Besides the unbalanced thrust load during start up, also look carefully for the stresses in the elbows. Reason being, the high velocity impingement can/will cause erosion corrosion at the elbow, thus resulting in higher stresses in the thinned elbow.I have seen some cases of severe damage of elbow during such high velocity operations.Analysis of the system should not show high stresses in the elbow.

A. Bhattacharya

Stress Analyst

Bechtel Corporation