Industrial Park



THE SIGNAL December 2014


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Case Study: Fatigue Crack Growth Assessment Used to Specify New Inspection Interval

A recent inspection of the top head of a processing tower identified cracking at the weld toe of several nozzles. The cracks were identified and sized with phased array ultrasonic inspection. A Known Flaw analysis indicated that the cracks were considered stable at their current size under the worst case loading conditions. However, since the vessel is in cyclic operation, new inspection intervals were required to monitor the growth of the cracks.

Fatigue crack growth calculations in Signal FFS were used to determine the remaining life of the existing cracks. From those results, new inspection guidelines were developed and a new inspection plan was implemented.

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Quiz Question

What options does Signal FFS offer for defining variable amplitude fatigue cycles?

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Quiz Answer:

A tabular histogram and a Raleigh distribution.