Patent ID: 11440168

Abstract:
A reaction torque limiting backup wrench arrangement (1) has at least one fastener engaging means e.g. spanner (6) or socket (170), for a pressure boundary bolted joint nut (5) of a respective fastener (3). The backup wrench arrangement provides a reaction torque up to a threshold above which rotation allowed by motion of the fastener engaging means is determined by a magnitude of the reaction torque and force deflection characteristic of a biasing arrangement acting directly or indirectly on the fastener engaging means. Tension in the flexible tension element e.g. chain (7) urges the spanner (6) onto the nut (5) of the fastener permitting the spanner to displace when torque transmitted through a bolt to the nut or bolt head within the spanner exceeds a threshold torque, enabling the nut or bolt head to rotate, helping prevent bolt over-tightening, and helping indicate the bolt seizing or galling.