Jake,
Thank you for the update..
unfortunately, i just started a new project and it happened to me again:( ..
I noticed that the mainline sch. 40 is always there in the default pipe data, however i never used or added it to my default pipes.
and I am not able to delete it permanently.
I kept clearing it then saving then it comes again when I check the pipe data.
Kindly see the attached file..
Nibal