ABOUT FRICTION FACTOR

THE RIGHT PREMIUM COMPOUND FOR YOUR APPLICATION

The thread compound friction factor helps determine the correct amount of makeup torque required for rotary-shouldered connections. The makeup torque calculations for rotary-shouldered connections in API 7G were based on lead-based thread compounds, which have a friction factor of 1.0. Many thread compounds manufactured currently are not lead-based and do not have friction factors equal to 1.0.

To determine the correct amount of makeup torque required for a connection, multiply the friction factor by the required makeup torque for connection specified in API 7G.

For example, the makeup torque for drill pipe with 5 ½ x 3 ¼ NC50 tool joints is 21,914 ft-lb. If the friction factor is 1.1, the required torque to makeup the connection is:

21,914 x 1.1 = 24,105 ft-lb.

The same calculation applies when the friction factor is less than 1. In the above example, if the compound has a friction factor of .9, the required torque is:

21,914 x .9 = 19,723 ft-lb.