Maintenance techniques inspection

A comprehensive program that includes predictive maintenance techniques to monitor and analyze critical machines, equipment, and systems in a typical plant. Techniques include vibration analysis, ultrasonics, thermography, tribology, process monitoring, visual inspection, and other non-destructive analysis methods. 

Regular visual inspection of the machinery and systems in a plant is a necessary part of any predictive maintenance program. In many cases, visual inspection will detect potential problems that will be missed using the other predictive maintenance techniques. 

B6 Instrument/equipment, inspection and maintenance B8 Inspection/acceptance of supplies and consumables 2.10 Preparedness and coordination 3.3 Sample preservation techniques 3.9 Field measurements... 

Some records must be retained for specified periods by law. In any case, records should be reviewed periodically to identify repetitive failures which might suggest the need for revised maintenance or design, or more frequent inspections and tests. Conversely, continuously satisfactory results might justify increasing the interval between inspections and tests, subject to statutory requirements. Reliability-based maintenance techniques are valuable tools in this area. 

Kennedy, J. L. 1993. Oil and Gas Pipeline Fundamentals, 2nd ed. Houston Gulf Publishing. Provides basic information on types of pipelines, design, construction practices, welding techniques and equipment, operations, maintenance, repair, inspection, and safety. 

It is essential therefore to make safety assessments/cases, even of the most complex systems, comprehensible to aU concerned and not just to the analyst. They must assist the designer and the operator in making decisions. They must make clear what the critical features are and on what special manufacturing techniques, inspection, crew drills and maintenance procedures they are critically dependent. The purpose of the analysis is not only to convince airworthiness authorities that a system is safe, but also to state clearly those aspects on which safety depends. Safety cases/assessments could therefore be especially useful to operators it they can be used in anger, instead of lying in a dust-gathering tomb. 

When estimating the operating and maintenance costs for various options, it is recommended that the actual activities which are anticipated are specified and costed. This will run into the detail of frequency and duration of maintenance activities such as inspection, overhaul, painting. This technique allows a much more realistic estimate of opex to be made, rather than relying on the traditional method of estimating opex based on a percentage of capex. The benefits of this activity based costing are further discussed in Section 13.0 and 14.0. 

Up-to-day reliability requirements as applied to NPP strength maintenance govern development of new generation of computerized systems for in-service inspection. These systems in parallel with capabilities of ordinary ultrasonic techniques allow to reconstruct high resolution image of inner flaw and increase available amount of information. 

Examples will cover maintenance inspection such as corrosion detection in piping and tanks, but also routine weld inspection. The need for acceptance criteria for weld defects adapted for modern NDT techniques will be highlighted, because these form (in many cases) the key to benefit. 

These techniques include (1) vibration monitoring (2) thermography, (3) tribology, (4) process parameters, (5) visual inspection and (5) other nondestructive testing techniques. This chapter will provide a description of each of the techniques that should be included in a full capabilities predictive maintenance program for typical plants. 

All equipment and systems in the plant should be visually inspected on a regular basis. The additional information provided by visual inspection will augment the predictive maintenance program regardless of the primary techniques used. 

While preventive maintenance is concerned with regularly testing, and reconditioning equipment to prevent failures in service and premature deterioration, it follows that predictive maintenance procedures are concerned with the ability to predict when the equipment will fail and then developing schedules to implement timely repairs. Predictive maintenance does not imply that with the use of these techniques, failure modes in equipment can be prevented rather, it suggests that the occurrence of failure can be predicted and thus planned for. An appropriate example would be the inspection and change of a major compressor face-type oil seal where random heat checking (FM) has been observed over the years. 

T/F approved and enforced (you really meant it) (The focus of this category is the actual maintenance tools, techniques, and standards for work that go beyond the traditional scope of normal inspection and preventive maintenance activities.)... 

In this latter connection both contractors and owner management play a joint role in ensuring reliability of operation and avoidance of unscheduled shutdowns. Great strides have been made in this area with better design, inspection and safety procedures, and by the use of improved maintenance and operating techniques. 

A principal advantage of predictive maintenance is the capability it offers the user to perform inspections while the equipment is operating. In particular, in order to reflect routine operating conditions, the technique requires that measurements be taken when the equipment is notmeilly loaded in its production environment. Since the machine does not need to be removed from the pi uction cycle, there is no shutdown penalty. The ability to conduct machine inspections while equipment is running is especially important in continuous operations such as in utilities, chemical, and petrochemical manufacturing. 

Such a task description invites task analysis, which would lead naturally to human reliability analysis (HRA). Indeed, perhaps the earliest work in this field applied HRA techniques to construct fault trees for aircraft structural inspection (Lock and Strutt 1985). The HRA tradition lists task steps, such as expanded versions of the generic functions above, lists possible errors for each step, then compiles performance shaping factors for each error. Such an approach was tried early in the FAA s human factors initiative (Drury et al. 1990) but was ultimately seen as difficult to use because of the sheer number of possible errors and PSFs. It is occasionally revised, such as in the current FRANCIE project (Haney 1999), using a much expanded framework that incorporates inspection as one of a number of possible maintenance tasks. Other attempts have been made to apply some of the richer human error models (e.g.. Reason 1990 Hollnagel 1997 Rouse 1985) to inspection activities (La-toreUa and Drury 1992 Prabhu and Drury 1992 Latorella and Prabhu 2000) to inspection tasks. These have given a broader understanding of the possible errors but have not helped better define the PoD curve needed to ensure continuing airworthiness of the civil air fleet. 

To minimize the current required to sever the fuse link, a small starter wire of only six strands is provided and wrapped tightly around the mechanical load carrying strands of the fuse link. Upon actuation, a small amount of current is sufficient to start the exothermic reaction in the starter wire, which then carries over to the main link. Continuity in the starter wire is checked on-line by trickle current. Samples of manufacturer s batches of fusible links are tested prior to installation. Statistical sampling techniques will be used. Also, the fusible links will be test actuated when the control rod assembly is removed for periodic inspection and maintenance. 

On-line monitoring, inspection and maintenance development of innovative techniques for monitoring of corrosion conditions and material damage and of improved ultrasonic inspection techniques ... 

In the framework of Markov models, one has shown in (Do Van et al. 2008c) that perturbation analysis and one of its extension presented in (Cao and Chen 1997) can be very well adapted to reliability or maintenance problems at steady state. The second objective of the present paper is to show how the perturbation technique can he used in order to estimate the DIM of Markov models at steady state by using only a single sample path. Moreover, when perturbation parameters have heen estimated, the DIM of any direction can be easily obtained without additional calculations. As a consequence, difierent maintenance policies or inspection schedules can be easily tested and optimized. 

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