Maintenance illustrations

Emmons, P. H. Concrete Repair and Maintenance Illustrated Problem Analysis, Repair Strategy, Techniques. Kingston, MA R.S. Means Company, 1994. 

The maintenance of a constant pressure in a system during distillation under diminished pressure is of great practical importance if trustworthy boiling points are desired. Devices which maintain a constant pressure in a system that is higher than the minimum pressure that the pump will give are termed manostats. A simple manostat, due to M. S. Newman, is illustrated in Fig. II, 23, 4. 

Explosion-welded constmction has equivalent or better properties than the more compHcated riveted systems. Peripheral benefits include weight savings and perfect electrical grounding. In addition to lower initial installation costs, the welded system requires tittle or no maintenance and, therefore minimizes life-cycle costs. Applications of stmctural transition joints include aluminum superstmctures that are welded to decks of naval vessels and commercial ships as illustrated in Figure 11. 

Bubble columns in series have been used to establish the same effective mix of plug-flow and back-mixing behavior required for Hquid-phase oxidation of cyclohexane, as obtained with staged reactors in series. WeU-mixed behavior has been established with both Hquid and air recycle. The choice of one bubble column reactor was motivated by the need to minimize sticky by-products that accumulated on the walls (93). Here, high air rate also increased conversion by eliminating reaction water from the reactor, thus illustrating that the choice of a reactor system need not always be based on compromise, and solutions to production and maintenance problems are complementary. Unlike the Hquid in most bubble columns, Hquid in this reactor was intentionally weU mixed. 

Also the cable alley should be easily accessible to make cable connections, and facilitate easy maintenance and regular checks, as illustrated in Figures 13.2 and 13.34. 

The conductor may not have any inspection or maintenance w indows, btit may be provided with surface openings, as illustrated in Figtire 31,15 to dissipate its interior heat into the enclosure for onw ard dissipation by the enclostire s surface to the atmosphere. This facility, how ever, may not be available in smaller circular conductors if they are extruded as one piece (which is possible in smaller sections),... 

Pocket Guide. When a new maintenance form or procedure is introduced, a quick reference pocket guide can promote understanding and accuracy. The key to effectiveness is a deliberate design to provide maximum illustrations or examples in simple language. If it cannot be prepared in-house, outside help should be sought. Professionalism is essential to good communications. 

The incidents described could occur in many different types of plants and are therefore of widespread interest. Some of them illustrate the hazards involved in activities such as preparing equipment for maintenance and modifying plants. Others illustrate the hazards associated with widely used equipment, such as storage tanks and hoses, and with that universal component of all plants and processes people. Other incidents illustrate the need for techniques, such as hazard and operability studies, and protective devices, such as emergency isolation valves. 

Error free operation and maintenance can only occur within an effective management system. At the level of the task itself, this is provided by operating instructions. However, at a more global level, separate tasks have to be organized in a systematic manner, particularly if hazardous operations are involved, and where several individuals need to coordinate to achieve an overall objective. This section illustrates some accidents due to poor organization of work or failure to carry out checks. 

Sections 2.5.1 to 2.5.7 are not an exhaustive list of equipment, process, maintenance, and data processing factors that influence failure rate, but they are an attempt to make the reader aware of the problems. The following example illustrates some of the points made ... 

On normally operating equipment, because the demand is continuous, all failures can be considered as functions of time but for equipment that is operated intermittently, the relative proportion of demand- and time-related failures in combination with the frequency of demands and the type of maintenance and inspection program will have an impact on its total failure rate. This point is best illustrated by an example ... 

To illustrate the possible variation in failure rates under different operating requirements and maintenance programs assume the following ... 

The efficient heat pump reduces energy use by 1,676 kWh per year on average. Is the efficient model heat pump a good investment Suppose the incremental cost of the efficient unit, as compared with the less efficient unit, is 1,000, and electricity cost 10 cents per kWh. With this price of electricity, the efficient heat pump reduces electricity costs by 167.60 per year. Taking a simplified approach for purposes of illustration and assuming that each unit lasts indefinitely and has no repair, maintenance, or replacement costs, and ignoring possible tax effects, the internal rate of return may be calculated as 1,000= 167.60/r, which is 16.76 percent per year. If the household can borrow money at, say, 10 percent per year and earn 16.76 percent, the investment makes economic sense. If we assume a 10 percent discount rate, the present value of the investment is 1,676, which exceeds the initial investment cost. The net present value is 676, which indicates that the investment is feasible. 

Prepare and file the patent application documents. This document is called a specification. The specification must be clear enough so that anyone skilled in the subject matter of the invention could recreate your invention and use it. In the written portion of the specifications the inventor must slate the claims of the invention. These claims must show that the invention is novel and unobvious. Also, where applicable, illustrations must accompany the specification. There are filing fees for patent applications and if the application is successful there are maintenance fees to keep the patent in force. Literature describing patent applications and how they are to be submitted can be obtained from the Commissioner of Patents and Trademarks, Washington, D. C., 20231. This is also the address to submit properly prepared patent applications. 

Figures 4-19 through 4-36 are self-explanatory illustrations of generalized inspection and maintenance recommendations for each of the hoisting tools.

Figure 1.1 Typical organization of a small plant illustrates that plant engineering is one of the essential functions in any plant. Maintenance is normally a subfunction of plant engineering...

Another method used by some plants to acquire data is hand-held transducers. This approach is not recommended if it is possible to use any other method. Hand-held transducers do not provide the accuracy and repeatability required to gain maximum benefit from a predictive maintenance program. If this technique must be used, extreme care should be exercised to ensure that the same location, orientation, and compressive load are used for every measurement. Illustrates a hand-held device. 

Trend data also must be adjusted for maintenance and repair activities. Figure 44.34 illustrates an average trend curve that indicates a sharp rise in vibration levels. It also reflects that, after repair, the levels drop radically. At this point, all baseline and reference values should be reset. If this does not occur, the automatic trending capabilities of the computer-based system do not function properly. 

Specific goals and objectives will vary from plant to plant. However, we will provide an example that will illustrate the process. Before goals and objectives can be developed for your plant, you must determine the existing maintenance costs and other parameters that will establish a reference or baseline dataset. Since most plants do not track the true cost of maintenance, this may be the most difficult part of establishing a predictive maintenance program. 

The cost of protection of steelwork in a mild industrial atmosphere has been compared for a number of protection schemes" and the relevant data are shown in Table 9.2. The difference in aggregate costs illustrates the importance of considering protection on a whole life rather than on an initial cost basis particularly when maintenance involves a labour intensive operation such as painting. 

Expenditure on corrosion prevention is an investment and appropriate accountancy techniques should be used to assess the true cost of any scheme. The main methods used to appraise investment projects are payback, annual rate of return and discounted cash flow (DCF). The last mentioned is the most appropriate technique since it is based on the principle that money has a time value. This means that a given sum of money available now is worth more than an equivalent sum at some future data, the difference in value depending on the rate of interest earned (discount rate) and the time interval. A full description of DCF is beyond the scope of this section, but this method of accounting can make a periodic maintenance scheme more attractive than if the time value of money were not considered. The concept is illustrated in general terms by considering a sum of money P invested at an... 

Figure 19 illustrates key steps of the FI2O2 formation at the nanostructured catalyst surface. An important feature is the imprintment and maintenance of the (11 0) crystal surface through the polymer template because the specific row of metal atoms favours the formation of hydrogen peroxide while minimizing byproducts such as water. 

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