There’s nothing nominal about discussions of diameter. Make sure it’s clear in project specifications whether you’re talking inside our outside diameter. Source: iStock
A borehole has a single diameter, but a drill string (rotary/reverse drill pipe, hollow stem augers, drive casing and sonic drill pipe) has two: inside diameter and outside diameter, affectionately referred to as ID and OD. Add well screen and casing to the mix and you potentially have five diameters to deal with when installing a well (borehole, drill string ID and OD, well casing ID and OD). Oh, and you may need temporary tremie pipe, and/or a permanent sounding tube. (I have even seen specifications calling for a separate “camera tube.”) It can get confusing. You get the idea. We’ve probably all been there.