Case 1 Failed Lined Pipe

A plastic-lined pipe was removed from service due to severe cracking as seen in Fig. 10.35. Severe cracking and corrosion were the two visual features of the liner. Pieces of the plastic liner could be broken off by hand indicating essentially no strength. Why did this failure occur  

An investigation of the failure indicated that the lined pipe transported a process stream containing hydrofluoric acid (HF). Normal practice requires the use of perfluoropol5mier-lined pipe, e g., PTFE or PFA, neither of which are expected to be attacked by HF in the process stream. The rational question to ask is Is the liner actually a perfluoropolymer This question can be answered by performing infrared spectroscopy and differential scanning calorimetry on a sample of the liner. 

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Power lines severed m Controls damaged n Block walls fail Frame collapses Frame deforms Case damaged Frame cracks Piping breaks... 

Power lines severed m Controls damaged n Block walls fail o Frame collapses p Frame deforms q Case damaged r Frame cracks s Piping breaks t Unit overturns or is destroyed u Unit uplifts (0.9 filled) v Unit moves on foundation... 

Figure 2 shows a practical example. In this particular case, it is assumed that the probability failure of a pipe depends on the fluid pressure magnitude. Three probability thresholds are defined on the cumulative distribution function. One simulation is spawned (0). As soon as the pressure of the fluid reaches a value corresponding to a 33% probability (CDF), a stop signal is sent and the framework starts two new simulations (branches). The branch in which the system evolved to the newer condition (pipe failed, red line) carries 33% of the probability, while the other the complementary amount. The same procedure is repeated at point 2. 

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