Support failures

The possibility of pipe support failure resulting from ej osure to low temperatures (which may embrittle the supports) or high temperatures (which may weaken them). 

Excursions outside these process limits may produce a yield crash or, worse, a longer-term reliability problem. The well-characterized process is less prone to such problems and when they do occur the capability is at hand to support failure analysis. 

The prepared membranes SILMs showed high CO2 permeability (744 barrer) and CO2/He selectivity of 8.6. Furthermore, the stabihty of the membranes at higher temperature (125 °C) approached the range of interest in the capture of CO2 from coal gasification plants. However, higher temperatures could not be reached mainly due to the support failure rather than any effect on the ionic liquid. 

Temperature stability is important for some applications of SILMs in gas separation, such as capture of CO from coal gasification plants. Ilcovich et al. [25] analysed the stability of a SILM based on [hmim+lfNTfj ] supported on a polysulphone organic membranes in the selective separation of CO from He at high temperature. This membrane was found to be stable up to 125 C, the failure of the membranes above that temperature being attributable to support failure rather than any effect on the ionic liquid. Recently, Myers et al. [32] reported operation of [hmim ][NTfj ] supported on nylon membranes up to 300 C. It was found that permeability in this [hmim [NTfj ] membrane increased with temperature while the selectivity decreased. 

Trays and downcomers should be firmly bolted to their supports. Failure to do so may result in excessive deflection, flow restriction, leakage, and deficient mechanical integrity. 

Finally, with regard to condition based maintenance (CBM) of engineering systems it is important to detect the initiation of incipient faults, to assess the current health of a system and to predict the remaining useful life (RUL) of a component that has become faulty. As bond graph modelling enables the systematic generation of ARRs for FDI, it can also support failure prognosis. 

We conclude therefore that unless cryogenic pipelines are properly designed for the condition of bowing as well as uniform thermal cool-down, intolerable pipe displacements, severe pipe stresses, and pipe support failures will undoubtedly occur. 

Deterioration. Paintings are composite objects that have high vulnerabiUty. The various materials are adhered to each other, especially in a laminated stmcture, to form a source of potential trouble. Any dimensional change in one of the components or between the components as a consequence of changes in environmental conditions results in a strain on the adhesion of the various parts. Strains can lead to failure of the adhesion. This is one of the principal causes of losses in panel paintings, where the dimensional changes in the wooden support cause losses in adhesion between the paint layer and the support. 

The steel shell that encloses the refractory is exposed to significant forces from the expansion of the refractory as well as the load from the refractory and the charge within the furnace. Similarly, the stmctures that support the furnace and the foundations must be designed to assure safe operation. A failure of any component can have serious consequences. 

Artificial Hearts. Congestive heart failure (CHF) is a common cause of disabiHty and death. It is estimated that three to four million Americans suffer from this condition. Medical therapy in the form of inotropic agents, diuretics (qv), and vasofilators is commonly used to treat this disorder (see Cardiovascularagents). Cardiac transplantation has become the treatment of choice for medically intractable CHF. Although the results of heart transplantation are impressive, the number of patients who might benefit far exceeds the number of potential donors. Long-term circulatory support systems may become an alternative to transplantation (5). 

Stress Corrosion Crocking. Stress corrosion cracking occurs from the combined action of corrosion and stress. The corrosion may be initiated by improper chemical cleaning, high dissolved oxygen levels, pH excursions in the boiler water, the presence of free hydroxide, and high levels of chlorides. Stresses are either residual in the metal or caused by thermal excursions. Rapid startup or shutdown can cause or further aggravate stresses. Tube failures occur near stressed areas such as welds, supports, or cold worked areas. 

Figure 15.19 Examples of crack patterns due to stress-corrosion cracking and corrosion fatigue in branch connections and vessel or pipe support attachment welds. (Reprinted with permission from Helmut Thielsch, Defects and Failures in Pressure Vessels and Piping, New York, Van Nostrand Reinhold, 1965.)...

The section illustrated in Figs. 15.24 and 15.25 was removed from the door frame that supports the side-loading door to the furnace (Fig. 15.26). Failures of this type had been a chronic problem in the door frame area. The section had been fabricated by welding together three steel plates of to % in. (1.3 to 1.9 cm) thickness. 

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