API standards, as established by the American Petroleum Institute, enable drilling professionals the world over to communicate clearly.he American Petroleum Institute:
*maintains more than 500 standards and recommended practices
*represents the oil and gas industry to the public, Congress, state governments, and media.
American Petroleum Institute Standards for PDC Bits and Tricone Bits Tolerances
Bit Size (In.) O.D. Tolerance (In.)
6 3/4" and smaller -0.015 to +0.00 PDC bits -0.0 to +1/32 Tricone Bits
6 25/32" to 9" -0.020 to +0.00 PDC bits -0.0 to +1/32 Tricone Bits
9 1/32" to 13 3/4" -0.030 to +0.00 PDC bits -0.0 to +1/32 Tricone Bits
13 25/32" to 17 1/2" -0.045 to +0.00 PDC bits -0.0 to +1/16 Tricone Bits
17 17/32" and larger -0.063 to +0.00 PDC bits -0.0 to +3/32 Tricone Bits
PDC bits are gauged by either a "go" gauge or a "no go" gauge.
A "no go"gauge is used to ensure a bit is not smaller than allowed and, as the name implies, it should not go or slip down the entire length of the bit. A "go gauge ensures a bit is not larger than allowed and should slip down the entire bit.
Rock Bit Size and API Standard Connection
3 1/2" to 4 1/2" drill bits - 2 3/8" API Reg. pin
4 5/8" to 5 1/2" drill bits - 2 7/8" API Reg. pin
5 5/8" to 6 3/4" drill bits - 3 1/2" API Reg.pin
7 1/2" to 8 3/4" drill bits - 4 1/2" API Reg. pin
9 1/2 " to 13 3/4" drill bits - 6 5/8" API Reg. pin
14 3/4 " to 26" drill bits - 7 5/8" API Reg. pin
