Machinery Damage

In many cases, the most frequent cause of equipment outage is the lubrication system. Because magnetic bearings do not wear out, and do eliminate oil, pumps, filters, coolers, and regulating and mixing valves, the potential for improved reliability is obvious. Reliability is also enhanced by the control system, which offers continuous real-time protection. The system automatically shuts down before machinery damage can occur. 

In general, the cost of maintenance increases as the fault detection point advances, as in Fig. 16.1. The least cost occurs when the problem is a fluid fault. Early detection and repair of the source of the fluid fault prevents machinery damage and, if discovered early enough, the in-service oil may also be recovered by filtering or purification. By contrast, if the fluid fault is allowed to progress, the oil becomes... 

Environmental conditions include unguarded or faulty machinery, damaged or faulty tools and equipment, poorly illuminated or ventilated workplaces and untidy, dirty or overcrowded workplaces. 

The costs covered by insurance are those which come within the scope of workers compensation, motor vehicle, properly, machinery damage, fire, public risk, etc. 

An analysis of the data from previous years shows that machinery damage has contributed to over 50% of all accidents. This could be attributed to several factors including poorly maintained equipment, incorrect operation, age, lack of automation, etc. The graph in Figure... 

Nonoxidizing Antimicrobials. Nonoxidizing antimicrobials usually control growths by one of two mechanisms. In one, microbes are inhibited or killed as a result of damage to the ceU membrane. In the other, microbial death results from damage to the biochemical machinery involved in energy production or energy utilization. 

As we said in the introduction, friction absorbs a lot of work in machinery and as well as wasting power, this work is mainly converted to heat at the sliding surfaces, which can damage and even melt the bearing. In order to minimise frictional forces we need to make it as easy as possible for surfaces to slide over one another. The obvious way to try to do this is to contaminate the asperity tips with something that (a) can stand the pressure at the bearing surface and so prevent atom-to-atom contact between asperities (b) can itself shear easily. 

As with any power equipment, gas turbines require a program of planned inspections with repair or replacement of damaged components. A properly designed and conducted inspection and preventive maintenance program can do much to increase the availability of gas turbines and reduce unscheduled maintenance. Inspections and preventive maintenance can be expensive, but not as costly as forced shutdowns. Nearly all manufacturers emphasize and describe preventive maintenance procedures to ensure the reliability of their machinery, and any maintenance program should be based on manufacturer s recommendations. Inspection and preventive maintenance procedures can be tailored to individual equipment application with references such as the manufacturer s instruction book, the operator s manual, and the preventive maintenance checklist. 

Figure 13-23 suggests recommended pulse level (peak-to-peak) pressure pulsations for acceptable pipe vibration. Figure 13-24 presents allowable machinery and pipe vibration at safe limits and damage levels, and Figure 13-25 presents allowable pressure pulsations for various pipe spans between rigid supports when a 5 mil peak-to-peak vibration is allowed at the center of the pipe spans for the pipe sizes noted. 

Figure 13-24. Allowable machinery and pipe vibration at safe iimits and damage ieveis. (Used by permission Everett, W. S. Hydrocarbon Processing and Petroleum Refiner, V. 43, No. 8, p. 117, 1964. Guif Pubiishing Company. Aii rights reserved.)...

Reciprocating compressors deliver a pulsating flow of gas that can damage downstream equipment or machinery. This is sometimes a disadvantage, but pulsation dampers can be used to alleviate the problem. 

Avoidance of damage to plant/machinery/building stmc-tures 42/715... 

Accuracy and reproducibility are of vital importance to industry. Quite apart from the effect of these factors on the final product, several plant items are frequently links in a continuous chain of production processes. A sizing error in one machine, for example, could overstress and damage the succeeding machinery. Similarly, an error in a press may increase stress on the tool and could necessitate an additional operation to remove excessive flash . Wear in a material preparation unit could allow oversize material to be passed to a molding machine, creating an overload situation with consequent damage. 

Periodic alignment checks on all coupled machinery are considered one of the best tools in a preventive maintenance program. Such checks are important because the vibration effects of misalignment can seriously damage a piece of equipment. Misalignment of more than a few thousandths of an inch can cause vibration that significantly reduces equipment life. 

The production of dry steam is important because wet steam may damage equipment and machinery, breaking valves and fittings and causing deposits in superheaters and turbines. 

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