Definition(s)
Bending Strength Ratio
The ratio of the section modulus of a rotary shouldered box at the point in the box where the pin ends when made up divided by the section modulus of the rotary shouldered pin at the last engaged thread.
Source: API RP 7G, Recommended Practice for Drill Stem Design and Operating Limits, Upstream Segment, Sixteenth Edition, August 1998 (Addendum 2: September 2009). Global Standards
Bending-Strength Ratio (BSR)
Ratio of the section modulus of the box thread at its last engaged thread to the pin thread at its last engaged thread.
Source: API RP 7G-2, Recommended Practice for Inspection and Classification of Used Drill Stem Elements, First Edition, August 2009. Global Standards
Bending Strength Ratio (BSR)
Ratio of the section modulus of a rotary shouldered box at the point in the box where the pin ends when made up, to the section modulus of the rotary shouldered pin at the last engaged thread.
Source: API SPEC 7-1, Specification for Rotary Drill Stem Elements, First Edition, March 2006 (Addendum April 2011). Global Standards