A multi jackbolt tensioner including a jackbolt body having a plurality of holes with threads to receive jackbolts having torque receiving surfaces all disposed about the periphery of each jackbolts in a mutually non parallel relation to prevent the unauthorized application of torque or stress. The torque receiving surfaces of each bolt head are defined by vertices at the intersect of n number of unsymmetrical arranged torque receiving surfaces of a polygon, where n is an odd integer.