Interpreting "e" value & arc length per UG-80 & UG-29 resply

Dear Friends,

I am trying to find out the "e" value as specified in UG-80 using Fig. UG-80.1.
Further I am trying to find out the arc length for template using Fig. UG-29.2.
My parameters for graph is as mentioned below;

L/Do = 10.59
Do/t = 57

As the above mentioned L/Do is beyond the graph limit of Fig. UG-80.1. Further also point of intersection of L/Do & Do/t is beyond the limit of Fig. UG-29.2, please guide me to calculate the "e" value and Template arc length for the above mentioned parameters.

Best Regards,
Gaurav Kankariya

Hello Gaurav,

When a vessel shell is rolled from a plate into a cylinder, it might not be perfectly round. The 'e' value is the maximum diameter minus the minimum diameter divided by the average diameter - basically.

The graph in Figure UG-80.1 is only a representation of the value 'e'. UG-80(b)(2) discussed the value of 'e' when consideration is given to external pressure. A careful reading of that paragraph states what to do when values fall off the graph.