Page 245 - Failure Analysis Case Studies II
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Fig. 6 Fracture surface away from the outer edges
W * " I
Fig. 7. Close-up view of the highlighted area in Fig. 6
4. CONCLUSIONS AND RECOMMENDATIONS
The microscopic examination showed that the impulse line failed through high-cycle fatigue. This
is confirmed by FE analysis in that peak vibration (in the tubing) occur at low frequencies, with
maximum stress points localised at the failure point. The root cause of failure is excessive vibration
emanating from the connecting flange at the discharge pipe. It is believed that a significant amount
of this vibration is induced by the dynamics of the flow within the discharge manifold. Without
decoupling this motion, it is probable that similar failure will occur in the future. The following
measures were recommended:
