What is the length of the 30# door?(and what is it made of?) Many entry or interior doors don't weigh 30#, and they have 2 or 3X 4" hinges, with at least two 2 1/2" screws to catch a stud... Is it hinged vertical or horizontal? If you go with piano hinge, get more sections to go almost full length and beef up the screw depth. But I like to overbuild....
Or is it more like a steamer trunk design? If so, go with three individual hinges
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