Definition
Regular Connection — A Regular (REG) connection is an API rotary-shouldered connection with a relatively small internal bore and robust cross-section, commonly used on drill collars, bit subs and bits where strength matters more than flow area.
Also known as: regular connection, REG connection, regular thread
What Regular means
The Regular (REG) connection is one of the original API rotary-shouldered connection families. Compared with Full Hole and Internal Flush, the REG connection has a smaller bore and more metal in the connection cross-section, trading flow area for strength and durability. That makes it a natural choice where robustness outweighs hydraulics.
REG connections are identified by size, for example 6-5/8 REG or 7-5/8 REG. They are the standard connection on many drill bits, bit subs and larger drill collars.
Where it fits
- Bit connections — most roller-cone and fixed-cutter bits use an API REG pin.
- Drill collars — larger collars often use REG for its strong section.
- Single shoulder — REG is a single-shouldered API connection.
Renting REG-connection tools
Because bits and subs typically thread with REG connections, matching the collar and sub connections correctly is essential. We rent drill collars and BHA components in the REG sizes your bit and BHA require — contact us to confirm the connection at the bit.