API5CT nominal linear weight and PE linear weight

[toque73]

I am relatively new to OCTG and am attempting to follow the tables in the API5CT. I must admit that I cannot follow the WT calculations between the correlation between the nominal linear weight and the PE linear weight. How can I convert the nominal to PE to get the WT? Another point is how you calculate the WT for dimensions not listed there, e.g. 6" 27.38lb/ft P110? I would appreciate it if you could explain to me how you can get the WT for this dimension. Thanks!