Insert Plate Geometry 1

[jehan17718]

One typical use of insert plates (i.e. locally thickened shell/ head) is used when nozzle loads are very high. In regard to this, I have the following two questions.

1. How should the diameter of a circular insert plate be finalised? Is there a thumb rule to fix the diameter? Please elaborate on how to fix the same based on a WRC 107/ PD5500 Annex G output?

2. If an insert plate is used for a nozzle which is very close to the tangent line can the insert plate edge have a rectangular shape at the edge at which it will be welded to the dished head?

Thanks in advance.

-jehan

 

[gr2vessels]

jehan,
The thickening of the shell plate (or adding reo plate) serves the distribution of stresses over a larger area / aka larger volume of material. The approximate limit of useful stress distribution has been established at the diameter of two finished openings. Beyond that limit the contribution of additional material is not significant. The taper of the thicker plate edge down to the shell thickness serves the distribution of concentrated stresses due to sudden chenge of section geometry. I apologise for this trivial reply, I hope it helps. I also assume that the above helps in setting the input data for PV Elite design you are using.
The dished end should be selected with a length of skirt, to avoid welding on/near the tan line. If the dished end does not have skirt, then the insert plate should look like a letter "D" and welding the flat side to the head tan line. The square ends of the insert plate will intersect the circ weld of the head at 90 deg, thus minimizing the local stresses (I believe that the question 2 was pointing to the same shape of the insert).
Cheers,
gr2vessels