This is difficult to answer without a few sketches, but ...

The pressure is applied at first closure, the thrust load (PA) is then resoled at the closest, stiffest boundary condituion to that closure. Hopefully, a few examples will illustrate this.

• Assume leaving the nozzle, you have a straight run of pipe to an elbow, with no intermediate restraints. The PA load acting on the elbow will be resolved at the nozzle. Therefore, pressure thrust load should be included in the nozzle evaluation.
• Assume leaving the nozzle, you have a straight run of pipe to a pump. The PA load will primarily be resolved at the pump anchorage. Therefore, pressure thrust load should not be included in the nozzle evaluation.
• Assume leaving the nozzle, you have a straight run of pipe to an elbow, with an intermediate axial restraint. The PA load will be resolved at the axial restaint. Therefore, pressure thrust load should not be included in the nozzle evaluation.
• Assume leaving the nozzle, you have a straight run of pipe to an elbow, with an intermediate untied expansion joint. The expansion joint is too flexible to transmit load, so the PA load will be resolved at restraints on the far side of the elbow. Therefore, pressure thrust load should not be included in the nozzle evaluation. <em>If the expansion joint was tied, you would include the pressure thrust.</em>
• Assume leaving the nozzle, you have a straight run of pipe to an elbow, followed by additional runs, elbows, and restraints. This is a <em>maybe</em> situation. It depends on how far the restraint is from the first elbow.

I hope this helps.

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Regards,
Richard Ay (COADE, Inc.)


[This message has been edited by rich_ay (edited May 04, 2001).]