from decline (reactive plant culture). 

Lasers are commonly used in the laboratory, although in many instruments, most lasers are embedded in instrumentation and are therefore shielded or protected by optical barriers and interlocks that, when functioning properly, prevent accidental exposure. Care must be exercised when performing maintenance or when changing samples in such instruments. In this section we provide basic information on laser safety and hazards (Refs. 1 to 3). This is by no means exhaustive nor is it meant to substitute for an understanding of the specific safety requirements of instrumentation, or applicable law or regulations. The special case of common laser pointers has received considerable attention recently and is treated separately. We note that as of 2007, the general practice in the United States is to use the lEC definitions. 

Maintenance of equipment under the fire prevention plan. Certain equipment is often installed in workplaces to control heat sonrces or to detect fuel leaks. An example is a temperature limit switch often found on deep-fat food fryers found in restaurants. There may be similar switches for high-temperature diptanks, or flame failure and flashback arrester devices on furnaces and similar heat-producing equipment. If these devices are not properly maintained or if they become inoperative, a definite fire hazard exists. Again, employees and supervisors should be aware of the specific type of control devices on equipment involved with combustible materials in the workplace and should make sure, through periodic inspection or... 

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