Making Size on Size Branch Connections with Repads
PVE-7253, Last Updated: July 29, 2013, By: Cameron Moore and Laurence Brundrett
Modeling size on size connections with repads can be difficult. This method developed by Cameron Moore here at PVEng is particularly useful because it creates a properly contoured repad that can be used for a Drawing or for Finite Element Analysis.
The finished product – a size on size branch connection complete with repad – welds are not shown
The start of the development: two surface parts – 1) the OD of the branch and 2) the OD of the Repad on the Header are developed.
This is what makes this method work so well – the repad outer surface is trimmed to the OD of the branch pipe…
… and extended an equal amount all the way around. Note that the repad is bent under itself as it goes around the branch pipe. A projected cut from the branch onto of the OD of the repad would not work.
Thickening the repad converts it from a surface to a solid. Note that the edges are perpendicular – a feature that cannot be obtained by using projected cuts.
A solid header has been created and the surface branch has been replaced by solid pipe. Here shown in section view.
An opening in the header for the branch completes the model unless repad and header fillet welds are also required…
… addition of the welds.
The solid model made this way is without gaps making for easy FEA analysis!