During the construction phase of a project, one of the contractors decided to install heavier repads for some of the Tee’s and even decided to replace some of these fittings with tees of a heavier schedule.
While he assumes full responsibility for the changes, by stamping the documents, I’m trying to asses what other aspects (consequences) he may overlook with the “upgrade”.
This is what I could see as potential issues:
- using heavier schedule fittings with lighter schedule pipe may increase hydraulic losses beyond what the process group factored in for their calculations;
- overall flexibility of the piping systems will decrease resulting in increasing the equipment loadings beyond acceptable limits;
- SIF’s will change, rendering the local stress evaluation done in CAESAR as erroneous;
- in fact, by modifying the wall thickness at these intersections, the contractor renders the entire analysis done in CAESAR as inaccurate for all the lines subjected to these changes.
His motivation for the modifications lies in the fact that FEA run on the original configuration resulted in failed members (tees).
I have no means of checking that but I know that the materials engineer on the project has used the code to determine wall thickness requirements for pipe and fittings, including tees, elbows, etc.
Please comment.