An apparatus includes a body, a shaft assembly, and an end effector. The shaft assembly includes an outer tube, an inner tube, and an acoustic waveguide. The end effector includes an ultrasonic blade and a clamp arm. The ultrasonic blade is acoustically coupled with the acoustic waveguide. A first portion of the clamp arm is pivotably coupled with a distal end of the outer tube. A second portion of the clamp arm is pivotably coupled with a distal end of the inner tube. The outer tube and the inner tube are configured to removably couple with the body such that the outer tube, the inner tube, and the clamp arm are configured to removably couple with the body and the remainder of the shaft assembly and end effector as a unit.
