Balanced failure

Balanced failure - simultaneous FRP tensile rupture and concrete crushing... 

The relations between the activities of demand creation and physical supply... illustrate the existence of the two principles of interdependence and balance. Failure to co-ordinate any one of these activities with its group-fellows and also with those in the other group, or undue emphasis or outlay put upon any one of these activities, is certain to upset the equilibrium offerees which means efficient distribution. 

Using the case of f = 3 and p = 0.3 as an example, p, = 0.877 when r = 1 in contrast to, say, 0.886 when r = 0.98. This illustrates that failure to maintain stoichiometric balance continues to have a limiting effect on polymerization in this case also. 

The problem could be maintenance, operation, or design, or a combination of any or all these factors. In all honesty, you should never. see this set of evidence marks because it indicates a lack of control. Now because the mechanic cannot control operational problems or design problems, the first phase to correct this situation is to control the mechanical maintenance factors, like alignment, proper bolting and torque. sequences, be sure shafts are straight and round, and dynamically balance all rotary components. Reinstall the pump and wait for the next failure. Once the maintenance factors are under control, there should appear a clear vision and path to resolve any operational and/or design weaknesses. 

The easiest way to prevent many unplanned premature seal failures is to use balanced o-ring cartridge designed seals. Most of the seal manufacturers make models incorporating these design features. 

Too little maintenance results in unexpected failures and consequential major losses of production and/or customers (Figure 7-1). This impractical approach is termed reactive strategy and should be avoided on all important machinery. Optimum maintenance strategy balances reasonable costs with maximum possible availability and reliability. The two main maintenance strategies employed by companies today are labelled predictive strategy and preventive strategy. These are part of a balanced approach as shown in Figure 7-2. 

As discussed above, adequate backup features must be included to reduce the probability of such a major failure to an acceptably low level and balanced against the consequences, should such a failure occur. The following backup arrangements are normally required as a minimum ... 

It is generally desirable to minimize the diameter of a tubular reactor, because the leak rate in case of a tube failure is proportional to its cross-sectional area. For exothermic reactions, heat transfer will also be more efficient with a smaller tubular reactor. However, these advantages must be balanced against the higher pressure drop due to flow through smaller reactor tubes. 

A failure modes and effects analysis is a systematic analytical technique for identifying potential failures in a design or a process, assessing the probability of occurrence and likely effect, and determining the measures needed to eliminate, contain, or control the effects. Action taken on the basis of an FMEA will improve safety, performance, reliability, maintainability and reduce costs. The outputs are essential to balanced and effective quality plans for both development and production as it will help focus the controls upon those products, processes, and characteristics that are at risk. It is not the intention here to give a full appreciation of the FMEA technique and readers are advised to consult other texts. 

One major oil and chemical company has collected data on the cost of accidents, the equipment involved and the cause of the failure for more than 50 years. These data are analyzed annually to help decide where to focus efforts to reduce losses and/or to modify design standards to prevent recurrence. This analysis also identifies failures of the PSM and ESH management system. These can be compared with the cost of delivering the systems and adjustments made to expenditures to improve the cost/benefit balance. Any such changes must be carefully considered as normal statistical variation may cause you to take unjustified action. 

Sometimes the failure occurs by propagation of a crack that starts at the top and travels downward until the interface is completely debonded. In this case, the fracture mechanics analysis using the energy balance approach has been applied [92] in which P, relates to specimen dimensions, elastic constants of fiber and matrix, initial crack length, and interfacial work of fracture (W,). 

Elimination of potential thrust bearing failure due to failure of the large diameter balance piston labyrinth. 

Belt-drive fault frequencies are the frequencies of the driver, the driven unit, and the belt. In particular, frequencies at 1X the respective shaft speeds indicate faults with the balance, concentricity, and alignment of the sheaves. The belt frequency and its harmonics indicate problems with the belt. Table 44.1 summarizes the symptoms and causes of belt-drive failures, as well as corrective actions. 

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